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The ‘P‐usher’, a novel protein transporter involved in fimbrial assembly and TpsA secretion
Author(s) -
Ruer Ségolène,
Ball Geneviève,
Filloux Alain,
de Bentzmann Sophie
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.197
Subject(s) - biology , secretion , transporter , transport protein , microbiology and biotechnology , genetics , endocrinology , gene
We identified a new bacterial transporter, the Pseudomonas aeruginosa CupB3 protein, which is an outer membrane usher involved in pili assembly. In CupB3, the usher domain has fused during evolution with a POTRA ( po lypeptide‐ tr ansport‐ a ssociated)‐like domain found in TpsB transporters of two‐partner secretion systems. In TpsBs, the POTRA captures the TpsA passenger, which is then transported across the outer membrane through the TpsB β‐barrel. We named CupB3 a ‘P‐usher’ for P OTRA‐like domain‐containing usher . We showed that CupB3 assembles CupB1 fimbrial subunits into pili and secretes CupB5, a TpsA‐like protein. The CupB3 usher domain has the function of a TpsB β‐barrel in CupB5 translocation. We revealed that the POTRA‐like domain is neither essential for CupB1 fimbriae assembly nor for cell surface exposition of CupB5, but is crucial to coordinate bona fide transport of CupB1 and CupB5 through the usher domain. The P‐usher defines a novel transport pathway involving a molecular machine made with old spare parts.