| Structural highlights
Function
[CLPC1_ARATH] Molecular chaperone that hydrolyzes ATP and is associated with the chloroplast protein import apparatus. May function as the motor for chloroplast protein translocation, as translocation requires ATP hydrolysis in the stroma. May interact with a ClpP-like protease involved in degradation of denatured proteins in the chloroplast. Involved in the regulation of chlorophyll b biosynthesis through the destabilization of chlorophyllide a oxygenase (CAO) protein in response to the accumulation of chlorophyll b. Involved in leaf iron homeostasis.[1] [2] [3] [4] [5] [6] [7] [8]
Publication Abstract from PubMed
The caseinolytic protease machinery associated chaperone protein ClpC is known to be present in bacteria, plants and other eukaryotes, whereas ClpD is unique to plants. Plant ClpC and ClpD proteins get localized into chloroplast stroma. Herein, we report high resolution crystal structures of the N-terminal domain of Arabidopsis thaliana ClpC1 and ClpD. Surprisingly, AtClpD, but not AtClpC1, deviates from the typical N-terminal repeat domain organization of known Clp chaperones and have only seven alpha-helices, instead of eight. In addition, the loop connecting the two halves of AtClpD NTD is longer and covers the region which in case of AtClpC1 is thought to contribute to adaptor protein interaction. Taken together, the N-terminal domain of AtClpD has a divergent structural organization compared to any known Clp chaperones which hints towards its specific role during plant stress conditions, as opposed to that in the maintenance of chloroplastic homeostasis by AtClpC1. Conservation of residues in the NTD that are responsible for the binding of the cyclic peptide activator - Cyclomarin A, as reported for mycobacterial ClpC1 suggests that the peptide could be used as an activator to both AtClpC1 and AtClpD, which could be useful in their detailed in vitro functional characterization.
Crystal structures reveal N-terminal Domain of Arabidopsis thaliana ClpD to be highly divergent from that of ClpC1.,Mohapatra C, Kumar Jagdev M, Vasudevan D Sci Rep. 2017 Mar 13;7:44366. doi: 10.1038/srep44366. PMID:28287170[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Park S, Rodermel SR. Mutations in ClpC2/Hsp100 suppress the requirement for FtsH in thylakoid membrane biogenesis. Proc Natl Acad Sci U S A. 2004 Aug 24;101(34):12765-70. Epub 2004 Aug 10. PMID:15304652 doi:https://dx.doi.org/10.1073/pnas.0402764101
- ↑ Constan D, Froehlich JE, Rangarajan S, Keegstra K. A stromal Hsp100 protein is required for normal chloroplast development and function in Arabidopsis. Plant Physiol. 2004 Nov;136(3):3605-15. Epub 2004 Oct 29. PMID:15516497 doi:https://dx.doi.org/10.1104/pp.104.052928
- ↑ Kovacheva S, Bedard J, Patel R, Dudley P, Twell D, Rios G, Koncz C, Jarvis P. In vivo studies on the roles of Tic110, Tic40 and Hsp93 during chloroplast protein import. Plant J. 2005 Feb;41(3):412-28. PMID:15659100 doi:https://dx.doi.org/10.1111/j.1365-313X.2004.02307.x
- ↑ Nakagawara E, Sakuraba Y, Yamasato A, Tanaka R, Tanaka A. Clp protease controls chlorophyll b synthesis by regulating the level of chlorophyllide a oxygenase. Plant J. 2007 Mar;49(5):800-9. Epub 2007 Feb 9. PMID:17291312 doi:https://dx.doi.org/10.1111/j.1365-313X.2006.02996.x
- ↑ Kovacheva S, Bedard J, Wardle A, Patel R, Jarvis P. Further in vivo studies on the role of the molecular chaperone, Hsp93, in plastid protein import. Plant J. 2007 Apr;50(2):364-79. Epub 2007 Mar 21. PMID:17376159 doi:https://dx.doi.org/10.1111/j.1365-313X.2007.03060.x
- ↑ Wu H, Ji Y, Du J, Kong D, Liang H, Ling HQ. ClpC1, an ATP-dependent Clp protease in plastids, is involved in iron homeostasis in Arabidopsis leaves. Ann Bot. 2010 May;105(5):823-33. doi: 10.1093/aob/mcq051. Epub 2010 Apr 9. PMID:20382967 doi:https://dx.doi.org/10.1093/aob/mcq051
- ↑ Chu CC, Li HM. The amino-terminal domain of chloroplast Hsp93 is important for its membrane association and functions in vivo. Plant Physiol. 2012 Apr;158(4):1656-65. doi: 10.1104/pp.112.193300. Epub 2012 Feb, 21. PMID:22353577 doi:https://dx.doi.org/10.1104/pp.112.193300
- ↑ Sjogren LL, Tanabe N, Lymperopoulos P, Khan NZ, Rodermel SR, Aronsson H, Clarke AK. Quantitative analysis of the chloroplast molecular chaperone ClpC/Hsp93 in Arabidopsis reveals new insights into its localization, interaction with the Clp proteolytic core, and functional importance. J Biol Chem. 2014 Apr 18;289(16):11318-30. doi: 10.1074/jbc.M113.534552. Epub, 2014 Mar 5. PMID:24599948 doi:https://dx.doi.org/10.1074/jbc.M113.534552
- ↑ Mohapatra C, Kumar Jagdev M, Vasudevan D. Crystal structures reveal N-terminal Domain of Arabidopsis thaliana ClpD to be highly divergent from that of ClpC1. Sci Rep. 2017 Mar 13;7:44366. doi: 10.1038/srep44366. PMID:28287170 doi:https://dx.doi.org/10.1038/srep44366
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