Fimbrial Usher protein
Structure of the type 1 pilus assembly platform FimD(25-139).[1]
Identifiers
SymbolUsher
PfamPF00577
InterProIPR000015
PROSITEPDOC00886
TCDB1.B.11
OPM superfamily187
OPM protein4j3o
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

The fimbrial usher protein is involved in biogenesis of the pilus in Gram-negative bacteria. The biogenesis of some fimbriae (or pili) requires a two-component assembly and transport system which is composed of a periplasmic chaperone and a pore-forming outer membrane protein which has been termed a molecular 'usher'; this is the chaperone-usher pathway.[2][3][4]

The usher protein has a molecular weight ranging from 86 to 100 kDa and is composed of a membrane-spanning 24-stranded beta barrel domain, reminiscent of porins, and of four periplasmic soluble domains: an N-terminal one of about 120 residues (NTD),[1] a 'middle' domain of about 80 residues[5] located as a soluble insertion within the beta barrel region of the sequence (plug domain) and two IG-like domains (each about 80 residues long) at the C-terminus (CTD1 and CTD2).[6] Although the degree of sequence similarity of these proteins is not very high they share a number of characteristics. One of these is the presence of two pairs of disulfide bond-forming cysteines, the first one located in the NTD and the second in CTD2. The best conserved region of the sequence corresponds to the plug domain.

References

  1. 1 2 Nishiyama M, Horst R, Eidam O, et al. (June 2005). "Structural basis of chaperone–subunit complex recognition by the type 1 pilus assembly platform FimD". EMBO J. 24 (12): 2075–86. doi:10.1038/sj.emboj.7600693. PMC 1150887. PMID 15920478.
  2. ↑ Hultgren SJ, Jacob-Dubuisson F, Striker R (1994). "Chaperone-assisted self-assembly of pili independent of cellular energy". J. Biol. Chem. 269 (17): 12447–12455. doi:10.1016/S0021-9258(18)99895-9. PMID 7909802.
  3. ↑ Schifferli DM, Alrutz MA (1994). "Permissive linker insertion sites in the outer membrane protein of 987P fimbriae of Escherichia coli". J. Bacteriol. 176 (4): 1099–1110. doi:10.1128/JB.176.4.1099-1110.1994. PMC 205162. PMID 7906265.
  4. ↑ Saier Jr MH, Van Rosmalen M (1993). "Structural and evolutionary relationships between two families of bacterial extracytoplasmic chaperone proteins which function cooperatively in fimbrial assembly". Res. Microbiol. 144 (7): 507–527. doi:10.1016/0923-2508(93)90001-I. PMID 7906046.
  5. ↑ Capitani G, Eidam O, Grütter MG (2006). "Evidence for a novel domain of bacterial outer membrane ushers". Proteins. 65 (4): 816–23. doi:10.1002/prot.21147. PMID 17066380. S2CID 28766740.
  6. ↑ Phan G, Remaut H, Wang T, Allen WJ, Pirker KF, Lebedev A, et al. (2011). "Crystal structure of the FimD usher bound to its cognate FimC-FimH substrate". Nature. 474 (7349): 49–53. doi:10.1038/nature10109. PMC 3162478. PMID 21637253.
This article incorporates text from the public domain Pfam and InterPro: IPR000015
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