Biology subjects

Yano, H.

Publications and source records attributed to Yano, H..

27 records · Page 2Linked to original sources

bioRxiv2022

Strand-biased circularizing integrative elements spread tmexCD-toprJ gene clusters encoding RND-type multidrug efflux pumps by repeated transpositions

Antimicrobial resistance genes (ARGs) are associated with mobile genetic elements (MGEs) that conscript useful genes into the human-microbe and microbe-microbe battlefields. Thus, under intense selective pressure, ARGs have been constantly adapting and evolving, spreading among microbes. tmexCD-toprJ gene clusters, which encode resistance-nodulation-cell division (RND)-type efflux pumps, confer multidrug-resistance to clinically important antimicrobials, including tigecycline. Noteworthily, these gene clusters have emerged in gram-negative bacteria in humans, animals, and the environment worldwide by MGE-mediated transfer. Here we show a hidden MGE, strand-biased circularizing integrative element (SE), that is recently recognized to mediate transpositions of ARGs, associated with the spread of tmexCD-toprJ gene clusters. We identified multidrug-resistant isolates of Aeromonas species in a water environment in Vietnam that harbored multiple copies of tmexCD-toprJ in their chromosomes that were associated with SEs. In particular, Aeromonas hydrophila NUITM-VA1 was found to harbor two copies of a novel variant of tmexC3.3D3.3-topJ1 within cognate SEs, whereas Aeromonas caviae NUITM-VA2 harbored four copies of a novel variant of tmexC2D2.3-topJ2 within cognate SEs. Based on the nature of SE to incorporate a neighboring sequence into the circular form and reinsert it into target sites during transposition, we identified the order of intragenomic movements of tmexCD-toprJ gene clusters. Altogether, our findings suggest that most known subgroups of tmexCD-toprJ and their subvariants underwent transpositions among bacterial chromosomes and plasmids via SEs. Hence, a tmexCD-toprJ gene cluster ancestor may have been initially mobilized via SE, subsequently spreading among bacteria and evolving in new hosts.

microbiology↗

bioRxiv2022

Unique genomic sequences in novel Mycobacterium avium subsp. hominissuis lineage enabled fine scale tracing the transmission route during pig movement

Mycobacterium avium subsp. hominissuis (MAH) is one of the most prevalent mycobacteria causing non-tuberculous mycobacterial disease in humans and animals. Of note, MAH is a major cause of mycobacterial granulomatous mesenteric lymphadenitis outbreaks in pig populations. To determine the precise source of infection of MAH in a pig farm and to clarify the epidemiological relationship among pig, human and environmental MAH lineages, we collected 50 MAH isolates from pigs reared in Japan and determined draft genome sequences of 30 isolates. A variable number of tandem repeat analysis revealed that most pig MAH isolates in Japan were closely related to North American, European and Russian human isolates but not to those from East Asian human and their residential environments. Historical recombination analysis revealed that most pig isolates could be classified into SC2/4 and SC3, which contain MAH isolated from pig, European human and environmental isolates. Half of the isolates in SC2/4 had many recombination events with MAH lineages isolated from humans in East Asia. To our surprise, four isolates belonged to a new lineage (SC5) in the global MAH population. Members of SC5 had few footprints of inter-lineage recombination in the genome, and carried 80 unique genes, most of which were located on lineage specific-genomic islands. Using unique genetic features, we were able to trace the putative transmission route via their host pigs. Together, we clarify the possibility of species-specificity of MAH in addition to local adaptation. Our results highlight two transmission routes of MAH, one exposure on pig farms from the environment and the other via pig movement. Moreover, our study also warns that the evolution of MAH in pigs is influenced by MAH from patients and their residential environments, even if the MAH are genetically distinct. HighlightsO_LIVariable number of tandem repeat analysis of Mycobacterium avium subsp. hominissuis (MAH) isolated from pigs (n=50) were conducted. C_LIO_LIDraft genome sequences of MAH (n=30) and genome analysis were conducted. C_LIO_LIPig MAHs were genetically far from East Asian human isolates and close to those of Western countries. C_LIO_LINovel MAH lineage which were transmitted farms by pig movement was found. C_LIO_LIHuman MAH isolates influenced the evolution of pig isolates. C_LI

microbiology↗

bioRxiv2021

Genome-wide association study reveals putative bacterial risk factors for cavitary Mycobacterium avium complex lung disease

Mycobacterium avium complex (MAC) lung disease is a slowly progressive disease, and its increasing incidence has garnered increased research interests. Cavitary MAC lung disease is associated with a higher mortality rate. Though genetic studies have unraveled the human risk factors, the role of microbial factors on pathogenesis behind the disease remains elusive. In this study, M. avium isolates were collected from sputum specimens of 109 distinct Japanese patients with or without a cavity (60 with a cavity and 49 without cavity) in a hospital located in Osaka prefecture. M. avium genomes were sequenced and searched for DNA motifs associated with cavity formation using a bacterial GWAS. Excluding known macrolide resistance mutations; cavity formation was found to be primarily associated with variants of cytochrome P450 of the CYP139 family, type I polyketide synthase Pks13, and the promoter region of an operon encoding membrane-anchored protease FtsH and folate synthesis pathway enzymes. Cavity risk variants at these three loci were frequent in the MahEastAsia2 lineage among the six lineages detected in M. avium global populations. Furthermore, the study demonstrated a correlation between the cavity risk promoter variant and increased sulfamethoxazole/trimethoprim resistance. Together, these findings suggest that natural variation in the biosynthesis and maintenance processes of M. avium membrane components influences the disease type of MAC lung disease. Although further validation is needed, the bacterial genetic markers listed in the present study could contribute to prognosis prediction based on bacterial genotyping and help develop treatment strategies in the future. IMPORTANCENontuberculous mycobacterial lung disease is of great concern in countries with an increasingly aging population. The disease types can largely be classified into non-cavitary nodular bronchiectasis and cavitary diseases (fibrocavitary, nodular bronchiectasis with cavity) that require different treatment strategies depending on the causal agents. Several studies have reported human risk factors for the disease; however, little efforts were made to investigate the risk factors in nontuberculous mycobacteria. Moreover, molecular genetics experiments have been difficult to search for virulence factors in M. avium, which the population genomics approaches could overcome. Here, the GWAS results suggested variants in three chromosomal loci associated with mycobacterial membrane components as risk factors for cavitary MAC lung disease. These findings could help develop treatment strategies for MAC lung disease in the future.

microbiology↗

bioRxiv2021

Copy-out-paste-in transposition of a Tn6283-like integrative element assists interspecies antimicrobial resistance gene transfer from Vibrio alfacsensis

The exchange of antimicrobial resistance (AMR) genes between aquaculture and terrestrial microbial populations has emerged as a serious public health concern. However, the nature of the mobile genetic elements in marine bacteria is poorly documented. To gain insight into the genetic mechanisms underlying AMR gene transfer from marine bacteria, we mated a multidrug-resistant Vibrio alfacsensis strain with an Escherichia coli strain, and then determined the complete genome sequences of the donor and the transconjugant strains. Sequence analysis revealed a conjugative multidrug resistance plasmid in the donor strain, which was integrated into the chromosome of the recipient. The plasmid backbone in the transconjugant chromosome was flanked by two copies of a 7.1 kb unclassifiable integrative element harboring a {beta}-lactamase gene. The 7.1 kb element and the previously reported element Tn6283 share four coding sequences, two of which encode the catalytic R-H-R-Y motif of tyrosine recombinases. Polymerase chain reaction and sequencing experiments revealed that these elements generate a circular copy of one specific strand without leaving an empty site on the donor molecule, in contrast to the movement of integron gene cassettes or ICE/IMEs discovered to date. These elements are termed SEs (strand-biased circularizing integrative elements): SE-6945 (the 7.1 kb element) and SE-6283 (Tn6283). The copy number and location of SE-6945 in the chromosome affected the antibiotic resistance levels of the transconjugants. SEs were identified in the genomes of other Vibrio species. Overall, these results suggest that SEs are involved in the spread of AMR genes among marine bacteria.

microbiology↗

bioRxiv2021

Genomic features of Mycobacterium avium subsp. hominissuis isolated from pigs in Japan.

Mycobacterium avium subsp. hominissuis (MAH) is one of the most important agents causing non-tuberculosis mycobacterial infection in humans and pigs. Genome analysis on MAH of human isolates has been proceeding, however, those of pigs are limited despite its potential source of infection to human. In the current study, we obtained 30 draft genome sequences of MAH of pigs reared in Japan. The 30 draft genomes consisted of 4,848,678 - 5,620,788 bp length, 4,652 - 5,388 coding genes and 46 - 75 (Med: 47) tRNAs. All isolates had restriction modification associated genes and 185 - 222 predicted virulence genes. Two isolates had tRNA arrays and one isolate had a clustered regularly interspaced short palindromic repeat (CRISPR) region. Our results will be useful for evaluation of the ecology of MAH by providing a foundation for genome-based epidemiological studies.

microbiology↗

bioRxiv2021

Genome-wide association study of gastric cancer- and duodenal ulcer-derived Helicobacter pylori strains reveals discriminatory amino acid differences and novel oncoprotein candidates

Genome-wide association studies (GWASs) can reveal genetic variations associated with a phenotype in the absence of any hypothesis of candidate genes. The problem of false-positive sites linked with the responsible site might be bypassed in bacteria with a high homologous recombination rate, such as Helicobacter pylori, which causes gastric cancer (GC). We conducted a GWAS followed by regression-based prediction of GC and duodenal ulcer H. pylori strains. We identified 14 single nucleotide polymorphisms (11 amino acid changes) that, combined, allowed effective disease discrimination. They were often informative of the underlying molecular mechanisms, such as electric charge alteration at the ligand-binding pocket, alteration in subunit interaction, and mode-switching of DNA methylation. We also identified three novel virulence factors/oncoprotein candidates. These results provide both defined targets for further informatic and experimental analyses to gain insights into GC pathogenesis and a basis for identifying a set of biomarkers for application in clinical settings.

physiology↗

bioRxiv2019

The effects of terminal tagging on homomeric interactions of the sigma 1 receptor

The sigma 1 receptor ({sigma}1R) has been implicated in cancers, neurological disorders, and substance use disorders. Yet, its molecular and cellular functions have not been well-understood. Recent crystal structures of {sigma}1R reveal a single N-terminal transmembrane segment and C-terminal ligand-binding domain, and a trimeric organization. Nevertheless, outstanding issues surrounding the functional or pharmacological relevance of {sigma}1R oligomerization remain, such as the minimal protomeric unit and the differentially altered oligomerization states by different classes of ligands. Western blot (WB) assays have been widely used to investigate protein oligomerizations. However, the unique topology of {sigma}1R renders several intertwined challenges in WB. Here we describe a WB protocol without temperature denaturization to study the ligand binding effects on the oligomerization state of {sigma}1R. Using this approach, we observed unexpected ladder-like incremental migration pattern of {sigma}1R, demonstrating preserved homomeric interactions in the detergent environment. We compared the migration patterns of intact {sigma}1R construct and the C-terminally tagged {sigma}1R constructs, and found similar trends in response to drug treatments. In contrast, N-terminally tagged {sigma}1R constructs show opposite trends to that of the intact construct, suggesting distorted elicitation of the ligand binding effects on oligomerization. Together, our findings indicate that the N-terminus plays an important role in eliciting the impacts of bound ligands, whereas the C-terminus is amenable for modifications for biochemical studies.

biochemistry↗

bioRxiv2019

Inoculum size effects in blaIMP-6 and plasmid-mediated quinolone resistance gene-positive Enterobacteriaceae in Japan

The aim of this study was to examine the resistance genes in clinical isolates which produced IMP-6 type metallo-{beta}-lactamase lactamase (MBL) and had mildly reduced susceptibilities to levofloxacin and/or amikacin. The inoculum size effect was also assessed. A total of 14 Enterobacteriaceae isolates (2 Escherichia coli and 12 Klebsiella pneumoniae) which produced IMP-6 MBL, and had mild increases in their MICs for levofloxacin and amikacin were examined. Thirteen out of 14 isolates harbored CTX-M-2, with the remaining isolate co-harboring CTX-M-2 and CTX-M-1 as ESBLs. All isolates carried one or more PMQRs; aac(6')-Ib-cr was the most prevalent (92.8%), followed by oqxA (64.3%), qnrS (42.9%), oqxAB (21.4%), and qnrB (14.3%). The inoculum size effects were significant in all strains for meropenem, 13 for imipenem, 7 for levofloxacin, and 3 for amikacin. Conjugation was successfully performed with 8 isolates and 11 strains were obtained. Eleven of the experimental strains (100%), and 8 strains (72.7%) showed inoculum size effects for meropenem and imipenem, respectively. No inoculum size effect was seen for levofloxacin. Four strains harbored qnr genes and 2 strains harbored qnr genes and QRDR mutations concurrently. blaIMP-6 positive Enterobacteriaceae with mildly reduced susceptibilities to levofloxacin and/or amikacin also harbored at least one plasmid-mediated drug resistance gene. These represent an unrecognized threat, capable of compromising the in vitro activity of many classes of antimicrobial agents. We conclude that IMP-6 MBL plays an important role in decreasing the MIC for carbapenems, whereas qnr does not for levofloxacin.

microbiology↗

bioRxiv2017

Emerging patterns of plasmid-host coevolution that stabilize antibiotic resistance

Multidrug resistant bacterial pathogens have become a serious global human health threat, and conjugative plasmids are important drivers of the rapid spread of resistance to last-resort antibiotics. Whereas antibiotics have been shown to select for adaptation of resistance plasmids to their new bacterial hosts, or vice versa, a general evolutionary mechanism has not yet emerged. Here we conducted an experimental evolution study aimed at determining general patterns of plasmid-bacteria evolution. Specifically, we found that a large conjugative resistance plasmid follows the same evolutionary trajectories as its non-conjugative mini-replicon in the same and other species. Furthermore, within a single host-plasmid pair three distinct patterns of adaptive evolution led to increased plasmid persistence: i) mutations in the replication protein gene (trfA1); ii) the acquisition by the resistance plasmid of a transposon from a co-residing plasmid encoding a putative toxin-antitoxin system; iii) a mutation in the hosts global transcriptional regulator gene fur. Since each of these evolutionary solutions individually have been shown to increase plasmid persistence in other plasmid-host pairs, our work points towards common mechanisms of plasmid stabilization. These could become the targets of future alternative drug therapies to slow down the spread of antibiotic resistance.

evolutionary biology↗