1. 1- N -histidine phosphorylation of ChlD by the AAA + ChlI2 stimulates magnesium chelatase activity in chlorophyll synthesis.
- Author
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Sawicki A, Zhou S, Kwiatkowski K, Luo M, and Willows RD
- Subjects
- Algal Proteins agonists, Algal Proteins chemistry, Algal Proteins genetics, Algal Proteins metabolism, Amino Acid Sequence, Amino Acid Substitution, Conserved Sequence, Enzyme Activation, Enzyme Stability, Histidine metabolism, Histidine Kinase chemistry, Histidine Kinase genetics, Hydrogen-Ion Concentration, Lyases chemistry, Lyases genetics, Mutation, Phosphorus Radioisotopes, Phosphorylation, Plant Proteins agonists, Plant Proteins chemistry, Plant Proteins genetics, Protein Interaction Domains and Motifs, Protein Multimerization, Proteomics methods, Chlamydomonas reinhardtii enzymology, Chlorophyll biosynthesis, Histidine Kinase metabolism, Lyases metabolism, Oryza enzymology, Plant Proteins metabolism, Protein Processing, Post-Translational
- Abstract
Magnesium chelatase (Mg-chelatase) inserts magnesium into protoporphyrin during the biosynthesis of chlorophyll and bacteriochlorophyll. Enzyme activity is reconstituted by forming two separate preactivated complexes consisting of a GUN4/ChlH/protoporphyrin IX substrate complex and a ChlI/ChlD enzyme 'motor' complex. Formation of the ChlI/ChlD complex in both Chlamydomonas reinhardtii and Oryza sativa is accompanied by phosphorylation of ChlD by ChlI, but the orthologous protein complex from Rhodobacter capsulatus , BchI/BchD, gives no detectable phosphorylation of BchD. Phosphorylation produces a 1- N -phospho-histidine within ChlD. Proteomic analysis indicates that phosphorylation occurs at a conserved His residue in the C-terminal integrin I domain of ChlD. Comparative analysis of the ChlD phosphorylation with enzyme activities of various ChlI/ChlD complexes correlates the phosphorylation by ChlI2 with stimulation of Mg-chelatase activity. Mutation of the H641 of CrChlD to E641 prevents both phosphorylation and stimulation of Mg-chelatase activity, confirming that phosphorylation at H641 stimulates Mg-chelatase. The properties of ChlI2 compared with ChlI1 of Chlamydomonas and with ChlI of Oryza , shows that ChlI2 has a regulatory role in Chlamydomonas ., (© 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.)
- Published
- 2017
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