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A minimal Tat system from a gram-positive organism: a bifunctional TatA subunit participates in discrete TatAC and TatA complexes.

Barnett, James P., Eijlander, Robyn T., Kuipers, Oscar P., Robinson, Colin (2008) A minimal Tat system from a gram-positive organism: a bifunctional TatA subunit participates in discrete TatAC and TatA complexes. Journal of Biological Chemistry, 283 (5). pp. 2534-2542. ISSN 0021-9258. (doi:10.1074/jbc.M708134200) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1074/jbc.M708134200

Abstract

The Tat system transports folded proteins across bacterial and thylakoid membranes. In Gram-negative organisms, a TatABC substrate-binding complex and separate TatA complex are believed to coalesce to form an active translocon, with all three subunits essential for translocation. Most Gram-positive organisms lack a tatB gene, indicating major differences in organization and possible differences in mode of action. Here, we have studied Tat complexes encoded by the tatAdCd genes of Bacillus subtilis. Expression of tatAdCd in an Escherichia coli tat null mutant results in efficient export of a large, cofactor-containing E. coli Tat substrate, TorA. We show that the tatAd gene complements E. coli mutants lacking either tatAE or tatB, indicating a bifunctional role for this subunit in B. subtilis. Second, we have identified and characterized two distinct Tat complexes that are novel in key respects: a TatAdCd complex of approximately 230 kDa that is significantly smaller than the analogous E. coli TatABC complex (approximately 370 kDa on BN gels) and a separate TatAd complex. The latter is a discrete entity of approximately 270 kDa as judged by gel filtration chromatography, very different from the highly heterogeneous E. coli TatA complex that ranges in size from approximately 50 kDa to over 600 kDa. TatA heterogeneity has been linked to the varying size of Tat substrates being translocated, but the singular nature of the B. subtilis TatAd complex suggests that discrete TatAC and TatA complexes may form a single form of translocon.

Item Type: Article
DOI/Identification number: 10.1074/jbc.M708134200
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Colin Robinson
Date Deposited: 24 Jul 2013 15:53 UTC
Last Modified: 29 May 2019 10:26 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/34858 (The current URI for this page, for reference purposes)
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