The DraC usher in Dr fimbriae biogenesis of uropathogenic E. coli Dr + strains
- PDF / 1,217,780 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 46 Downloads / 153 Views
ORIGINAL PAPER
The DraC usher in Dr fimbriae biogenesis of uropathogenic E. coli Dr+ strains Beata Zalewska-Pia˛tek • Marta Kur • Sabina Wilkanowicz • Rafał Pia˛tek • Jo´zef Kur
Received: 13 August 2009 / Revised: 12 February 2010 / Accepted: 10 March 2010 / Published online: 28 March 2010 Ó Springer-Verlag 2010
Abstract Biogenesis of Dr fimbriae encoded by the dra gene cluster of uropathogenic Escherichia coli strains requires the chaperone-usher pathway. This secretion system is based on two non-structural assembly components, the DraB periplasmic chaperone and DraC outer-membrane usher. The DraB controls the folding of DraE subunits, and DraC forms the assembly and secretion platform for polymerization of subunits in linear fibers. In this study, mutagenesis of the DraC N-terminus was undertaken to select residues critical for Dr fimbriae bioassembly. The DraC-F4A, DraC-C64, DraC-C100A and DraC-W142A significantly reduced the adhesive ability of E. coli strains. The biological activity of the DraC mutants as a assembly platform for Dr fimbriae polymerization was verified by agglutination of human erythrocytes and adhesion to DAF localized at the surface of CHO-DAF? and HeLa cells. The residue F4 of the DraC usher conserved among FGL and FGS chaperone-assembled adhesive organelles can be used to design pillicides blocking the biogenesis of Dr fimbriae. Because the draC and afaC-III genes share 100% identity the range of the virulence determinant inhibitors could also be extended to E. coli strains encoding afa-3 gene cluster. The investigations performed showed that the usher Nterminus plays an important role in biogenesis of complete fiber.
Communicated by Jorge Membrillo-Herna´ndez. B. Zalewska-Pia˛tek (&) M. Kur S. Wilkanowicz R. Pia˛tek J. Kur Department of Microbiology, Gdan´sk University of Technology, ul. G. Narutowicza 11/12, 80-952 Gdan´sk, Poland e-mail: [email protected]
Keywords Uropathogenic Escherichia coli dra gene cluster DraC usher Dr fimbriae
Introduction Gram-negative bacteria use the highly conserved chaperone-usher pathway to secrete proteins across their outer membrane (OM) for the formation of different adhesive organelles such as adhesive pili or fimbriae (rod-like elements of 5–7 nm in diameter). Based on the sequence analysis, two families of the periplasmic chaperones have been identified, FGS (F1-G1 short) with a short loop (10– 20 residues) connecting F1 and G1 b-strands and FGL (F1G1 long) with a long and flexible loop (21–29 residues) between F1 and G1 b-strands (Saulino et al. 2000; Zavialov et al. 2007). The FGL chaperone-assembled organelles, fimbrial polyadhesins, consist of linear polymers of one or two types of protein subunits. The FGS-assembled organelles, adhesive pili, are composite structures built from multiple pilus subunits. Molecular ushers form a conserved family of proteins (Fimbrial Usher Proteins, FUP) without any specific differences in sequences involved in the assembly of fimbrial polyadhesins or adhesive pili (Capitani et al. 2006a, b; Nis
Data Loading...
