scholarly journals Phylogenetic and structural diversity of aromatically dense pili from environmental metagenomes

2019 ◽  
Author(s):  
M. S. Bray ◽  
J. Wu ◽  
C.C. Padilla ◽  
F. J. Stewart ◽  
D. A. Fowle ◽  
...  
Keyword(s):  
Amino Acids ◽  
Electron Transfer ◽  
Microbial Respiration ◽  
Aromatic Amino Acids ◽  
Structural Diversity ◽  
Type Iv Pili ◽  
Extracellular Electron Transfer ◽  
Environmental Distribution ◽  
Type Iv ◽  
Genes Encoding

SummaryElectroactive type IV pili, or e-pili, are used by some microbial species for extracellular electron transfer. Recent studies suggest that e-pili may be more phylogenetically and structurally diverse than previously assumed. Here, we used updated aromatic density thresholds (≥9.8% aromatic amino acids, ≤22-aa aromatic gaps, and aromatic amino acids at residues 1, 24, 27, 50 and/or 51, and 32 and/or 57) to search for putative e-pilin genes in metagenomes from diverse ecosystems with active microbial metal cycling. Environmental putative e-pilins were diverse in length and phylogeny, and included truncated e-pilins inGeobacterspp., as well as longer putative e-pilins in Fe(II)-oxidizingBetaproteobacteriaandZetaproteobacteria.Originality and SignificanceElectroactive pili (e-pili) are used by microorganisms to respire solid metals in their environment through extracellular electron transfer. Thus, e-pili enable microbes to occupy specific environmental niches. Additionally, e-pili have important potential for biotechnological applications. Currently the repertoire of known e-pili is small, and their environmental distribution is largely unknown. Using sequence analysis, we identified numerous genes encoding putative e-pili from diverse anoxic, metal-rich ecosystems. Our results expand the diversity of putative e-pili in environments where metal oxides may be important electron acceptors for microbial respiration.

scholarly journals Direct Extracellular Electron Transfer of the Geobacter sulfurreducens Pili Relevant to Interaromatic Distances

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Chuanjun Shu ◽  
Qiang Zhu ◽  
Ke Xiao ◽  
Yue Hou ◽  
Haibo Ma ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Type Iv Pili ◽  
Geobacter Sulfurreducens ◽  
Transfer Reactions ◽  
Extracellular Electron Transfer ◽  
Aromatic Residues ◽  
New Class ◽  
Type Iv ◽  
Pilin Subunit ◽  
Potential Applications

Microorganisms can transfer electrons directly to extracellular acceptors, during which organic compounds are oxidized to carbon dioxide. One of these microbes, Geobacter sulfurreducens, is well known for the “metallic-like” conductivity of its type IV pili. However, there is no consensus on what the mechanism for electron transfer along these conductive pili is. Based on the aromatic distances and orientations of our predicted models, the mechanism of electron transfer in the Geobacter sulfurreducens (GS) pili was explored by quantum chemical calculations with Marcus theory of electron transfer reactions. Three aromatic residues from the N-terminal α-helix of the GS pilin subunit are packed together, resulting in a continuous pi-pi interaction chain. The theoretical conductance (4.69 μS/3.85 μS) of the predicted models is very similar to that in the experiments reported recently (3.40 μS). These findings offer a new concept that the GS pili belongs to a new class of proteins that can transport electrons through pi-pi interaction between aromatic residues and also provide a valuable tool for guiding further researches of these conductive pili, to investigate their roles in biogeochemical cycling, and potential applications in biomaterials, bioelectronics, and bioenergy.

scholarly journals Theoretical Analyses of Photoinduced Electron Transfer from Aromatic Amino Acids to the Excited Flavins in Some Flavoproteins

10.5772/38078 ◽  
2012 ◽  
Author(s):  
Kiattisak Lugsanangarm ◽  
Nadtanet Nunthaboot ◽  
Somsak Pianwanit ◽  
Sirirat Kokpol ◽  
Fumio Tanak
Keyword(s):  
Amino Acids ◽  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Aromatic Amino Acids ◽  
Theoretical Analyses

scholarly journals Characterization of type IV pili in the life cycle of the predator bacterium Bdellovibrio

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 1040-1051 ◽  
Author(s):  
Khaled K. Mahmoud ◽  
Susan F. Koval
Keyword(s):  
Life Cycle ◽  
Insoluble Fraction ◽  
Type Iv Pili ◽  
Host Cells ◽  
Prey Cell ◽  
Gram Negative ◽  
Type Iv ◽  
Genes Encoding ◽  
Attack Phase

Bdellovibrio and like organisms (BALOs) are obligate prokaryotic predators of other Gram-negative bacteria. Bdellovibrio bacteriovorus is the most studied organism among BALOs. It has a periplasmic life cycle with two major stages: a motile, non-replicative stage spent searching for prey (the attack phase) and a stage spent inside the periplasm of the Gram-negative prey cell (the growth phase) after forming an osmotically stable body termed the bdelloplast. Within Bdellovibrio, there are also strains exhibiting an epibiotic life cycle. The genome sequence of the type strain B. bacteriovorus HD100T revealed the presence of multiple dispersed pil genes encoding type IV pili. Type IV pili in other bacteria are involved in adherence to and invasion of host cells and therefore can be considered to play a role in invasion of prey cells by Bdellovibrio. In this study, genes involved in producing type IV pili were identified in the periplasmic strain B. bacteriovorus 109J and an epibiotic Bdellovibrio sp. strain JSS. The presence of fibres on attack-phase cells was confirmed by examining negative stains of cells fixed with 10 % buffered formalin. Fibres were at the non-flagellated pole on approximately 25 % of attack-phase cells. To confirm that these fibres were type IV pili, a truncated form of PilA lacking the first 35 amino acids was designed to facilitate purification of the protein. The truncated PilA fused to a His-tag was overexpressed in Escherichia coli BL21(DE3) plysS. The fusion protein, accumulated in the insoluble fraction, was purified under denaturing conditions and used to produce polyclonal antisera. Immunoelectron microscopy showed that polar fibres present on the cell surface of the predator were composed of PilA, the major subunit of type IV pili. Immunofluorescence microscopy showed the presence of pilin on attack-phase cells of B. bacteriovorus 109J during attachment to prey cells and just after penetration, inside the bdelloplast. Antibodies against PilA delayed and inhibited predation in co-cultures of Bdellovibrio. This study confirms that type IV pili play a role in invasion of prey cells by Bdellovibrio.

INTRAMOLECULAR EXCITED ENERGY TRANSFER PATHWAYS IN PROTEINS

2008 ◽  
Vol 07 (01) ◽  
pp. 91-102
Author(s):  
LEONARDO R. LAREO ◽  
JANNETH GONZÁLEZ
Keyword(s):  
Amino Acids ◽  
Electron Transfer ◽  
Energy Transfer ◽  
Protein Structure ◽  
Aromatic Amino Acids ◽  
Theoretical Background ◽  
Biological Processes ◽  
Computational Approaches ◽  
Orbital Interactions ◽  
Conducting Materials

The transfer of energy perturbations within protein structure is an important phenomenon in many biological processes. In particular, the transfer of energy perturbations within a molecule in the absence of electron transfer is critical to the understanding of such processes as signaling involving receptors, channels, and enzymes among others, and to the design and development of relevant conducting materials. In this work, we have proposed a mechanism to explain this nonradiative, nonelectron energy transfer based on the π-orbital interactions of aromatic amino acids. Additionally, some theoretical background and possible computational approaches are presented as support for the proposal.

Analysis of type IV pilus and its associated motility in Myxococcus xanthus using an antibody reactive with native pilin and pili

Microbiology ◽  
2005 ◽  
Vol 151 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Yinuo Li ◽  
Renate Lux ◽  
Andrew E. Pelling ◽  
James K. Gimzewski ◽  
Wenyuan Shi
Keyword(s):  
Amino Acids ◽  
Current Model ◽  
Bacterial Species ◽  
Myxococcus Xanthus ◽  
Type Iv Pili ◽  
Gliding Motility ◽  
Soluble Form ◽  
Truncated Form ◽  
Type Iv ◽  
Oligomerization Domain

Myxococcus xanthus possesses a social gliding motility that requires type IV pili (TFP). According to the current model, M. xanthus pili attach to an external substrate and retract, pulling the cell body forward along their long axis. By analogy with the situation in other bacteria employing TFP-dependent motility, M. xanthus pili have been assumed to be composed of pilin (PilA) subunits, but this has not previously been confirmed. The first 28 amino acids of the M. xanthus PilA protein share extensive homology with the N-terminal oligomerization domain of pilins in other bacterial species. To facilitate purification, the authors engineered a truncated form of M. xanthus PilA lacking the first 28 amino acids and purified this protein in soluble form. Polyclonal antibody generated against this protein was reactive with native pilin and pili. Using this antibody, it was confirmed that TFP of M. xanthus are indeed composed of PilA, and that TFP are located unipolarly and required for social gliding motility via retraction. Using tethering as well as motility assays, details of pili function in M. xanthus social motility were further examined.

scholarly journals Expression of Type IV Pili by Moraxella catarrhalis Is Essential for Natural Competence and Is Affected by Iron Limitation

2004 ◽  
Vol 72 (11) ◽  
pp. 6262-6270 ◽  
Author(s):  
Nicole R. Luke ◽  
Amy J. Howlett ◽  
Jianqiang Shao ◽  
Anthony A. Campagnari
Keyword(s):  
Moraxella Catarrhalis ◽  
Pathogenic Bacteria ◽  
Type Iv Pili ◽  
Protein Subunit ◽  
Electron Microscopic ◽  
Type Iv ◽  
Wide Range ◽  
Genes Encoding ◽  
Microscopic Studies

ABSTRACT Type IV pili, filamentous surface appendages primarily composed of a single protein subunit termed pilin, play a crucial role in the initiation of disease by a wide range of pathogenic bacteria. Although previous electron microscopic studies suggested that pili might be present on the surface of Moraxella catarrhalis isolates, detailed molecular and phenotypic analyses of these structures have not been reported to date. We identified and cloned the M. catarrhalis genes encoding PilA, the major pilin subunit, PilQ, the outer membrane secretin through which the pilus filament is extruded, and PilT, the NTPase that mediates pilin disassembly and retraction. To initiate investigation of the role of this surface organelle in pathogenesis, isogenic pilA, pilT, and pilQ mutants were constructed in M. catarrhalis strain 7169. Comparative analyses of the wild-type 7169 strain and three isogenic pil mutants demonstrated that M. catarrhalis expresses type IV pili that are essential for natural genetic transformation. Our studies suggest type IV pilus production by M. catarrhalis is constitutive and ubiquitous, although pilin expression was demonstrated to be iron responsive and Fur regulated. These data indicate that additional studies aimed at elucidating the prevalence and role of type IV pili in the pathogenesis and host response to M. catarrhalis infections are warranted.

scholarly journals Syntrophic interspecies electron transfer drives carbon fixation and growth by Rhodopseudomonas palustris under dark, anoxic conditions

2021 ◽  
Vol 7 (27) ◽  
pp. eabh1852
Author(s):  
Xing Liu ◽  
Lingyan Huang ◽  
Christopher Rensing ◽  
Jie Ye ◽  
Kenneth H. Nealson ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Carbon Fixation ◽  
Rhodopseudomonas Palustris ◽  
Reducing Power ◽  
Extracellular Electron Transfer ◽  
Geobacter Metallireducens ◽  
Electron Transfer Pathway ◽  
Anoxygenic Phototrophs ◽  
Anoxic Environments ◽  
Genes Encoding

In natural anoxic environments, anoxygenic photosynthetic bacteria fix CO2 by photoheterotrophy, photoautotrophy, or syntrophic anaerobic photosynthesis. Here, we describe electroautotrophy, a previously unidentified dark CO2 fixation mode enabled by the electrosyntrophic interaction between Geobacter metallireducens and Rhodopseudomonas palustris. After an electrosyntrophic coculture is formed, electrons are transferred either directly or indirectly (via electron shuttles) from G. metallireducens to R. palustris, thereby providing reducing power and energy for the dark CO2 fixation. Transcriptomic analyses demonstrated the high expression of genes encoding for the extracellular electron transfer pathway in G. metallireducens and the Calvin-Benson-Bassham carbon fixation cycle in R. palustris. Given that sediments constitute one of the most ubiquitous and abundant niches on Earth and that, at depth, most of the sedimentary niche is both anoxic and dark, dark carbon fixation provides a metabolic window for the survival of anoxygenic phototrophs, as well as an as-yet unappreciated contribution to the global carbon cycle.

scholarly journals Receptor recognition by meningococcal type IV pili relies on a specific complex N-glycan

2020 ◽  
Vol 117 (5) ◽  
pp. 2606-2612 ◽  
Author(s):  
Loic Le Guennec ◽  
Zoé Virion ◽  
Haniaa Bouzinba-Ségard ◽  
Catherine Robbe-Masselot ◽  
Renaud Léonard ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Model Organism ◽  
Structural Diversity ◽  
Type Iv Pili ◽  
Type Iv ◽  
Receptor Recognition ◽  
Specific Complex ◽  
Species Specific ◽  
Adhesive Factor ◽  
Antibacterial Target

Bacterial infections are frequently based on the binding of lectin-like adhesins to specific glycan determinants exposed on host cell receptors. These interactions confer species-specific recognition and tropism for particular host tissues and represent attractive antibacterial targets. However, the wide structural diversity of carbohydrates hampers the characterization of specific glycan determinants. Here, we characterized the receptor recognition of type IV pili (Tfp), a key adhesive factor present in numerous bacterial pathogens, using Neisseria meningitidis as a model organism. We found that meningococcal Tfp specifically recognize a triantennary sialylated poly-N-acetyllactosamine–containing N-glycan exposed on the human receptor CD147/Basigin, while fucosylated derivatives of this N-glycan impaired bacterial adhesion. Corroborating the inhibitory role of fucosylation on receptor recognition, adhesion of the meningococcus on nonhuman cells expressing human CD147 required prior defucosylation. These findings reveal the molecular basis of the selective receptor recognition by meningococcal Tfp and thereby, identify a potential antibacterial target.

Sign in / Sign up

Export Citation Format

Share Document