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Binding of chloroplast signal recognition particle to a thylakoid membrane protein substrate in aqueous solution and delineation of the cpSRP43–substrate interaction domain
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Cain, Peter, Holdermann, Iris, Sinning, Irmgard, Johnson, Arthur E. and Robinson, Colin (2011) Binding of chloroplast signal recognition particle to a thylakoid membrane protein substrate in aqueous solution and delineation of the cpSRP43–substrate interaction domain. Biochemical Journal, Vol.437 (No.1). pp. 149-155. doi:10.1042/BJ20110270 ISSN 0264-6021.
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Official URL: http://dx.doi.org/10.1042/BJ20110270
Abstract
A cpSRP [chloroplast SRP (signal recognition particle)] comprising cpSRP54 and cpSRP43 subunits mediates the insertion of light-harvesting proteins into the thylakoid membrane. We dissected its interaction with a full-length membrane protein substrate in aqueous solution by insertion of site-specific photoactivatable cross-linkers into in vitro-synthesized Lhcb1 (major light-harvesting chlorophyll-binding protein of photosystem II). We show that Lhcb1 residues 166-176 cross-link specifically to the cpSRP43 subunit. Some cross-link positions within Lhcb1 are in the 'L18' peptide required for targeting of cpSRP substrates, whereas other cross-linking positions define a new targeting signal in the third transmembrane span. Lhcb1 was not found to cross-link to cpSRP54 at any position, and cross-linking to cpSRP43 is unaffected by the absence of cpSRP54. cpSRP43 thus effectively binds substrates autonomously, and its ability to independently bind an extended 20+-residue substrate region highlights a major difference with other SRP types where the SRP54 subunit binds to hydrophobic target sequences. The results also show that cpSRP43 can bind to a hydrophobic, three-membrane span, substrate in aqueous solution, presumably reflecting a role for cpSRP in the chloroplast stroma. This mode of action, and the specificity of the cpSRP43 substrate interaction, may be associated with cpSRP's unique post-translational mode of action.
Item Type: | Journal Article | ||||
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Subjects: | Q Science > QK Botany | ||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- ) | ||||
Library of Congress Subject Headings (LCSH): | Chloroplasts -- Physiology, Plant proteins | ||||
Journal or Publication Title: | Biochemical Journal | ||||
Publisher: | Portland Press | ||||
ISSN: | 0264-6021 | ||||
Official Date: | 1 July 2011 | ||||
Dates: |
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Volume: | Vol.437 | ||||
Number: | No.1 | ||||
Page Range: | pp. 149-155 | ||||
DOI: | 10.1042/BJ20110270 | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access | ||||
Date of first compliant deposit: | 18 December 2015 | ||||
Date of first compliant Open Access: | 18 December 2015 | ||||
Funder: | Biotechnology and Biological Sciences Research Council (Great Britain) (BBSRC), National Institutes of Health (U.S.) (NIH), Robert A. Welch Foundation | ||||
Grant number: | GM26494 (NIH), BE-0017 (Robert A. Welch Foundation) |
Data sourced from Thomson Reuters' Web of Knowledge
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