| 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]
Publication Abstract from PubMed
Chloroplasts contain a unique signal recognition particle (cpSRP). Unlike the cytoplasmic forms, the cpSRP lacks RNA but contains a conserved 54-kDa GTPase and a novel 43-kDa subunit (cpSRP43). Recently, three functionally distinct chromodomains (CDs) have been identified in cpSRP43. In the present study, we report the three-dimensional solution structures of the three CDs (CD1, CD2, and CD3) using a variety of triple resonance NMR experiments. The structure of CD1 consists of a triple-stranded beta-sheet segment. The C-terminal helical segment typically found in the nuclear chromodomains is absent in CD1. The secondary structural elements in CD2 and CD3 include a triple-stranded antiparallel beta-sheet and a C-terminal helix. Interestingly, the orientation of the C-terminal helix is significantly different in the structures of CD2 and CD3. Critical comparison of the structures of the chromodomains of cpSRP43 with those found in nuclear chromodomain proteins revealed that the diverse protein-protein interactions mediated by the CDs appear to stem from the differences that exist in the surface charge potentials of each CD. Results of isothermal titration calorimetry experiments confirmed that only CD2 is involved in binding to cpSRP54. The negatively charged C-terminal helix in CD2 possibly plays a crucial role in the cpSRP54-cpSRP43 interaction.
Three-dimensional solution structures of the chromodomains of cpSRP43.,Sivaraja V, Kumar TK, Leena PS, Chang AN, Vidya C, Goforth RL, Rajalingam D, Arvind K, Ye JL, Chou J, Henry R, Yu C J Biol Chem. 2005 Dec 16;280(50):41465-71. Epub 2005 Sep 23. PMID:16183644[6]
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
- ↑ Sivaraja V, Kumar TK, Leena PS, Chang AN, Vidya C, Goforth RL, Rajalingam D, Arvind K, Ye JL, Chou J, Henry R, Yu C. Three-dimensional solution structures of the chromodomains of cpSRP43. J Biol Chem. 2005 Dec 16;280(50):41465-71. Epub 2005 Sep 23. PMID:16183644 doi:M507077200
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