Pili and Hosts
Paul Pumpens in Single-Stranded RNA Phages, 2020
A pilus (Latin for hair; plural: pili). According to the current Medical Subject Headings (MeSH) definition at the appropriate NLM page (https://meshb.nlm.nih.gov/record/ui?name=Sex%20Pilus):pili, sex, are filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. (Singleton P, Sainsbury D: Dictionary of Microbiology and Molecular Biology, 2nd ed. p. 675. 1993. Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with permission.)
Bacteria
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Pili are very small or fine filamentous appendages that extend outward from some bacteria. They, like flagella, originate in a basal body in the cytoplasmic membrane. Pili occur most frequently on Gram-negative bacilli. They are of two types: (A) the sex pilus that is involved in conjugation and allows passage of DNA through the pilus into another bacterial cell, and (B) an attachment pilus that allows bacteria to attach to host cells, especially mucosal cells. Attachment is often necessary for a pathogen to achieve colonization of a host tissue and initiate a disease process. For example, pili of Neisseria gonorrheae serve to attach the organism to the urethral mucosa and are an important factor in the organisms′ virulence. Vaccines using pilus protein as antigen are being developed for several diseases including gonorrhea and various types of bacterial dysentery.
Pseudomonas
Dongyou Liu in Handbook of Foodborne Diseases, 2018
Type III secretion system is a needle-like appendage that forms pores in the eukaryotic membrane and allows the injection of toxins directly, a mechanism used by pathogens like Salmonella, Shigella, and Pseudomonas species to infect the host. This pilus-like structure allows the translocation of effectors such as Exo S, Exo T, Exo Y, and Exo U from bacteria into the host.7,109 Exo S is a cytotoxin with two active domains, a C-terminal ADP-ribosyltransferase domain and an n-terminal Rho GTPase–activating proteins (GAP) domain, that disrupt the normal cytoskeletal organization as well as are capable of modulating host immune and inflammatory response, respectively.110 Exo T is similar to Exo S with dual active domain and has similar effect on cytoskeleton as well as inhibits wound repair in the host. Exo Y is an adenylate cyclase that increases cytosolic cAMP that leads to increased pulmonary microvascular intercellular formation and lung permeability, thus helping in colonization inside the host. Exo U is a potent eukaryotic cell membrane disruptor and a major cytotoxin. It is mainly responsible for the decompartmentalization in acute lung injury model that leads to sepsis.84,111,112
High throughput and targeted screens for prepilin peptidase inhibitors do not identify common inhibitors of eukaryotic gamma-secretase
Published in Expert Opinion on Drug Discovery, 2023
Pradip Kumar Singh, Michael S. Donnenberg
Type 4 pili (T4P) are retractile filamentous surface appendages present in numerous Gram-positive and Gram-negative bacteria as well as archaea [1–3]. T4P have many functions, including twitching motility, surface attachment, DNA uptake, biofilm formation, host colonization, auto-aggregation, and environmental sensing. In several bacterial pathogens, such as enteropathogenic Escherichia coli (EPEC), Vibrio cholerae, Pseudomonas aeruginosa, Neisseria meningitidis, N. gonorrhoeae, and Clostridioides difficile, T4P may play a role in pathogenesis [4,5]. The T4P of EPEC and V. cholerae are proven virulence factors in experimental human infection [6,7]. The filament of T4P is composed of pilin proteins in a helical array, and its biogenesis requires a complex multi-protein machine that spans the cytoplasmic membrane and, in Gram-negative bacteria, the outer membrane [8]. Pilin protein is synthesized as a prepilin, which has a class III N-terminal signal peptide sequence. Cleavage of this signal sequence is required before the pilin can be incorporated into the growing pilus [9–11]. A dedicated prepilin peptidase (PPP) cleaves the leader sequence of the prepilin and, in many cases, methylates the nascent N-terminal residue [12–14]. Deletion or active-site mutations in PPP genes preclude T4P expression [11,13,15,16].
The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies
Published in Gut Microbes, 2022
Frida Gorreja, W. Allan Walker
In another study, a novel probiotic mechanism involving mucus-binding peptides of LGG was shown to outcompete Enterococcus faecium colonization.90 Vancomycin-resistant enterococci peptides with known pathogenic properties were shown to share sequences with the peptides of SPCA-SRIP1 pili of the probiotic LGG.90 Hence, immunological and functional similarities between LGG and the pathogen E. faecium strain E1165 opens new frontiers for prophylaxis and treatment of vancomycin-resistant enterococcus infections.90 Supplementation of another L. rhamnosus, Lacticaseibacillus rhamnosus 19,070–2, to infants with intestinal colic was found to decrease crying and fuss time.169 These benefits may be due to the fact that probiotic bacterial pili can better adhere, colonize (Box 1) and exclude gas-forming Clostridioides (previously Clostridium) difficile, Klebsiella pneumoniae, and Escherichia which are increased in colic.169,170
Interleukin-1β secretion induced by mucosa-associated gut commensal bacteria promotes intestinal barrier repair
Published in Gut Microbes, 2022
Wan-Jung H. Wu, Myunghoo Kim, Lin-Chun Chang, Adrien Assie, Fatima B. Saldana-Morales, Daniel F. Zegarra-Ruiz, Kendra Norwood, Buck S. Samuel, Gretchen E. Diehl
To further characterize the E. coli, we selected one isolate for genomic sequencing. The complete genome of the B1 phylotype, mouse derived E. coli isolate GDAR2-2 was sequenced using PacBio and assembled de novo into two fully closed contigs. This consisted of the bacterial genome of 4,928,781 base pairs (bp) in length with a 50.73% GC content. We also identified an associated 71,810 bp IncF low copy number plasmid with 94 predicted coding genes with mostly hypothetical functions. Sequence annotations of the genome predicted 4841 coding sequences (Figure S1a) including the presence of genes commonly found associated with commensal E. coli. We also found adhesion genes for long polar fimbriae and pilus assembly proteins.
Related Knowledge Centers
- Archaea
- Bacteria
- Bacterial Conjugation
- Bacteriophage
- Fibrous Protein
- Oligomer
- Pilin
- Virus
- Receptor
- Reproduction