Protein Family Models

In Gram-negative bacteria the biogenesis of fimbriae (or pili) requires a two- component assembly and transport system which is composed of a periplasmic chaperone and an outer membrane protein which has been termed a molecular 'usher' [1-3]. The usher protein is rather large (from 86 to 100 Kd) and seems to be mainly composed of membrane-spanning beta-sheets, a structure reminiscent of porins. 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 cysteines, the first one located in the N-terminal part and the second at the C-terminal extremity that are probably involved in disulphide bonds. The best conserved region is located in the central part of these proteins [4-5]. [1]. 7909802. Chaperone-assisted self-assembly of pili independent of cellular energy. Jacob-Dubuisson F, Striker R, Hultgren SJ;. J Biol Chem. 1994;269:12447-12455. [2]. 7906265. Permissive linker insertion sites in the outer membrane protein of 987P fimbriae of Escherichia coli. Schifferli DM, Alrutz MA;. J Bacteriol. 1994;176:1099-1110. [3]. 7906046. Structural and evolutionary relationships between two families of bacterial extracytoplasmic chaperone proteins which function cooperatively in fimbrial assembly. Van Rosmalen M, Saier MH Jr;. Res Microbiol. 1993;144:507-527. [4]. 19380723. Insights into pilus assembly and secretion from the structure and functional characterization of usher PapC. Huang Y, Smith BS, Chen LX, Baxter RH, Deisenhofer J;. Proc Natl Acad Sci U S A. 2009;106:7403-7407. [5]. 18485872. Fiber formation across the bacterial. TRUNCATED at 1650 bytes (from Pfam)

Date:

2024-10-16

fimbria/pilus outer membrane usher family protein that may be involved in the export and/or assembly of fimbrial subunits across the outer membrane

Date:

2024-05-23