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Crystal structure of the N-terminal Domain of Caseinolytic protease associated chaperone ClpC1 from Arabidopsis thalianaCrystal structure of the N-terminal Domain of Caseinolytic protease associated chaperone ClpC1 from Arabidopsis thaliana
Structural highlights
FunctionCLPC1_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 PubMedThe 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. See AlsoReferences
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