Biology subjects

Anderson, R.

Publications and source records attributed to Anderson, R..

At least 19 recordsLinked to original sources

bioRxiv2026

De Novo Design of Flavoproteins with Controlled Excited State Dynamics

Designing photochemical properties in proteins is a frontier challenge in biomolecular design, which, when realised, will open new avenues in catalysis and biomolecular electronics. Here we demonstrate an integrated computational design framework, supported by ultrafast spectroscopy, combining protein design, quantum mechanical/molecular mechanics molecular dynamics (QM/MM MD) and electronic structure calculations, to control flavin excited states in de novo proteins. Iterative design yields FC-4D2, a flavocytochrome with covalently bound flavin and non-covalently bound heme B and Fl-4D2, where the heme-binding site is removed. Both proteins are highly thermostable, and access all physiologically relevant flavin redox and protonation states, while high-resolution X-ray crystallography confirms the near-[A]ngstrom-level accuracy in design. Incorporating QM/MM MD and linear-response time-dependent density functional theory (LR-TDDFT) into the design workflow enables engineering of a flavin-tryptophan charge-transfer variant, Fl-4D2CT, that modifies the flavin absorption spectrum, substantially alters its redox properties and suppresses fluorescence. Ultrafast studies reveal how protein design reshapes the excited state relaxation timescale and mechanism. Our study establishes a modular strategy for programming flavin photochemistry in designed proteins.

biophysics↗

bioRxiv2026

Convergent Cysteine Enrichment in Diverse Gut Phage Capsids Suggests Gut-Associated Structural Adaptation

BackgroundThe gut environment is hostile to life, yet the human virome, dominated by bacteriophages, persists. Adaptations to the major capsid protein (MCP) may explain this. Phage MCPs conserve the HK97 fold, ideal for detecting convergent features across phage populations. Prior capsid stability research focused on individual phages, limiting broader pattern identification. MethodsMCPs from the Gut Phage Database (GPD) (n=8,478) and INPHARED (n=4,905) were predicted using ProtPhage + Phold and clustered using MMseqs2 (GPD=902 vs INPHARED=606). Structural predictions, conservation analysis, and capsomere modeling were used to characterize cysteine environments. ResultsBioinformatics analysis identified cysteine enrichment in GPD MCPs. Phylogenetic mapping was consistent with convergent evolution of high-cysteine MCPs. Over 50% of cysteines were [≥]90% conserved within and between clusters. Simulated capsomeres showed 83% of cysteines are buried (RSA <10%). ConclusionsThese findings suggest gut phages may have convergently evolved cysteine-based capsid stabilization, with implications for engineering therapeutic phages.

bioinformatics↗

bioRxiv2026

Explainable machine learning reveals an RBP regulatory logic of exon skipping

RNA binding proteins (RBPs) regulate the life cycle of an mRNA, often through RBP-RNA interactions. This life cycle includes splicing, whereby the intronic sequence of a pre-mRNA is removed and the exons are joined together. However, the patterns of RBP binding that lead to different splicing outcomes are still incompletely understood. Here, we build machine learning models from RBP-RNA binding and knockdown RNA-seq data for over 168 RBPs in two cell lines (HepG2 and K562) to better understand the binding patterns that predict exon skipping, the predominant form of alternative splicing in humans. We show that models trained exclusively on RBP binding patterns are indeed predictive and that a more sophisticated machine learning model (XGBoost) outperforms simpler linear models. In addition, we are able to extract a biologically interpretable logic embedded in these models. We show that SHAP, a machine learning explainability technique, captures activating and repressive behavior of RBP binding that is position-specific. In addition, we find that SHAP values are predictive of changes in unseen splicing events and that SHAP interactions between pairs of RBPs are predictive of protein-protein interactions. Our results demonstrate that using machine learning with interpretability techniques can reveal a regulatory logic of RBP binding. By estimating the impact of an RBP binding site on a splicing event, the SHAP values also provide a directly testable scientific hypothesis. We anticipate that models designed around biological processes and focused on interpretability will yield actionable biological insights both in splicing and genomics generally.

systems biology↗

bioRxiv2025

A distal promoter and aberrant splicing enable canonical translation of out-of-frame proteins in Huntington's disease

Expanded CAG trinucleotide repeats cause more than a dozen neurodegenerative diseases, including Huntingtons disease (HD). In several disorders, these repeats are translated in multiple reading frames without identifiable AUG start codons. This process, called repeat-associated non-AUG (RAN) translation, generates aggregation-prone proteins, but its molecular basis remains unclear. Here, using affinity capture of CAG-repeat-containing RNAs, we identify a previously unannotated promoter ~33 kb upstream of the HTT gene. Transcripts initiating from this promoter undergo repeat-length-dependent aberrant splicing into exon 1 of the canonical HTT, embedding the CAG repeat in AUG-initiated frames encoding polyalanine and polyserine proteins. Comparative genomics indicates that this upstream promoter is primate-specific, helping explain inconsistencies across rodent models. Our findings establish a direct, AUG-dependent, splicing-mediated mechanism for out-of-frame repeat proteins in HD, expose critical gaps in current animal models, and identify novel splice junctions as potential therapeutic targets.

molecular biology↗

bioRxiv2025

The road less travelled: Exploring the genomic characteristics and antimicrobial resistance potential of Acinetobacter baumannii from the indigenous Orang Asli community in Peninsular Malaysia

Acinetobacter baumannii is widely recognized as a multidrug-resistant pathogen, but with most public genome datasets biased toward hospital-derived isolates. Little is thus known about A. baumannii isolates from healthy individuals from the community. This study analysed genome sequences from nine A. baumannii isolates obtained from the upper respiratory tract of healthy individuals of the indigenous Orang Asli community in their rural settlements located in the east coast of Peninsular Malaysia. Genomic analysis revealed all nine A. baumannii isolates to be genetically distinct and included three new sequence types (STs) under the Pasteur scheme and six novel STs under the Oxford scheme. Notably, one isolate, A. baumannii 19064, belonged to Global Clone 8 (GC8), a lineage associated with clinical infections. Core genome phylogeny indicated that the Orang Asli community isolates were interleaved with several non-GC clinical isolates from the tertiary hospital within the same state. This is suggestive of the potential of these community isolates to cause infections under conducive conditions. This is also attested by the identification of several virulence factors in their genomes. All nine isolates carried various intrinsic blaOXA-51-like class D {beta}-lactamase genes and class C Acinetobacter-derived cephalosporinase (ADC) blaADC genes but remained susceptible to meropenem. Two isolates, A. baumannii 19053 and 19062, were tetracycline resistant but minocycline susceptible and harboured the tet(39)-tetR gene pair within mobile pdif modules located on distinct Rep_3 family plasmids. Only one isolate, A. baumannii 19055, is plasmid-free; the rest mainly harboured cryptic Rep_3-type plasmids, often containing identifiable pdif modules. These findings highlight the clinical relevance of A. baumannii strains residing in healthy individuals, particularly in isolated communities that are seldom accessible to public health. Despite their remote location, the Orang Asli A. baumannii isolates possess virulence factors and antibiotic resistance genes similar to those found in hospital settings. This underscores the importance of genomic surveillance of commensal pathogens, and taking this road which is less travelled can help inform broader epidemiological insights and guide future public health strategies.

microbiology↗

bioRxiv2025

Maternal time budgets of feral goats at high latitudes in northwest Europe.

Reproduction is energetically expensive for mammals, and especially so during lactation. In large-brained mammals such a primates, females invest heavily in additional feeding to fuel the costs of lactation. The evidence is more mixed in ruminant ungulates. We examine the foraging costs of lactating female feral goats living under environmentally challenging conditions in the northwest of Scotland where these effects are most likely to be exaggerated. We show, using data from three separate studies, that, compared to matched non-lactating females, lactating females do increase the time devoted to foraging, but only to a limited extent that is well below the theoretical requirements of their kids. Although they do not alter their diet, lactating females spend more time in shelter and at lower altitudes in order to reduce thermoregulatory costs. At high latitudes, the rate at which kids grow is such that females cannot afford to extend lactation much beyond two months. This will inevitably set a limit on ungulates capacity to produce large-brained offspring. HighlightsO_LILactation is costly, obliging females to increase food intake or draw on body fat C_LIO_LIAt high latitudes, goats increase foraging, but not enough to meet kids demands C_LIO_LIFemales do not forage on richer foods, but they do try to minimise thermal costs C_LIO_LIAs a result, females have high mortality after weaning when forage quality is poor C_LI

animal behavior and cognition↗

bioRxiv2025

Attenuation of mosaic aneuploidy and erroneous first mitotic division of human embryos

Human reproduction is inherently inefficient1 and 1 in 6 people worldwide suffer infertility. In vitro fertilisation (IVF) can help some couples conceive, but only ~30% of cycles are successful. One factor affecting IVF efficacy is mitotic-origin (mosaic) aneuploidy in which embryos contain a mixture of cells with different numbers of chromosomes2. We previously showed that chromosome segregation error phenotypes are frequent in the first mitotic division of the human embryo3. However, the cause of these errors and impact on daughter cell karyotype is unknown. Here, using live chromosome imaging and next generation sequencing we show that activation of the microtubule depolymerase KIF2C reduces chromosome segregation errors and mitotic-origin aneuploidy at the 2-cell stage. The number of first divisions that show alternative cleavage patterns (associated with failed embryo development in IVF clinics) are also reduced with KIF2C activation. Our findings demonstrate that modulation of microtubule dynamics is a potential therapeutic route to improving human embryo quality and IVF outcomes.

cell biology↗

bioRxiv2024

A genetically encoded fluorescent reporter for polyamines

Polyamines are abundant and evolutionarily conserved metabolites that are essential for life. Dietary polyamine supplementation extends life-span and health-span. Dysregulation of polyamine homeostasis is linked to Parkinsons disease and cancer, driving interest in therapeutically targeting this pathway. However, measuring cellular polyamine levels, which vary across cell types and states, remains challenging. We introduce a first-in-class genetically encoded polyamine reporter for real-time measurement of polyamine concentrations in single living cells. This reporter utilizes the polyamine-responsive ribosomal frameshift motif from the OAZ1 gene. We demonstrate broad applicability of this approach and reveal dynamic changes in polyamine levels in response to genetic and pharmacological perturbations. Using this reporter, we conducted a genome-wide CRISPR screen and uncovered an unexpected link between mitochondrial respiration and polyamine import, which are both risk factors for Parkinsons disease. By offering a new lens to examine polyamine biology, this reporter may advance our understanding of these ubiquitous metabolites and accelerate therapy development.

cell biology↗

bioRxiv2024

Characterizing population structure and documenting rapid loss of genetic diversity in Chiricahua Leopard Frogs (Lithobates chiricahuensis) with high throughput microsatellite genotyping

The use of molecular markers to assess genetic diversity has become a common component of recovery action plans for threatened and endangered species. In this study, we use an unusually large number of microsatellite markers (N=91) to characterize the genetic variation of Chiricahua Leopard Frogs (Lithobates chiricahuensis) across their range in order to understand their distribution of genetic variation, identify genetic bottlenecks, and measure genetic changes over time in a single, highly-managed population. Populations were best divided into three genetically distinct clusters, with the southeastern Arizona and New Mexico populations forming distinct genetic clusters. While there is moderate genetic variation distributed across the sampled populations, each population on its own shows relatively low allelic diversity. Most populations displayed strong genetic signals of recent genetic bottlenecks or a deficiency of heterozygous genotypes that is typically associated with frequent inbreeding. Populations that have a history of no management through translocations harbored the greatest number of unique alleles and overall allelic richness, especially in a subset of the Mexican populations. Finally, long-term cohort sampling at one specific site (the Southwestern Research Station in Portal, Arizona) allowed us to demonstrate how rapidly genetic diversity can decrease across a matter of years in a population with few founders. This work shows how microsatellite markers can provide important context for conservation agencies, but even a large suite of markers beyond what is typical may not be enough for populations that are extremely bottlenecked and have low levels of standing genetic diversity.

genetics↗

bioRxiv2024

Phylogenomics of novel clones of Aeromonas veronii recovered from a freshwater lake reveals unique biosynthetic gene clusters

Aquatic ecosystems are important reservoirs for clinically relevant pathogens and antimicrobial resistance genes, thus present a significant risk to global health. Here, we assessed the phylogenomics of Aeromonas veronii (A. veronii) recovered from Lake Wilcox in Ontario using a combination of morphological, biochemical, and whole-genome sequencing (WGS) techniques. Eleven distinct bacterial colonies were isolated and identified as A. veronii (n=9), and two other Aeromonas species (A. caviae and A. allosaccharophila), with significant discrepancies noted between biochemical and WGS identification methods. Of note, 67% (n=6/9) of A. veronii isolates were human pathogens (Pathogenicity score [≥] 0.50). The genomic analysis revealed high genetic diversity among the A. veronii isolates, including the discovery of 41 novel alleles and seven new sequence types (ST) suggesting the lake as a reservoir for multiple human pathogenic clones of this bacterium. The comparison of the newly isolated and sequenced A. veronii with 214 A. veronii genomes revealed significant genetic diversity and suggests potential broad geographical dissemination of strains. Chromosomal genes (OXA-912 and cphA [cphA3, cphA4, cphA7]) genes encoding resistance to {beta}-lactamases were detected in all isolates. Human and non-human pathogenic strains of A. veronii differed in their virulence gene content, with type III secretion systems being associated with human pathogenic isolates. Mobilome analysis revealed the absence of plasmids in A. veronii isolates and the presence of 13 intact the great majority of which were P22-like (Peduoviridae) phages, and nine different insertion sequence families. Novel biosynthetic gene clusters were identified and characterized, indicating the potential for unique secondary metabolite production in A. veronii with different pathogenic potential. Overall, this study underscores the importance of continuous surveillance of aquatic ecosystems for the presence of pathogens, contributing to our understanding of their evolution, potential for human pathogenicity, and the ecological roles of their genetic elements.

microbiology↗

bioRxiv2024

Proteasome hyperactivation rewires the proteome enhancing stress resistance, proteostasis, lipid metabolism and ERAD in C. elegans.

Age-related proteinopathies, including Alzheimers and Parkinsons disease, are driven by the toxic accumulation of misfolded proteins, particularly intrinsically disordered proteins (IDPs), that overwhelm cellular proteostasis. The proteasome is responsible for the clearance of these proteins, but it is unclear why it fails to do so in these diseases. Here, we report a novel strategy employing a C. elegans model with a hyperactive 20S proteasome (3{Delta}N) to achieve selective activation. This activation robustly enhances the degradation of IDPs and misfolded proteins, markedly reduces oxidative damage, and significantly improves ER-associated degradation (ERAD). Notably, aggregation-prone substrates, such as endogenous vitellogenins and human alpha-1 antitrypsin (ATZ), are efficiently cleared. Proteomic and transcriptomic reprogramming reveals systemic adaptations characterized by increased protein turnover and enhanced oxidative stress resistance, independent of superoxide dismutases. Strikingly, proteasome hyperactivation extends lifespan and enhances stress resistance independently of known proteostasis pathways including the canonical unfolded protein response mediated by xbp-1. Our findings provide substantial support for a "20S pathway" of proteostasis that alleviates protein aggregation and oxidative stress, offering a promising therapeutic strategy for neurodegenerative diseases TeaserEnhanced disordered protein clearance by the 20S proteasome in worms prevents toxic protein buildup and promotes stress resistance and longevity.

cell biology↗

bioRxiv2023

Adaptive gene loss in the common bean pan-genome during range expansion and domestication

The common bean (Phaseolus vulgaris L.) is a crucial grain legume crop [1,2] whose life history offers an ideal evolutionary model to identify and study adaptive variants in wild and domestication populations [3]. Here we present the first common bean pan-genome based on five high-quality genomes and whole-genome reads representing 339 genotypes. We found [~]243 Mb of additional sequences containing 7,495 protein-coding genes missing from the reference, constituting 51% of the total presence/absence variations (PAVs). There were more putatively deleterious mutations in PAVs than core genes, probably reflecting the lower effective population size of PAVs as well as fitness advantages due to the purging effect of gene loss. Our results suggest strong pan-genome shrinkage occurred during wild range expansion from Mexico to South America, with more PAV loss per individual in Andean vs Mesoamerican populations. Selection signatures during wild spreading and domestication were also associated with PAV loss involved in important adaptive traits. Our findings provide evidence that partial or complete gene loss was a key adaptive trait leading to localized and genome-wide reductions. This novel result has major implications for the understanding of the process of plant adaptation and claims for a paradigm shift in evolutionary genetics. Moreover, the common bean pan-genome is a valuable resource for food legume research and breeding towards climate change mitigation, and sustainable agriculture.

evolutionary biology↗

bioRxiv2023

Timing the Evolution of Phosphorus-Cycling 1 Enzymes Through Geological Time

SUMMARY PARAGRAPHPhosphorus plays a crucial role in controlling biological productivity, but geological estimates of phosphate concentrations in the Precambrian ocean, during lifes origin and early evolution, vary over several orders of magnitude1-10. While reduced phosphorus species may have served as alternative substrates to phosphate11, their bioavailability on the early Earth remains unknown. Here, we reconstruct the phylogenomic record of life on Earth and find that phosphate transporting genes (pnas) evolved in the mid-Archean (ca. 3.2 Ga) and are consistent with phosphate concentrations above modern levels (>3 M). The first gene optimized for low phosphate levels (pstS; <1 M) appeared around 2.9 Ga. Most enzymatic pathways for metabolising reduced phosphorus emerged and expanded across the tree of life in the Neoarchean to Paleoproterozoic (ca. 2.6 to 1.8 Ga). This includes phosphonate-catabolising CP-lyases, phosphite-oxidising pathways and hypophosphite-oxidising pathways. CP-lyases are particularly abundant in dissolved phosphate concentrations below 0.1 M. Our results thus indicate declining phosphate levels through the Archean, possibly linked to increasing deposition of phosphate-scavenging iron oxides, which may have limited productivity. However, reduced phosphorus species did not become widely used until after the Paleoproterozoic Great Oxidation Event (2.3 Ga), possibly linked to an expansion of the biosphere at that time.

evolutionary biology↗

bioRxiv2023

Antibodies generated in vitro and in vivo elucidate design of a thermostable ADDomer COVID-19 nasal nanoparticle vaccine

COVID-19 continues to damage populations, communities and economies worldwide. Vaccines have reduced COVID-19-related hospitalisations and deaths, primarily in developed countries. Persisting infection rates, and highly transmissible SARS-CoV-2 Variants of Concern (VOCs) causing repeat and breakthrough infections, underscore the ongoing need for new treatments to achieve a global solution. Based on ADDomer, a self-assembling protein nanoparticle scaffold, we created ADDoCoV, a thermostable COVID-19 candidate vaccine displaying multiple copies of a SARS-CoV-2 receptor binding motif (RBM)-derived epitope. In vitro generated neutralising nanobodies combined with molecular dynamics (MD) simulations and electron cryo-microscopy (cryo-EM) established authenticity and accessibility of the epitopes displayed. A Gigabody comprising multimerized nanobodies prevented SARS-CoV-2 virion attachment with picomolar EC50. Antibodies generated by immunising mice cross-reacted with VOCs including Delta and Omicron. Our study elucidates nasal administration of ADDomer-based nanoparticles for active and passive immunisation against SARS-CoV-2 and provides a blueprint for designing nanoparticle reagents to combat respiratory viral infections.

biochemistry↗

bioRxiv2023

An Innovative Non-Hormonal Strategy Targeting Redox Active Metals to Down-Regulate Estrogen-, Progesterone-, Androgen- and Prolactin-Receptors in Breast Cancer

Estrogen receptor- (ER-) is a key driver of breast cancer (BC) targeted by tamoxifen. However, tamoxifen resistance is a major problem. An important mechanism of resistance is the activation of EGFR/HER2/HER3 signaling and other hormone receptors (androgen receptor (AR), progesterone receptor (PR), prolactin receptor (PRL-R)) that intrinsically activate ER-. Hence, therapeutics targeting multiple receptors, rather than ER- alone, would be extremely useful and may overcome tamoxifen resistance. This study examined the activity of redox-active di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) and di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), on the expression and activation of crucial hormone receptors, their co-factors, and key resistance pathways in ER--positive BC. Strikingly, DpC differentially regulated 106 estrogen-response genes with Sankey diagram analysis demonstrating this was linked to decreased mRNA levels of 4 central hormone receptors involved in BC pathogenesis, namely ER, PR, AR, and PRL-R. Mechanistic dissection demonstrated that due to DpC and Dp44mT binding metal ions, these agents caused a pronounced decrease in ER-, AR, PR, and PRL-R protein expression. Ablation of the metal-binding site in the thiosemicarbazone totally prevented its suppressive activity, demonstrating a unique non-hormonal mechanism. DpC and Dp44mT also inhibited EGFR, HER2, and HER3 activation, their downstream signaling, and the expression of co-factors that promote ER- transcriptional activity, including SRC3, NF-{kappa}B p65, and SP1. In vivo, DpC was highly tolerable and effectively inhibited ER--positive BC growth. In conclusion, through a bespoke non-hormonal mechanism targeting redox active metals, Dp44mT and DpC disrupt multiple key inter-receptor interactions between PR, AR, PRL-R, and tyrosine kinases that act with ER- to promote BC, constituting an innovative therapeutic approach.

cancer biology↗

bioRxiv2023

A microRNA expression signature in infant t(4;11) MLL-AF4+ BCP-ALL uncovers novel therapeutic targets

Infants and children with MLL-AF4+ leukemia have an urgent need for more efficient and less aggressive therapy. In this study, we studied three microRNAs that are downregulated in MLL-AF4+ B-cell precursor acute lymphoblastic leukemia (BCP-ALL): miR-194, miR-99b and miR-125a-5p. When overexpressed, all three microRNAs impaired the survival of MLL-AF4+ leukemic blasts and the maintenance of MLL-AF4+ BCP-ALL. We identified microRNA target genes responsible for this phenotype that are upregulated in MLL-AF4+ BCP-ALL: CA5B, PPP3CA and PPP2R5C. Using CRISPR-Cas9 and specific inhibitors, we confirmed that CA5B, PPP3CA and PPP2R5C downregulation/inhibition severely compromised the proliferation and survival of MLL-AF4+ leukemic blasts. Importantly, CA5B, PPP3CA and PP2A inhibition by acetazolamide, tacrolimus and LB-100, respectively, showed high toxicity towards MLL-AF4+ leukemic blasts and reduced leukemia burden in vivo. This study highlights how the unique microRNA expression signature of patients with MLL-AF4+ BCP-ALL can be used to uncover novel therapeutic avenues and accelerate drug repurposing. Statement of significanceThere is an urgent need to identify novel therapeutic avenues for patients with MLL-AF4+ BCP-ALL that are more effective and less aggressive. This study identified three clinically available drugs (acetazolamide, tacrolimus and LB-100) with high and selective toxicity towards MLL-AF4+ leukemic cells.

cancer biology↗

bioRxiv2022

Photovoltaic enzymes by design and evolution

The global energy crisis challenges us to develop more efficient strategies for the sustainable production of energy. Given the excellent efficiency of the natural photosynthetic apparatus, biohybrid photovoltaic devices present an attractive solution for solar energy conversion. However, their composition, stability, and complexity can limit their inclusion into photovoltaic devices. Here, we combined computational design and directed evolution to overcome these limitations and create tailor-made photoenzymes. Photo-biocatalysts were designed by introducing photosensitizer binding sites into heme-containing helical bundle proteins. The designed binding sites were specific for the target photosensitizer and readily transplanted into other helical bundles. The best design was highly evolvable and reached nanomolar ligand affinity after mutagenesis and screening. The evolved enzyme generated 2.6 times higher photocurrents than the photosensitizer alone, primarily driven by increased photostability. Evolvability is a unique advantage of our protein-based approach over abiological photovoltaic and will be critical to developing efficient biohybrid systems. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/521207v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@2b6031org.highwire.dtl.DTLVardef@1b83f69org.highwire.dtl.DTLVardef@14b39a4org.highwire.dtl.DTLVardef@1b569bb_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2022

Cellular production of a de novo membrane cytochrome

Heme-containing integral membrane proteins are at the heart of many bioenergetic complexes and electron transport chains. The importance of these electron relay hubs across biology has inspired the design of de novo proteins that recreate their core features within robust, versatile and tractable protein folds. To this end, we report here the computational design and in-cell production of a minimal diheme membrane cytochrome which successfully integrates into the cellular membrane of live bacteria. This synthetic construct emulates a four-helix bundle found in modern respiratory complexes but has no sequence homology to any polypeptide sequence found in nature. The two b-type hemes, which appear to be recruited from the endogenous heme pool, have distinct split redox potentials with values close to those of natural membrane-spanning cytochromes. The purified protein can engage in rapid biomimetic electron transport with small molecules, with other redox proteins, and with biologically-relevant diffusive electron carriers. We thus report an artificial membrane metalloprotein with the potential to serve as a functional module in electron transfer pathways in both synthetic protocells and living systems.

biochemistry↗