Compaction of a prokaryotic signal-anchor transmembrane domain begins within the ribosome tunnel and is stabilized by SRP during targeting

Robinson, P.J., Findlay, J.E. and Woolhead, C.A. (2012) Compaction of a prokaryotic signal-anchor transmembrane domain begins within the ribosome tunnel and is stabilized by SRP during targeting. Journal of Molecular Biology, 423(4), pp. 600-612. (doi:10.1016/j.jmb.2012.07.023)

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Abstract

Cotranslational targeting of membrane proteins is mediated by the universally conserved signal recognition particle (SRP). In eukaryotes, SRP attenuates translation during targeting; however, in prokaryotes, a simplified SRP is believed to carry out targeting during continuing translation. Here, we show a detailed stepwise analysis of the targeting of subunit c of the F0 component of the bacterial ATP synthase (F0c) to the inner membrane. We show that the first transmembrane (TM) signal-anchor domain of F0c forms a compacted structure within the distal portion of the ribosome tunnel. This structure is formed just prior to the interaction with SRP. In the absence of SRP this structure is lost as the TM domain exits the tunnel; however in the presence of SRP it is stabilized. Our results suggest differences in early protein folding of substrates for prokaryotic SRP‐dependent membrane protein targeting pathways, from that of eukaryotic SRP targeting. These results imply that early TM domain recognition by targeting factors acts to ensure that the efficiency of membrane targeting is maintained.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Robinson, Dr Philip and Woolhead, Dr Cheryl and Findlay, Mrs Jane
Authors: Robinson, P.J., Findlay, J.E., and Woolhead, C.A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Journal of Molecular Biology
Publisher:Elsevier
ISSN:0022-2836
Published Online:04 August 2012

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
496961Folding and insertion of a bacterial inner membrane proteinCheryl WoolheadBiotechnology and Biological Sciences Research Council (BBSRC)BB/G011281/1RI MOLECULAR CELL & SYSTEMS BIOLOGY