WordNet

hairlike structure especially on the surface of a cell or microorganism
thin projections forming a fringe (especially around the ovarian end of the Fallopian tube)
a giant fungus of the Pacific Northwest; has a very thick stalk and the cortina leaves a ring high up on the stalk
a poisonous fungus with a dry cap and a cortina that does not leave much of a ring on the robust stalk
medlars (同)genus Mespilus

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/28 23:18:04」(JST)

wiki en

Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus. 2- Pilus attaches to recipient cell, brings the two cells together. 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors.

A pilus (Latin for 'hair'; plural : pili) is a hairlike appendage found on the surface of many bacteria.^[1] The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All pili are primarily composed of oligomeric pilin proteins.

Dozens of these structures can exist on the bacteria. Some bacterial viruses or bacteriophages attach to receptors on pili at the start of their reproductive cycle.

Pili are antigenic. They are also fragile and constantly replaced, sometimes with pili of different composition, resulting in altered antigenicity. Specific host responses to old pili structure are not effective on the new structure. Recombination genes of pili code for variable (V) and constant (C) regions of the pili (similar to immunoglobulin diversity).

Types

Conjugative pili

Conjugative pili allow for the transfer of DNA between bacteria, in the process of bacterial conjugation. They are sometimes called "sex pili", in analogy to sexual reproduction, because they allow for the exchange of genes via the formation of "mating pairs". Perhaps the most well-studied is the F pilus of Escherichia coli, encoded by the F plasmid or fertility factor.

A pilus is typically 6 to 7 nm in diameter. During conjugation, a pilus emerging from the donor bacterium ensnares the recipient bacterium, draws it in close, and eventually triggers the formation of a mating bridge, which establishes direct contact and the formation of a controlled pore that allows transfer of DNA from the donor to the recipient. Typically, the DNA transferred consists of the genes required to make and transfer pili (often encoded on a plasmid), and so is a kind of selfish DNA; however, other pieces of DNA are often co-transferred and this can result in dissemination of genetic traits throughout a bacterial population, such as antibiotic resistance. Not all bacteria can make conjugative pili, but conjugation can occur between bacteria of different species.^{[citation needed]}

Type IV pili

Some pili, called type IV pili, generate motile forces.^[2] The external ends of the pili adhere to a solid substrate, either the surface to which the bacteria are attached or to other bacteria, and when the pilus contracts, it pulls the bacteria forward, like a grappling hook. Movement produced by type IV pili is typically jerky, and so it is called twitching motility, as distinct from other forms of bacterial motility, such as motility produced by flagella. However, some bacteria, for example Myxococcus xanthus, exhibit gliding motility. Bacterial type IV pilins are similar in structure to the component flagellins of Archaeal flagella.^[3]

Fimbriae

Attachment of bacteria to host surfaces is required for colonization during infection or to initiate formation of a biofilm. A fimbria is a short pilus that is used to attach the bacterium to a surface. They are sometimes called "attachment pili". Fimbriae are either located at the poles of a cell, or are evenly spread over its entire surface. Mutant bacteria that lack fimbriae cannot adhere to their usual target surfaces and, thus, cannot cause diseases.

Some fimbriae can contain lectins. The lectins are necessary to adhere to target cells because they can recognize oligosaccharide units on the surface of these target cells. Other fimbriae bind to components of the extracellular matrix.

Fimbriae are found in Gram-negative bacteria. In Gram-positive bacteria, the pilin subunits are covalently linked.

Some aerobic bacteria form a thin layer at the surface of a broth culture. This layer, called a pellicle, consists of many aerobic bacteria that adhere to the surface by their fimbriae or "attachment pili". Thus, fimbriae allow the aerobic bacteria to remain on the broth, from which they take nutrients, while they congregate near the air.

References

^ "pilus" at Dorland's Medical Dictionary
^ Mattick JS (2002). "Type IV pili and twitching motility". Annu. Rev. Microbiol. 56 (1): 289–314. doi:10.1146/annurev.micro.56.012302.160938. PMID 12142488.
^ Jarrell; et al. (2009). "Archaeal Flagella and Pili". Pili and Flagella: Current Research and Future Trends. Caister Academic Press. ISBN 978-1-904455-48-6.

External links

Sex Pilus at the US National Library of Medicine Medical Subject Headings (MeSH)
Bacterial Pilus at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. D群レンサ球菌（Streptococcus bovis、Streptococcus equinus complex）による感染症の微生物学、病因、および疫学 microbiology pathogenesis and epidemiology of infections due to group d streptococci streptococcus bovis streptococcus equinus complex
2. コレラ菌感染の病因 pathogenesis of vibrio cholerae infection
3. 髄膜炎菌の微生物学および病理生物学 microbiology and pathobiology of neisseria meningitidis
4. 淋菌感染の疫学および病因 epidemiology and pathogenesis of neisseria gonorrhoeae infection
5. B群レンサ球菌：病原性因子および発症機序 group b streptococcus virulence factors and pathogenic mechanisms

English Journal

A Small Unstructured Region in Vibrio cholerae ToxT Mediates the Response to Positive and Negative Effectors and ToxT Proteolysis.

Thomson JJ1, Plecha SC1, Withey JH2.
Journal of bacteriology.J Bacteriol.2015 Feb 1;197(3):654-68. doi: 10.1128/JB.02068-14. Epub 2014 Nov 24.
Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. The production of the virulence factors that are required for human disease is controlled by a complex network of transcriptional and posttranscriptional regulators. ToxT is the transcription regulator that directly cont
PMID 25422303

Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds.

Pöritz M1, Schiffmann CL2, Hause G3, Heinemann U1, Seifert J2, Jehmlich N2, von Bergen M4, Nijenhuis I5, Lechner U6.
Applied and environmental microbiology.Appl Environ Microbiol.2015 Jan 15;81(2):587-96. doi: 10.1128/AEM.02597-14. Epub 2014 Nov 7.
Polyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments. Dehalococcoides mccartyi strain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds
PMID 25381236

Pilin Processing Follows a Different Temporal Route than That of Archaellins in Methanococcus maripaludis.

Nair DB1, Jarrell KF2.
Life (Basel, Switzerland).Life (Basel).2015 Jan 5;5(1):85-101.
Methanococcus maripaludis has two different surface appendages: type IV-like pili and archaella. Both structures are believed to be assembled using a bacterial type IV pilus mechanism. Each structure is composed of multiple subunits, either pilins or archaellins. Both pilins and archaellins are made
PMID 25569238

Japanese Journal

29aPS-47 線毛を持つ桿状バクテリアのTwitching運動と粘性抵抗(29aPS 領域12ポスターセッション,領域12(ソフトマター物理,化学物理,生物物理))

森河良太,宮川毅,高須昌子
日本物理学会講演概要集 68(1-2), 457, 2013-03-26
NAID 110009644079

Involvement of Flagella-Driven Motility and Pili in Pseudomonas aeruginosa Colonization at the Air-Liquid Interface

YAMAMOTO KYOSUKE,ARAI HIROYUKI,ISHII MASAHARU [他],IGARASHI YASUO
Microbes and environments 27(3), 320-323, 2012-09-01
… A pili-deficient mutant showed normal pellicle formation properties, while the disruption of the pilus gene in the flagella-deficient mutant restored normal pellicle morphology. …
NAID 10030869709

In Silico Analyses of Primers Used to Detect the Pathogenicity Genes of Vibrio cholerae

GARDES JULIEN,CROCE OLIVIER,CHRISTEN RICHARD
Microbes and environments 27(3), 250-256, 2012-09-01
… In Vibrio cholerae, the etiological agent of cholera, most of the virulence genes are located in two pathogenicity islands, named TCP (Toxin-Co-regulated Pilus) and CTX (Cholera ToXins). …
NAID 10030869228