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Bacteria
Published in Julius P. Kreier, 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.
Neuroinfectious Diseases
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Jeremy D. Young, Jesica A. Herrick, Scott Borgetti
Most bacterial pathogens implicated in community-associated meningitis begin with nasopharyngeal (NP)colonization of the host. Bacterial pili are involved in adherence of certain organisms to the NP epithelial cells, such as with N. meningitis and H. influenzae.
Basic Microbiology
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Unlike eukaryotic cells, bacteria can transfer DNA sequences between individuals that are not of the same lineage. This can occur between members of the same species or between different species. The three main mechanisms that bacteria use to perform horizontal gene transfer are listed here. Transformation—DNA found within the extracellular environment of the bacteria is actively taken up into the bacteria and is used either in its native state, such as with plasmids, or incorporated into the genome, as with chromosomal DNA sequences. The utilization of these sequences can often confer drastic new phenotypes on the bacteria that harbor those sequences.Transduction—Viruses that are present, incorporated into the chromosome of a bacterium, exit the infected bacteria to infect new host cells. In the process, they remove small portions of the chromosome of the infected bacteria. In the new host, these sequences are integrated into the new host genome.Conjugation—As mentioned previously, bacteria that are able to conjugate by producing sex pili can transfer DNA sequences across the pili and lead to incorporation of new chromosomal sequences within the other mating bacteria.
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].
Experimental and investigational drugs for the treatment of acute otitis media
Published in Expert Opinion on Investigational Drugs, 2019
Nicola Principi, Susanna Esposito
Although all otopathogens can be associated with biofilm production and recurrent AOM, ntHi is the most important in this regard [26]. To eliminate biofilm and improve antibiotic efficacy or favour spontaneous AOM resolution, a vaccine against the majority subunit of ntHi type IV pili, pilA, was considered as a potential solution. This is because pilA is essential for ntHi virulence and biofilm formation [27]. Antibodies against this component were able to disrupt and prevent the formation of ntHI biofilms in vitro [28,29] and to solve ntHI-induced AOM in animal models [30]. Moreover, it has recently been shown that these antibodies against pilA could also inhibit formation of Mc biofilm formation, suggesting a potential positive effect in the case of ntHi and Mc combined aetiology of AOM [31]. As previously mentioned, this attractive measure is presently limited to the experimental animals for which the use of this vaccine has also been considered for prevention of rAOM.
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.