Biology subjects

Miyata, M.

Publications and source records attributed to Miyata, M..

At least 19 recordsLinked to original sources

bioRxiv2026

The rise and fall of feminizing Wolbachia in a butterfly

In sexually reproducing animals, sex ratios generally evolve toward parity1 but can be distorted by selfish genetic elements, including sex chromosome-linked meiotic drivers and cytoplasmically inherited symbionts such as Wolbachia2. We previously documented the rapid spread of the feminizing Wolbachia strain wFem in an island population of the butterfly Eurema hecabe3. Within just four years, the proportion of females increased from approximately 50% in 2015-2018 to 93.1% in 2022. Here, continued monitoring of the same population revealed an equally striking reversal: the sex ratio returned to near parity in 2024-2025, accompanied by a sharp decline in the frequency of wFem. These observations suggest that host-symbiont conflict can drive major shifts in population sex ratio over remarkably short timescales.

evolutionary biology↗

bioRxiv2026

Reconstitution in a minimal synthetic bacterium reveals distinct Mollicute MreB-based motility systems driven by orthogonal force directions

MreB, a bacterial actin homolog, is widely conserved in bacteria where it functions as a scaffold for a peptidoglycan synthesis. Intriguingly, members of the cell wall-lacking Mollicutes retain multiple mreB genes despite the absence of peptidoglycan. Previous work demonstrated that two MreB isoforms from Spiroplasma can reconstitute swimming motility in the minimal synthetic bacterium syn3B, indicating that MreB was repurposed for motility. Here, we expressed seven MreBs from Haloplasma contractile, an early-diverging Mollicute, in syn3B. Approximately 50% of cells elongated, and 15% exhibited curving and coiling movements that resembled Haloplasma but differed from Spiroplasma motility. Systematic analysis of isoform combinations revealed that movement requires specific MreB pairs, and that additional isoforms enhance motility efficiency. Cryo-electron tomography showed membrane-associated ribbons composed of MreB filaments. Mathematical modeling demonstrated that Haloplasma- and Spiroplasma-type movements can be reproduced by altering only the direction of force generation. Thus, diversification of force orientation within an actin homolog enabled independent evolution of distinct motility systems in Mollicutes.

Synthetic Biology↗

bioRxiv2026

Coordinated Membrane Deformation Driven by a Minimal Set of Spiroplasma MreB Isoforms

Spiroplasma are wall-less helical bacteria that swim by switching the handedness of their helices. In most bacteria, MreB, a bacterial actin, forms relatively static filaments beneath the membrane to organize cell wall synthesis. In contrast, Spiroplasma eriocheiris encodes five MreB isoforms (SpeMreBs), and swimming requires a pair of isoforms, SpeMreB5 together with SpeMreB4 (or the related isoform SpeMreB1) (1) Yet how these MreBs generate force and membrane deformation remains unclear. To examine the membrane-deforming activities of SpeMreBs, we demonstrated a simple reconstitution system using the non-motile synthetic bacterium JCVI-syn3B and purified SpeMreBs expressed in Escherichia coli. Lysates of syn3B expressing SpeMreB5 deformed liposomes in a concentration-dependent manner. In contrast, lysates co-expressing both SpeMreB5 and SpeMreB4 showed a plateau in the frequency of deformation, suggesting that SpeMreB4 suppresses membrane deformation driven by SpeMreB5. Deformed liposomes exhibited either fluctuating or stable behaviors. ATP depletion changed both the frequency and behavior of deformation, indicating that membrane remodeling depends on the nucleotide state of SpeMreBs. Reconstitution with purified SpeMreBs from E. coli confirmed that SpeMreB5 alone deforms membranes, whereas SpeMreB1, a member of the same class as SpeMreB4, suppresses deformation. These results suggest that membrane shape in Spiroplasma is dynamically regulated by antagonistic interactions among isoforms of SpeMreBs isoforms and their nucleotide-dependent assembly states.

synthetic biology↗

bioRxiv2025

Astrocytic Cathepsin D truncates α-synuclein and promotes Lewy neurite-like aggregation in neurons

Parkinsons disease (PD) and related synucleinopathies are marked by the accumulation and propagation of -synuclein (-syn) aggregates, a process primarily studied in neurons. However, the contribution of astrocytes to this process remains unclear. Here, using a physiologically relevant neuron-astrocyte co-culture system that recapitulates tripartite synapse architecture, we show that astrocytes actively process and propagate -syn aggregates. Astrocytes internalize -syn pre-formed fibrils (PFFs) and cleave them into C-terminally truncated, seeding-competent species via the lysosomal protease Cathepsin D (CtsD). These truncated species are subsequently transferred to neurons, where they promote the growth of Lewy neurite (LN)-like aggregates. Notably, -syn PFF exposure disrupts lysosomal membrane integrity in astrocytes, leading to CtsD upregulation. These findings reveal a feed-forward mechanism in which astrocytic lysosomal dysfunction amplifies -syn pathogenicity. Our findings identify astrocytes as active contributors to -syn propagation and highlight the astrocytic lysosomal pathway as a potential therapeutic target in PD.

pathology↗

bioRxiv2025

Live imaging of bacterial actin MreBs causing helicity switching of a minimal synthetic cell

Spiroplasma swim by switching their helical body into right- and left-handed. Helicity formation and switching can be reconstituted in an immotile minimal synthetic bacterium, JCVI-syn3B by introducing the pair of bacterial actin, MreB4 and MreB5. Here, we analyzed MreB behaviors optically, to investigate this unknown mechanism. We tried MreB4 fluorescence labeling by protein fusion. The labeling was not achieved, because the fusion of fluorescent protein or peptide to 16 positions resulted in immotile constructs. These results may suggest that MreB4 has many interaction interfaces with other proteins. Induced expression of MreB4 to cells with constitutive MreB5 expression resulted in earlier and higher frequency of motile cells, distinct from the results of constitutive MreB4 and inducible MreB5. Next, the behavior of labeled MreB5 was analyzed. Photobleaching and photoactivation suggested static behavior of MreB5 during cell movements. Cell treatment by A22, a MreB polymerization inhibitor caused helix deformation, movement stall, and diffusion of MreB5 fluorescence, suggesting that A22 sensitive MreB5 interaction should be involved in helix formation and motility. SignificanceSpiroplasma MreB is a unique bacterial actin that causes motility with a different mechanism from other actins. Here, we investigated the helicity switching involved in the motility. Fluorescently traced MreB behaviors suggested that the motility mechanism is not coupled with its replacement in the internal structure.

biophysics↗

bioRxiv2025

Eukaryotes' closest relatives are internally simple syntrophic archaea

Eukaryotes are theorized to have originated from an archaeal phylum Promethearchaeota (formerly Asgard archaea)1,2. The first cultured representatives revealed valuable insight3,4 but are distantly related to the first eukaryotic common ancestor (FECA), leaving many unknowns regarding this archaeons biology. Here, we report isolation of two strains belonging to the order proposed as FECAs closest relative, Hodarchaeales,5 as members of a pure co- and tri-culture with methanogenic partners. Both are obligately anaerobic, syntrophic, peptide-degrading, and mesophilic archaea that have simple internal cell structure and produce protrusions and vesicles, like Promethearchaeales3,4. All strains demonstrate behavior focused on cell construction rather than division, unlike typical prokaryotes6. Strain HC1 possesses genes associated with aerobic lifestyles but lacks complete pathways for aerobic respiration and co-cultures cannot grow under (micro)aerobic conditions, suggesting the genes support oxygen detoxification rather than respiration. Reflecting this, HC1 can survive and grow under microaerobic conditions only when aerobic organisms are present. Phylogenetic analyses indicate FECA may have possessed these genes and thus some aerotolerance. Physiological, genomic, and phylogenetic observations indicate FECA was a simple-celled anaerobic syntrophic peptide-degrading archaeon with a non-growth-centric lifestyle and potential adaptations towards an oxygenated planet--the archaea-eukaryote transition was steep in both cell structure and aerobiosis.

microbiology↗

bioRxiv2025

Visualization of peptidoglycan layer isolated from gliding diderm bacteria, Flavobacterium johnsoniae and Myxococcus xanthus, by quick-freeze deep-etch replica electron microscopy

The bacterial peptidoglycan layer plays an important role in protecting the bacteria from turgor pressure, viruses, and predators. However, it also acts as a barrier in transmitting forces generated on the cell membrane to adhesion proteins on the surface during gliding locomotion. In this study, peptidoglycan layers were isolated from two species of gliding diderm, i.e., Gram-negative bacteria, and their structures were visualized by quick-freeze deep-etch replica electron microscopy. The diameter of pores in the peptidoglycan layer of M. xanthus and the area of surface pores were 51 nm and 14.6%, respectively, which were significantly larger than those of E. coli (32 nm and 5.8%) and F. johnsoniae (29 nm and 7.0%). Based on this, we discussed the mechanism by which diderm bacteria transmit forces across the PG layer to the bacterial surface. SignificancePeptidoglycan is a rigid meshwork that protects bacterial cells from turgor stress, virus, and predators. Bacteria move to get nutrients and escape from predators. The force for motility is generated in the cell membrane and transmitted to the surface across the peptidoglycan layer. In this study, the peptidoglycan structures of two representative gliding Gram-negative bacteria were visualized to understand the transmission mechanism.

microbiology↗

bioRxiv2024

FtsZ of wall-less bacteria forms ring-like structures

The FtsZ protein is involved in bacterial cell division. In cell-walled bacteria, such as Bacillus subtilis, FtsZ forms a ring-like structure, called the Z ring, at the cell division site and acts as a scaffold for cell wall synthesis. The inhibition of cell wall synthesis in B. subtilis has been shown to interfere with the function of the Z ring, causing a loss in cell division control. Spiroplasma, a cell wall-less bacterium, lacks most of the genes involved in cell division; however, the ftsZ gene remains conserved. The function of Spiroplasma eriocheiris FtsZ (SeFtsZ) remains to be determined. In the present study, we analyzed the biochemical characteristics of SeFtsZ. Purified SeFtsZ demonstrated lower polymerization capacity and GTPase activity than FtsZ from E. coli and B. subtilis. We also investigated the relationship between SeFtsZ and SeSepF, which anchors FtsZ to the cell membrane, and found that SeSepF did not contribute to the stability of FtsZ filaments, unlike the B. subtilis SepF. SeFtsZ and SeSepF were produced in E. coli L-forms, where cell wall synthesis was inhibited. SeFtsZ formed ring-like structures in cell wall-less E. coli cells, suggesting that SeFtsZ forms Z rings and is involved in cell division independently of cell wall synthesis.

microbiology↗

bioRxiv2024

A highly active bacterial actin actuates the polymerization of another isoform essential for swimming motility of Spiroplasma

Spiroplasma is a wall-less helical bacterium that is characterized by a unique swimming motility involving five isoforms of the bacterial actin MreBs (SMreB1-5). The functions of SMreBs are unique in the MreB family proteins, as their counterparts in walled-bacteria are involved in maintaining the cell shape by scaffolding the cell-wall synthesis complex through their static properties. In vitro analyses of individual SMreBs provide clues to understand the detailed molecular mechanism of Spiroplasma swimming. However, the purification difficulties have hampered in vitro analyses of one of the SMreBs, SMreB1, which drives the swimming. Here, we isolated soluble SMreB1 of Spiroplasma eriocheiris (SpeMreB1) and evaluated its activity. SpeMreB1 was expressed as a fusion with a solubilization-tag, ProteinS (PrS), which allowed us to purify it in the soluble fraction. SpeMreB1 exhibited the highest phosphate release rate and the fold changes of critical concentrations for polymerization across the nucleotide states among the MreB family proteins. SpeMreB1 interacted with polymerized SpeMreB5, another SMreB essential for Spiroplasma swimming. In the AMPPNP- or ADP-bound state, SpeMreB1 decreased the amount of SpeMreB5 filaments, possibly reflecting their disassembly. Regardless of the nucleotide state, SpeMreB1 bound to negatively charged lipids. These results suggest that SpeMreB1 utilizes its highest activity to manage SpeMreB5 filaments underneath the cell membrane to drive Spiroplasma swimming. ImportanceIn most bacterial species, MreB is involved in cell-shape maintenance by localizing the bacterial cell-wall synthesis complex with its static properties. In contrast, five isoforms of MreBs in a pathogenic wall-less helical bacterium Spiroplasma are involved in its unique motility system driven by a kink propagation along the helical cell. Our integrated biochemical assays show that one isoform of MreBs involved in the swimming of a crustacean pathogen S. eriocheiris (SpeMreB1) is exceptionally active in the MreB family proteins and manages the polymerization of another MreB essential for the swimming (SpeMreB5). This study sheds light on an evolutionary mystery how Spiroplasma has adapted static MreB proteins to a dynamic phenomenon like its swimming motility.

biophysics↗

bioRxiv2024

Establishment of a rapid method to assemble and transfer DNA fragments into the JCVI-syn3B minimal synthetic bacterial genome

JCVI-syn3B (syn3B), a minimal synthetic bacterium that only possesses essential genes, facilitates the examination of heterogeneous gene functions in minimal life. Conventionally, Escherichia coli is used to construct DNA fragments for gene transfer into the syn3B genome through Cre/loxP system. However, the construction process is challenging and time-consuming due to various issues, including the inhibition of E. coli growth and unexpected recombination, especially with AT-rich DNA sequences such as those found in Mycoplasma genes. Therefore, in this study, we aimed to develop a new transformation method to overcome these issues. We assembled the vector and target DNA fragments using an in vitro homologous recombination system and subsequently transferred the products into the syn3B genome. We obtained approximately 103[~]104 recombinant colonies per milliliter of the original culture in eight days, which is four days shorter than the conventional period, without any recombination issues, even for AT-rich DNA. This method may be applicable to other gene manipulation systems based on Cre/loxP system. SignificanceA rapid and trouble free method was developed to transfer genes to the genome of minimal synthetic bacterium JCVI-Syn3B through Cre/loxP system. This method can be applied to Cre/loxP-based gene manipulation system in various research fields.

synthetic biology↗

bioRxiv2024

Dimeric assembly of F1-like ATPase for Mycoplasma gliding motility

Rotary ATPases, including F1Fo- and V/A-ATPases, are molecular motors that exhibit rotational movements for energy conversion1. In the gliding bacterium, Mycoplasma mobile, a dimeric F1-like ATPase forms a chain structure with the glycolytic enzyme, phosphoglycerate kinase (PGK), within the cell2, which is proposed to drive the bacterial gliding motility2-4. However, the mechanisms of force generation and transmission remain unclear. Here, we present a 3.2 [A] resolution structure of the dimeric ATPase complex obtained using electron cryomicroscopy (cryo-EM). Notably, the structure revealed an assembly distinct from that of known dimeric forms of F1Fo-ATPase5, despite containing conserved F1-ATPase structures. The two ATPase units were interconnected by GliD dimers, previously identified as MMOB16202,6. Gli{beta}, a homologue of the F1-ATPase catalytic subunit6, exhibited a specific N-terminal region that incorporates PGK into the complex. Structural conformations of the catalytic subunits, catalytically important residues, and nucleotide-binding pattern of the catalytic sites of the ATPase displayed strong similarities to F1-ATPase, suggesting a rotation based on the rotary catalytic mechanism conserved in rotary ATPases1,7-10. Overall, the cryo-EM structure underscores an evolutionary connection in the rotary ATPases and provides insights into the mechanism through which F1-like ATPase drives bacterial gliding motility.

microbiology↗

bioRxiv2024

Visualization of Bacillus subtilis Spore Structure and Germination using Quick-Freeze Deep-Etch Electron Microscopy

Bacterial spores, known for their complex and resilient structures, have been the focus of visualization using various methodologies. In this study, we applied quick-freeze and replica electron microscopy techniques, allowing observation of Bacillus subtilis spores in high-contrast and three-dimensional detail. This method facilitated visualization of the spore structure with enhanced resolution and provided new insights into the spores and their germination processes. We identified and described five distinct structures: (i) hair-like structures on the spore surface, (ii) spike formation on the surface of lysozyme-treated spores, (iii) the fractured appearance of the outer spore cortex during germination, (iv) potential connections between small vesicles and the core membrane, and (v) the evolving surface structure of nascent vegetative cells during germination.

microbiology↗

bioRxiv2024

Rapid spread of a vertically transmitted symbiont induces drastic shifts in butterfly sex ratio

BRIEF SUMMARYSex ratio dynamics constitutes a pivotal subject in evolutionary biology1. Under conditions of evolutionary equilibrium, the male-to-female ratio tends to be approximately 1:1; however, this equilibrium is susceptible to distortion by selfish genetic elements exemplified by driving sex chromosomes and cytoplasmic elements2,3. While previous studies have substantiated instances of these genetic elements distorting the sex ratio, studies specifically tracking the process with which these distorters spread within populations, leading to a transition from balanced parity to a skewed, female-biased state, are notably lacking. Herein, we present compelling substantiation regarding the rapid spread of the cytoplasmic endosymbiont Wolbachia within a localized population of the pierid butterfly Eurema hecabe (Figure 1A). This resulted in a shift in the sex ratio from near parity to an exceedingly skewed state overwhelmingly biased toward females, reaching 94.4% within a remarkably brief period of 4 years.

evolutionary biology↗

bioRxiv2024

Cell-based assays and comparative genomics revealed the conserved and hidden effects of Wolbachia on insect sex determination

It is advantageous for maternally transmitted endosymbionts to skew the sex ratio of their hosts toward females. Some endosymbiotic bacteria such as Wolbachia cause their insect hosts to exclusively produce female offspring through male killing or feminization. In some lepidopteran insects, male killing is achieved by affecting the sex-determining process in males, and a unique mechanism of male killing and its functional link with feminization have been implicated. However, comparative analysis of these phenotypes is often difficult because they have been analyzed in different host-symbiont systems and transinfection of Wolbachia across different hosts is often challenging. In this study, we demonstrated the effects of nine Wolbachia strains on the splicing of sex-determining genes in Lepidoptera by fixing the host genetic background using a cell culture system. Cell transinfection assays confirmed that three male killing-inducing Wolbachia strains and one feminization-inducing Wolbachia strain increased the female-type splicing products of the core sex-determining genes doublesex, masculinizer, and zinc finger protein 2. Regarding Wolbachia strains that do not induce male killing/feminization, three had no effect on these sex-determining genes, whereas two strains induced female-type splicing of masculinizer and doublesex but not zinc finger protein 2. Comparative genomics confirmed that homologs of oscar, the Wolbachia gene responsible for male killing in Ostrinia, were encoded by male killing/feminizing Wolbachia strains, but not by non-male killing/non-feminizing strains. These results demonstrated the conserved effects underlying male killing and feminization induced by oscar-bearing Wolbachia, and suggested other potential mechanisms that Wolbachia might employ to manipulate host sex. IMPORTANCEArthropods commonly carry maternally transmitted microbial symbionts such as Wolbachia. The lack of paternal transmission frequently led to the evolution of reproductive parasitism traits, namely the manipulation of host reproduction in favor of female hosts, substantiated by male killing and feminization. Although Wolbachia induces these phenotypes in a wide range of insects, the underlying mechanisms, diversity, and commonality remain largely unclear. In this study, we used a combination of transinfection assays and comparative genomics to reveal the conserved effects of male killing and feminizing Wolbachia strains on lepidopteran sex determination. Furthermore, we demonstrated that some non-male killing/non-feminizing Wolbachia strains also have an inherent ability to influence sex determination, albeit in a different manner, suggesting the potential for multiple mechanisms to manipulate host sex. This study also implied the frequent evolution of host suppressors against Wolbachia-induced reproductive manipulation.

microbiology↗

bioRxiv2024

Internal structure of Mycoplasma mobile gliding machinery analyzed by negative staining electron tomography

Mycoplasma mobile is a parasitic bacterium that forms gliding machinery on the cell pole and glides on a solid surface in the direction of the cell pole. The gliding machinery consists of both internal and surface structures. The internal structure is divided into a bell at the front and chain structure extending from the bell. In this study, the internal structures prepared under several conditions were analyzed using negative-staining electron microscopy and electron tomography. The chains were constructed by linked motors containing two complexes similar to ATP synthase. A cylindrical spacer with a maximum diameter of 6 nm and a height of 13 nm, and anonymous linkers with a diameter of 0.9-8.3 nm and length of 5-30 nm were found between motors. The bell is bowl-shaped and features a honeycomb surface with a periodicity of 8.4 nm. The chains of the motor are connected to the rim of the bell through a wedge-shaped structure. These structures may play roles in the assembly and cooperation of gliding machinery units. SignificanceMycoplasma mobile, a parasitic bacterium, glides on solid surfaces at speeds of up to 4.0 m per second through a specialized mechanism. The gliding machinery, located at one pole of the cell, is composed of surface legs and internal motor structures. The force generation unit within the internal structure evolved from ATP synthase. This study aimed to clarify the entire architecture of the gliding machinery using electron tomography.

microbiology↗

bioRxiv2023

Role of the medial agranular cortex in unilateral spatial neglect

Unilateral spatial neglect (USN) results from impaired attentional networks and can affect various sensory modalities, such as visual and somatosensory. The rodent medial agranular cortex (AGm), located in the medial part of the forebrain from rostral to caudal direction, is considered a region associated with spatial attention. The AGm selectively receives multisensory input with the rostral AGm receiving somatosensory input and caudal part receiving visual input. Our previous study showed slower recovery from neglect with anterior AGm lesion using the somatosensory neglect assessment. Conversely, the functional differences in spatial attention across the entire AGm locations (anterior, intermediate, and posterior parts) are unknown. Here, we investigated the relationship between the severity of neglect and various locations across the entire AGm in a mouse stroke model using a newly developed program-based analysis method that does not require human intervention. Among the various lesion positions, acute severity was higher with the lesion in the intermediate rostrocaudal position. On the other hand, the recovery from USN-like behavior after this phase tended to be slower in cases with more rostral lesions in the AGm. Additionally, no motor paralysis was observed in any of the mice with lesions in each AGm. These results suggest that the intermediate rostrocaudal position of the AGm may significantly influence selection of the direction, regardless of the areas to which it is connected. On the contrary, recovery from USN-like behavior may be dependent on the areas to which it is connected. HighlightsLesion of the rodent medial agranular cortex (AGm) results in unilateral spatial neglect (USN). In the acute phase, the severity was higher with lesions in the intermediate AGm position. Recovery from somatosensory USN tended to be slower with rostral AGm lesions. Recovery from USN may depend on sensory modalities associated with the connected areas. Our results revealed location-dependent differences in attentional functions within the AGm.

animal behavior and cognition↗

bioRxiv2023

Cell surface architecture of the cultivated DPANN archaeon Nanobdella aerobiophila

The DPANN archaeal clade includes obligately ectosymbiotic species. Their cell surfaces potentially play an important role in the symbiotic interaction between the ectosymbionts and their hosts. However, little is known about the mechanism of the ectosymbiosis. Here, we show cell surface structures of the cultivated DPANN archaeon Nanobdella aerobiophila strain MJ1T and its host Metallosphaera sedula strain MJ1HA, using a variety of electron microscopy techniques, i.e., negative-staining transmission electron microscopy (TEM), quick-freeze deep-etch (QFDE) TEM, and 3D electron tomography. The thickness, unit size, and lattice symmetry of the S-layer of strain MJ1T were different from those of the host archaeon strain MJ1HA. Genomic and transcriptomic analyses highlighted the most highly expressed MJ1T gene for a putative S-layer protein with multiple glycosylation sites and immunoglobulin-like folds, which has no sequence homology to known S-layer proteins. In addition, genes for putative pectin lyase- or lectin-like extracellular proteins, which are potentially involved in symbiotic interaction, were found in the MJ1T genome based on in silico 3D protein structure prediction. Live cell imaging at the optimum growth temperature of 65{degrees}C indicated that cell complexes of strains MJ1T and MJ1HA were motile, but sole MJ1T cells were not. Taken together, we propose a model of the symbiotic interaction and cell cycle of Nanobdella aerobiophila. ImportanceDPANN archaea are widely distributed in a variety of natural and artificial environments, and may play a considerable role in the microbial ecosystem. All of the cultivated DPANN archaea so far need host organisms for their growth, i.e., obligately ectosymbiotic. However, the mechanism of the ectosymbiosis by DPANN archaea is largely unknown. To this end, we performed a comprehensive analysis of the cultivated DPANN archaeon, Nanobdella aerobiophila, using electron microscopy, live cell imaging, transcriptomics, and genomics including 3D protein structure prediction. Based on the results, we propose a reasonable model of the symbiotic interaction and cell cycle of Nanobdella aerobiophila, which will enhance our understanding of the enigmatic physiology and ecological significance of DPANN archaea.

microbiology↗

bioRxiv2023

Antibodies halting motility in Mycoplasma pneumoniae reveal the dynamic nature of the adhesion complex

Mycoplasma pneumoniae is a bacterial wall-less human pathogen and the etiological agent of atypical pneumonia and tracheobronchitis in both adults and children. M. pneumoniae infectivity, gliding motility and adherence to host target respiratory epithelial cells are mediated by adhesin proteins P1 and P40/P90 forming a transmembrane complex that binds to sialylated oligosaccharides human cell ligands. Here we report the cryo-EM structure of P1 bound to the Fab fragment of monoclonal antibody P1/MCA4, which stops gliding and induces detachment of motile M. pneumoniae cells. On the contrary, polyclonal antibodies generated against the N-domain of P1 or against the whole ectodomain of P40/P90 have little or no effects on adhesion or motility. The epitope of P1/MCA4, centred on loop Thr1426-Asp1438 in the small C-terminal domain of P1, is inaccessible to antibodies in the "open" conformation of the adhesion complex, when ready for attachment to sialylated oligosaccharides. Mutations in the highly conserved Engelman motifs found in the transmembrane helix of P40/P90 also alter adhesion and motility. During the attachment/detachment cycle of the adhesion complex, the C-terminal domain of P1 experiences large conformational rearrangements that are hindered by the antibodies against the domain. Interfering with the gliding of mycoplasma cells suggests new ways to confront M. pneumoniae infections.

molecular biology↗