| Structural highlights
Function
[SR43C_ARATH] Component of the chloroplast signal recognition particle pathway. Required for post-translational targeting of proteins into the tylakoid membrane but seems to be dispensable for co-translational targeting with a translating ribosome present. May be able to function independently of cpFTSY and FFC/cpSRP54 in targeting LHCPs to the thylakoids. Acts as a highly specific chaperone for LHCPs, preventing aggregation and being able to dissolve aggregates.[1] [2] [3] [4] [5] [SR54C_ARATH] Involved in cotranslational and post-translational sorting of thylakoid proteins. Binds GTP specifically. Activates the GTPase activity of CPFTSY when bound together. Required for light-harvesting chlorophyll a/b-binding protein (LHCP) integration into thylakoids.[6] [7] [8] [9]
Publication Abstract from PubMed
Signal recognition particle in chloroplasts (cpSRP) exhibits the unusual ability to bind and target full-length proteins to the thylakoid membrane. Unlike cytosolic SRPs in prokaryotes and eukaryotes, cpSRP lacks an RNA moiety and functions as a heterodimer composed of a conserved 54-kDa guanosine triphosphatase (cpSRP54) and a unique 43-kDa subunit (cpSRP43). Assembly of the cpSRP heterodimer is a prerequisite for post-translational targeting activities and takes place through interactions between chromatin modifier domain 2 (CD2) of cpSRP43 and a unique 10-amino-acid region in cpSRP54 (cpSRP54(pep)). We have used multidimensional NMR spectroscopy and other biophysical methods to examine the assembly and structure of the cpSRP43-cpSRP54 interface. Our data show that CD2 of cpSRP43 binds to cpSRP54(pep) in a 1:1 stoichiometry with an apparent K(d) of approximately 1.06 muM. Steady-state fluorescence and far-UV circular dichroism data suggest that the CD2-cpSRP54(pep) interaction causes significant conformational changes in both CD2 and the peptide. Comparison of the three-dimensional solution structures of CD2 alone and in complex with cpSRP54(pep) shows that significant structural changes are induced in CD2 in order to establish a binding interface contributed mostly by residues in the N-terminal segment of CD2 (Phe5-Val10) and an arginine doublet (Arg536 and Arg537) in the cpSRP54 peptide. Taken together, our results provide new insights into the mechanism of cpSRP assembly and the structural forces that stabilize the functionally critical cpSRP43-cpSRP54 interaction.
Assembly of chloroplast signal recognition particle involves structural rearrangement in cpSRP43.,Kathir KM, Rajalingam D, Sivaraja V, Kight A, Goforth RL, Yu C, Henry R, Kumar TK J Mol Biol. 2008 Aug 1;381(1):49-60. Epub 2008 Jun 3. PMID:18586266[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Klimyuk VI, Persello-Cartieaux F, Havaux M, Contard-David P, Schuenemann D, Meiherhoff K, Gouet P, Jones JD, Hoffman NE, Nussaume L. A chromodomain protein encoded by the arabidopsis CAO gene is a plant-specific component of the chloroplast signal recognition particle pathway that is involved in LHCP targeting. Plant Cell. 1999 Jan;11(1):87-99. PMID:9878634
- ↑ Tu CJ, Schuenemann D, Hoffman NE. Chloroplast FtsY, chloroplast signal recognition particle, and GTP are required to reconstitute the soluble phase of light-harvesting chlorophyll protein transport into thylakoid membranes. J Biol Chem. 1999 Sep 17;274(38):27219-24. PMID:10480939
- ↑ Goforth RL, Peterson EC, Yuan J, Moore MJ, Kight AD, Lohse MB, Sakon J, Henry RL. Regulation of the GTPase cycle in post-translational signal recognition particle-based protein targeting involves cpSRP43. J Biol Chem. 2004 Oct 8;279(41):43077-84. Epub 2004 Aug 2. PMID:15292240 doi:http://dx.doi.org/10.1074/jbc.M401600200
- ↑ Tzvetkova-Chevolleau T, Hutin C, Noel LD, Goforth R, Carde JP, Caffarri S, Sinning I, Groves M, Teulon JM, Hoffman NE, Henry R, Havaux M, Nussaume L. Canonical signal recognition particle components can be bypassed for posttranslational protein targeting in chloroplasts. Plant Cell. 2007 May;19(5):1635-48. Epub 2007 May 18. PMID:17513500 doi:http://dx.doi.org/10.1105/tpc.106.048959
- ↑ Falk S, Sinning I. cpSRP43 is a novel chaperone specific for light-harvesting chlorophyll a,b-binding proteins. J Biol Chem. 2010 Jul 9;285(28):21655-61. doi: 10.1074/jbc.C110.132746. Epub 2010, May 24. PMID:20498370 doi:http://dx.doi.org/10.1074/jbc.C110.132746
- ↑ Tu CJ, Schuenemann D, Hoffman NE. Chloroplast FtsY, chloroplast signal recognition particle, and GTP are required to reconstitute the soluble phase of light-harvesting chlorophyll protein transport into thylakoid membranes. J Biol Chem. 1999 Sep 17;274(38):27219-24. PMID:10480939
- ↑ Groves MR, Mant A, Kuhn A, Koch J, Dubel S, Robinson C, Sinning I. Functional characterization of recombinant chloroplast signal recognition particle. J Biol Chem. 2001 Jul 27;276(30):27778-86. Epub 2001 May 16. PMID:11356852 doi:http://dx.doi.org/10.1074/jbc.M103470200
- ↑ Jaru-Ampornpan P, Chandrasekar S, Shan SO. Efficient interaction between two GTPases allows the chloroplast SRP pathway to bypass the requirement for an SRP RNA. Mol Biol Cell. 2007 Jul;18(7):2636-45. Epub 2007 May 2. PMID:17475780 doi:http://dx.doi.org/10.1091/mbc.E07-01-0037
- ↑ Rutschow H, Ytterberg AJ, Friso G, Nilsson R, van Wijk KJ. Quantitative proteomics of a chloroplast SRP54 sorting mutant and its genetic interactions with CLPC1 in Arabidopsis. Plant Physiol. 2008 Sep;148(1):156-75. doi: 10.1104/pp.108.124545. Epub 2008 Jul , 16. PMID:18633119 doi:http://dx.doi.org/10.1104/pp.108.124545
- ↑ Kathir KM, Rajalingam D, Sivaraja V, Kight A, Goforth RL, Yu C, Henry R, Kumar TK. Assembly of chloroplast signal recognition particle involves structural rearrangement in cpSRP43. J Mol Biol. 2008 Aug 1;381(1):49-60. Epub 2008 Jun 3. PMID:18586266 doi:http://dx.doi.org/10.1016/j.jmb.2008.05.065
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