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Microbiology Spectrum Mar 2019Type IV pilus (T4P)-like systems have been identified in almost every major phylum of prokaryotic life. They include the type IVa pilus (T4aP), type II secretion system... (Review)
Review
Type IV pilus (T4P)-like systems have been identified in almost every major phylum of prokaryotic life. They include the type IVa pilus (T4aP), type II secretion system (T2SS), type IVb pilus (T4bP), Tad/Flp pilus, Com pilus, and archaeal flagellum (archaellum). These systems are used for adhesion, natural competence, phage adsorption, folded-protein secretion, surface sensing, swimming motility, and twitching motility. The T4aP allows for all of these functions except swimming and is therefore a good model system for understanding T4P-like systems. Recent structural analyses have revolutionized our understanding of how the T4aP machinery assembles and functions. Here we review the structure and function of the T4aP.
Topics: Fimbriae Proteins; Fimbriae, Bacterial; Flagella; Protein Transport; Type II Secretion Systems
PubMed: 30825300
DOI: 10.1128/microbiolspec.PSIB-0006-2018 -
Current Topics in Microbiology and... 2017Pili of Gram-positive bacteria are unique structures on the bacterial surface, assembled from covalently linked polypeptide subunits. Pilus assembly proceeds by... (Review)
Review
Pili of Gram-positive bacteria are unique structures on the bacterial surface, assembled from covalently linked polypeptide subunits. Pilus assembly proceeds by transpeptidation reactions catalyzed by sortases, followed by covalent anchoring of the filament in the peptidoglycan layer. Another distinctive property is the presence of intramolecular isopeptide bonds, conferring extraordinary chemical and mechanical stability to these elongated structures. Besides their function in cell adhesion and biofilm formation, this section discusses possible application of pilus constituents as vaccine components against Gram-positive pathogens.
Topics: Bacterial Adhesion; Bacterial Vaccines; Biofilms; Fimbriae, Bacterial; Gram-Positive Bacteria
PubMed: 26847355
DOI: 10.1007/82_2015_5016 -
International Journal of Molecular... Nov 2021The endospores (spores) of many sensu lato species are decorated with multiple hair/pilus-like appendages. Although they have been observed for more than 50 years, all... (Review)
Review
The endospores (spores) of many sensu lato species are decorated with multiple hair/pilus-like appendages. Although they have been observed for more than 50 years, all efforts to characterize these fibers in detail have failed until now, largely due to their extraordinary resilience to proteolytic digestion and chemical solubilization. A recent structural analysis of endospore appendages (Enas) using cryo-electron microscopy has revealed the structure of two distinct fiber morphologies: the longer and more abundant "Staggered-type" (S-Ena) and the shorter "Ladder-like" type (L-Ena), which further enabled the identification of the genes encoding the S-Ena. Ena homologs are widely and uniquely distributed among sensu lato species, suggesting that appendages play important functional roles in these species. The discovery of genes is expected to facilitate functional studies involving Ena-depleted mutant spores to explore the role of Enas in the interaction between spores and their environment. Given the importance of spores for the food industry and in medicine, there is a need for a better understanding of their biological functions and physicochemical properties. In this review, we discuss the current understanding of the Ena structure and the potential roles these remarkable fibers may play in the adhesion of spores to biotic and abiotic surfaces, aggregation, and biofilm formation.
Topics: Bacillus cereus; Bacterial Proteins; Binding Sites; Biofilms; Cryoelectron Microscopy; Fimbriae, Bacterial; Gene Expression Regulation, Bacterial; Models, Molecular; Protein Binding; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Spores, Bacterial
PubMed: 34830248
DOI: 10.3390/ijms222212367 -
Journal of Industrial Microbiology &... Oct 2020Type IV pili (T4P) are bacterial appendages used for cell adhesion and surface motility. In metal-reducing bacteria in the genus Geobacter, they have the unique property... (Review)
Review
Type IV pili (T4P) are bacterial appendages used for cell adhesion and surface motility. In metal-reducing bacteria in the genus Geobacter, they have the unique property of being conductive and essential to wire cells to extracellular electron acceptors and other cells within biofilms. These electroactive bacteria use a conserved pathway for biological assembly and disassembly of a short and aromatic dense peptide subunit (pilin). The polymerization of the pilins clusters aromatic residues optimally for charge transport and exposes ligands for metal immobilization and reduction. The simple design yet unique functionalities of conductive T4P afford opportunities for the scaled-up production of recombinant pilins and their in vitro assembly into electronic biomaterials of biotechnological interest. This review summarizes current knowledge of conductive T4P biogenesis and functions critical to actualize applications in bioelectronics, bioremediation, and nanotechnology.
Topics: Biofilms; Biology; Biotechnology; Electric Conductivity; Fimbriae Proteins; Fimbriae, Bacterial; Geobacter; Metals; Nanowires; Peptides
PubMed: 33009965
DOI: 10.1007/s10295-020-02312-5 -
Current Opinion in Microbiology Apr 2016Type IV pili, a special class of bacterial surface filaments, are key behavioral mediators for many important human pathogens. However, we know very little about the... (Review)
Review
Type IV pili, a special class of bacterial surface filaments, are key behavioral mediators for many important human pathogens. However, we know very little about the role of these structures in the lifestyles of plant-associated bacteria. Over the past few years, several groups studying the extensive genus of Xanthomonas spp. have gained insights into the roles of played by type IV pili in bacteria-host interactions and pathogenesis, motility, biofilm formation, and interactions with bacteriophages. Protein-protein interaction studies have identified T4P regulators and these, along with structural studies, have begun to reveal some of the possible molecular mechanisms that may control the extension/retraction cycles of these dynamic filaments.
Topics: Bacterial Proteins; Fimbriae, Bacterial; Gene Expression Regulation, Bacterial; Xanthomonas
PubMed: 26874963
DOI: 10.1016/j.mib.2016.01.007 -
Nature Reviews. Microbiology May 2017Pili are crucial virulence factors for many Gram-negative pathogens. These surface structures provide bacteria with a link to their external environments by enabling... (Review)
Review
Pili are crucial virulence factors for many Gram-negative pathogens. These surface structures provide bacteria with a link to their external environments by enabling them to interact with, and attach to, host cells, other surfaces or each other, or by providing a conduit for secretion. Recent high-resolution structures of pilus filaments and the machineries that produce them, namely chaperone-usher pili, type IV pili, conjugative type IV secretion pili and type V pili, are beginning to explain some of the intriguing biological properties that pili exhibit, such as the ability of chaperone-usher pili and type IV pili to stretch in response to external forces. By contrast, conjugative pili provide a conduit for the exchange of genetic information, and recent high-resolution structures have revealed an integral association between the pilin subunit and a phospholipid molecule, which may facilitate DNA transport. In addition, progress in the area of cryo-electron tomography has provided a glimpse of the overall architecture of the type IV pilus machinery. In this Review, we examine recent advances in our structural understanding of various Gram-negative pilus systems and discuss their functional implications.
Topics: Bacterial Adhesion; Conjugation, Genetic; Fimbriae Proteins; Fimbriae, Bacterial; Gram-Negative Bacteria; Virulence Factors
PubMed: 28496159
DOI: 10.1038/nrmicro.2017.40 -
Microbiology and Molecular Biology... Sep 2022Type IV pili (T4P) are retractable multifunctional nanofibers present on the surface of numerous bacterial and archaeal species. Their importance to microbiology is... (Review)
Review
Type IV pili (T4P) are retractable multifunctional nanofibers present on the surface of numerous bacterial and archaeal species. Their importance to microbiology is difficult to overstate. The scientific journey leading to our current understanding of T4P structure and function has included many innovative research milestones. Although multiple T4P reviews over the years have emphasized recent advances, we find that current reports often omit many of the landmark discoveries in this field. Here, we attempt to highlight chronologically the most important work on T4P, from the discovery of pili to the application of sophisticated contemporary methods, which has brought us to our current state of knowledge. As there remains much to learn about the complex machine that assembles and retracts T4P, we hope that this review will increase the interest of current researchers and inspire innovative progress.
Topics: Archaea; Bacteria; Fimbriae, Bacterial
PubMed: 35612326
DOI: 10.1128/mmbr.00076-22 -
Cellular Microbiology Apr 2020Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for two devastating forms of invasive diseases: purpura fulminans and meningitis.... (Review)
Review
Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for two devastating forms of invasive diseases: purpura fulminans and meningitis. Interaction with both peripheral and cerebral microvascular endothelial cells is at the heart of meningococcal pathogenesis. During the last two decades, an essential role for meningococcal type IV pili in vascular colonisation and disease progression has been unravelled. This review summarises 20 years of research on meningococcal type IV pilus-dependent virulence mechanisms, up to the identification of promising anti-virulence compounds that target type IV pili.
Topics: Animals; Bacterial Adhesion; Endothelial Cells; Fimbriae, Bacterial; Humans; Meningococcal Infections; Mice; Neisseria meningitidis; Virulence
PubMed: 32185901
DOI: 10.1111/cmi.13185 -
Molecular Microbiology Dec 2019In the diverse world of bacterial pili, type IV pili (Tfp) are unique for two reasons: their multifunctionality and ubiquity. This latter feature offers an extraordinary... (Review)
Review
In the diverse world of bacterial pili, type IV pili (Tfp) are unique for two reasons: their multifunctionality and ubiquity. This latter feature offers an extraordinary possibility, that is, to perform comparative studies in evolutionarily distant species in order to improve our fragmentary understanding of Tfp biology. Regrettably, such potential has remained largely untapped, because, for 20 years, Tfp have only been characterised in diderm bacteria. However, recent studies of Tfp in monoderms have started closing the gap, revealing many interesting commonalities and a few significant differences, extending the frontiers of knowledge of Tfp biology. Here, I review the current state of the art of the Tfp field in monoderm bacteria and discuss resulting implications for our general understanding of the assembly and function of these widespread filamentous nanomachines.
Topics: Bacteria; Bacterial Proteins; Clostridiales; Fimbriae Proteins; Fimbriae, Bacterial; Gram-Positive Bacteria; Membrane Proteins; Streptococcus; Streptococcus sanguis
PubMed: 31556183
DOI: 10.1111/mmi.14397 -
Current Opinion in Structural Biology Aug 2012Pili belong to a broad class of bacterial surface structures that play a key role in infection and pathogenicity. The largest and best characterised pilus biogenesis... (Review)
Review
Pili belong to a broad class of bacterial surface structures that play a key role in infection and pathogenicity. The largest and best characterised pilus biogenesis system--the chaperone-usher pathway--is particularly remarkable in its ability to synthesise and display highly organised structures at the outer membrane without any input from endogenous energy sources. The past few years have heralded exciting new developments in our understanding of the structural biology and mechanism of pilus assembly, which are discussed in this review. Such knowledge will be particularly important in the future, as we approach an era of widespread resistance to common antibiotics and require new targets.
Topics: Fimbriae Proteins; Fimbriae, Bacterial; Gram-Negative Bacteria; Kinetics; Models, Molecular; Molecular Chaperones; Protein Conformation; Protein Multimerization
PubMed: 22402496
DOI: 10.1016/j.sbi.2012.02.001