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PcrH of Pseudomonas aeruginosa is essential for secretion and assembly of the type III translocon
Umeå University, Faculty of Medicine, Molecular Biology.
Umeå University, Faculty of Medicine, Molecular Biology.
Umeå University, Faculty of Medicine, Molecular Biology.
2003 (English)In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 188, no 12, 1909-1921 p.Article in journal (Refereed) Published
Abstract [en]

Pseudomonas aeruginosa harbors a type III secretion system that translocates antihost effectors into an infected eukaryotic cell. PcrH is a key component of type III secretion in this essential virulence strategy. In the absence of PcrH, P. aeruginosa is translocation deficient because of a specific reduction in presecretory stability and subsequent secretion of PopB and PopD, 2 proteins essential for the translocation process. PcrH exerts this chaperone function by binding directly to PopB and PopD. Consistent with the genetic relatedness of PcrH with LcrH of pathogenic Yersinia species, these proteins are functionally interchangeable with respect to their ability to complement the translocation defect associated with either a lcrH or pcrH null mutant, respectively. Thus, the translocator class of chaperones performs a critical function in ensuring the assembly of a translocation competent type III secreton. Finally, unlike the regulatory roles of other translocator-class chaperones (e.g., LcrH, SicA of Salmonella enterica, and IpgC of Shigella species), in vitro regulation of P. aeruginosa type III secretion does not involve PcrH.

Place, publisher, year, edition, pages
2003. Vol. 188, no 12, 1909-1921 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:umu:diva-4146DOI: 10.1086/379898PubMedID: 14673772OAI: oai:DiVA.org:umu-4146DiVA: diva2:143127
Available from: 2004-10-06 Created: 2004-10-06 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Type III secretion- the various functions of the translocon operon in bacterial pathogenesis
Open this publication in new window or tab >>Type III secretion- the various functions of the translocon operon in bacterial pathogenesis
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In order to establish colonisation of a human host, pathogenic Yersinia use a type III protein secretion system to directly intoxicate host immune cells. Activation of this system requires target cell contact and is a highly regulated process. Both the intoxication and regulation events depend on the lcrGVHyopBD translocon operon, which is highly conserved in many bacterial pathogens. In this study, the role of individual operon members was analysed and functional domains identified by using the highly homologous pcrGVHpopBD operon of P. aeruginosa as a comparative tool.

Yersinia spp. and P. aeruginosa were shown to form translocation pores of a similar size that promoted equally efficient protein delivery. A strong dependency on interactions between native translocator(s) in protein delivery was revealed, suggesting that each pathogen has delicately fine-tuned this process to suit its own infection niche. In particular, the C-terminus of YopD was shown to possess functional specificity for effector delivery in Yersinia that could not be conferred by the comparable region in homologous PopD. Moreover, a role for LcrV and PcrV in substrate recognition during the protein delivery process was excluded.

The N-terminus of LcrH was recognized as a unique regulatory domain, mediating formation of LcrH-YscY regulatory complexes in Yersinia, while equivalent complexes with analogous proteins were not formed in P. aeruginosa. These results compliment the idea that a negative regulatory pathway involving LcrH, YopD, LcrQ and YscY is unique to Yersinia.

Finally, PcrH was identified as a new member of the translocator class of chaperones, being essential for assembly of a functional PopB/PopD mediated translocon in P. aeruginosa. However, in contrast to the other members of this family, PcrH was dispensable for type III regulation. Moreover, both LcrH and PcrH were shown to possess tetratricopeptide repeats crucial for their chaperone function. One tetratricopeptide repeat mutant in LcrH was even isolated that failed to secrete both YopB and YopD substrates, even though stability was maintained. This demonstrates for the first time that LcrH has a role in substrate secretion in addition to its critical role in promoting substrate stability.

Place, publisher, year, edition, pages
Umeå: Molekylärbiologi, 2004. 82 p.
Keyword
Molecular biology, Yersinia, Pseudomonas aeruginosa, type III secretion, chaperone, translocation, regulation, lcrGVHyopBD, pcrGVHpopBD, Molekylärbiologi
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-331 (URN)91-7305-712-6 (ISBN)
Public defence
2004-11-05, Major Groove, 6L, NUS, Umeå Universitet, 90187, Umeå, 09:00
Opponent
Supervisors
Available from: 2004-10-06 Created: 2004-10-06Bibliographically approved

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