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0  structures 527  species 0  interactions 534  sequences 2  architectures

Family: CsgF (PF10614)

Summary: Type VIII secretion system (T8SS), CsgF protein

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Type VIII secretion system (T8SS), CsgF protein Provide feedback

The extracellular nucleation-precipitation (ENP) pathway or Type VIII secretion system (T8SS) in Gram-negative (diderm) bacteria is responsible for the secretion and assembly of prepilins for fimbiae biogenesis, the prototypical curli. Besides the T2SS that can be involved in the assembly of prototypical Type 4 pilus, the T4SS that can be involved in the biogenesis of the prototypical pilus T, the T3SS involved in the assembly of the injectisome and the T7SS involved in the formation of the prototypical Type 1 pilus, the T8SS differs in that fibre-growth occurs extracellularly. The curli, also called thin aggregative fimbriae (Tafi), are the only fimbriae dependent on the T8SS. Tafi were first identified in Salmonella spp and the controlling operon termed agf; however subsequent isolation of the homologous operon in E coli led to its being called csg. In the absence of extracellular polysaccharides Tafi appear curled, although when expressed with such polysaccharides their morphology appears as a tangled amorphous matrix [2]. CsgF is one of three putative curli assembly factors appearing to act as a nucleator protein. Unlike eukaryotic amyloid formation, curli biogenesis is a productive pathway requiring a specific assembly machinery [1].

Literature references

  1. Chapman MR, Robinson LS, Pinkner JS, Roth R, Heuser J, Hammar M, Normark S, Hultgren SJ; , Science. 2002;295:851-855.: Role of Escherichia coli curli operons in directing amyloid fiber formation. PUBMED:11823641 EPMC:11823641

  2. Gibson DL, White AP, Rajotte CM, Kay WW; , Microbiology. 2007;153:1131-1140.: AgfC and AgfE facilitate extracellular thin aggregative fimbriae synthesis in Salmonella enteritidis. PUBMED:17379722 EPMC:17379722

  3. Desvaux M, Parham NJ, Scott-Tucker A, Henderson IR;, Trends Microbiol. 2004;12:306-309.: The general secretory pathway: a general misnomer?. PUBMED:15223057 EPMC:15223057

  4. Peabody CR, Chung YJ, Yen MR, Vidal-Ingigliardi D, Pugsley AP, Saier MH Jr;, Microbiology. 2003;149:3051-3072.: Type II protein secretion and its relationship to bacterial type IV pili and archaeal flagella. PUBMED:14600218 EPMC:14600218

  5. Desvaux M, Hebraud M, Talon R, Henderson IR;, Trends Microbiol. 2009;17:139-145.: Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue. PUBMED:19299134 EPMC:19299134


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR018893

The extracellular nucleation-precipitation (ENP) pathway or Type VIII secretion system (T8SS) in Gram-negative (diderm) bacteria is responsible for the secretion and assembly of prepilins for fimbiae biogenesis, the prototypical curli. Besides the T2SS that can be involved in the assembly of prototypical Type 4 pilus, the T4SS that can be involved in the biogenesis of the prototypical pilus T, the T3SS involved in the assembly of the injectisome and the T7SS involved in the formation of the prototypical Type 1 pilus, the T8SS differs in that fibre-growth occurs extracellularly. The curli, also called thin aggregative fimbriae (Tafi), are the only fimbriae dependent on the T8SS. Tafi were first identified in Salmonella spp and the controlling operon termed agf; however subsequent isolation of the homologous operon in E coli led to its being called csg. In the absence of extracellular polysaccharides Tafi appear curled, although when expressed with such polysaccharides their morphology appears as a tangled amorphous matrix [PUBMED:17379722]. CsgF is one of three putative curli assembly factors appearing to act as a nucleator protein. Unlike eukaryotic amyloid formation, curli biogenesis is a productive pathway requiring a specific assembly machinery [PUBMED:11823641].

Domain organisation

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Alignments

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Representative proteomes NCBI
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Meta
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  Seed
(6)
Full
(534)
Representative proteomes NCBI
(165)
Meta
(266)
RP15
(12)
RP35
(22)
RP55
(37)
RP75
(56)
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  Seed
(6)
Full
(534)
Representative proteomes NCBI
(165)
Meta
(266)
RP15
(12)
RP35
(22)
RP55
(37)
RP75
(56)
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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

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Curation and family details

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Curation View help on the curation process

Seed source: FIG077109 (Release 2.0)
Previous IDs: Tafi-CsgF;
Type: Family
Author: FIGFAMs, Mistry J, Coggill P, Desvaux M
Number in seed: 6
Number in full: 534
Average length of the domain: 127.60 aa
Average identity of full alignment: 69 %
Average coverage of the sequence by the domain: 95.73 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 29.7 29.6
Noise cut-off 24.3 18.9
Model length: 142
Family (HMM) version: 4
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