Novel Thylakoid Membrane GreenCut Protein CPLD38 Impacts Accumulation of the Cytochrome b6f Complex and Associated Regulatory Processes
- Carnegie Inst. for Science, Stanford, CA (United States). Dept. of Plant Biology
- Carnegie Inst. for Science, Stanford, CA (United States). Dept. of Plant Biology; Univ. Pierre et Marie Curie, Paris (France). Centre National de la Recherche Scientifique (CNRS). Inst. de Biologie Physico-Chimique. UMR 7141
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Division; Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst. Dept. of Platn and Microbial Biology
- Univ. Pierre et Marie Curie, Paris (France). Centre National de la Recherche Scientifique (CNRS). Inst. de Biologie Physico-Chimique. UMR 7141
Background: The GreenCut is a group of ~600 green-lineage-specific proteins hypothetically involved in photosynthesis. Results: A Chlamydomonas reinhardtii mutant disrupted for GreenCut gene CPLD38 has a marked reduction in cytochrome b6f and an increase in chlororespiration. Conclusion: CPLD38 is essential for accumulating cytochrome b6f and balancing chlororespiration and photosynthesis. Significance: This analysis demonstrates the importance of a GreenCut protein in photosynthesis. Based on previous comparative genomic analyses, a set of nearly 600 polypeptides was identified that is present in green algae and flowering and nonflowering plants but is not present (or is highly diverged) in nonphotosynthetic organisms. The gene encoding one of these “GreenCut” proteins, CPLD38, is in the same operon as ndhL in most cyanobacteria; the NdhL protein is part of a complex essential for cyanobacterial respiration. A cpld38 mutant of Chlamydomonas reinhardtii does not grow on minimal medium, is high light-sensitive under photoheterotrophic conditions, has lower accumulation of photosynthetic complexes, reduced photosynthetic electron flow to P700+, and reduced photochemical efficiency of photosystem II (PSII); these phenotypes are rescued by a wild-type copy of CPLD38. Single turnover flash experiments and biochemical analyses demonstrated that cytochrome b6f function was severely compromised, and the levels of transcripts and polypeptide subunits of the cytochrome b6f complex were also significantly lower in the cpld38 mutant. Furthermore, subunits of the cytochrome b6f complex in mutant cells turned over much more rapidly than in wild-type cells. Interestingly, PTOX2 and NDA2, two major proteins involved in chlororespiration, were more than 5-fold higher in mutants relative to wild-type cells, suggesting a shift in the cpld38 mutant from photosynthesis toward chlororespiratory metabolism, which is supported by experiments that quantify the reduction state of the plastoquinone pool. Together, these findings support the hypothesis that CPLD38 impacts the stability of the cytochrome b6f complex and possibly plays a role in balancing redox inputs to the quinone pool from photosynthesis and chlororespiration.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division; National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-05CH11231; MCB0824469; MCB0235878
- OSTI ID:
- 1625079
- Journal Information:
- Journal of Biological Chemistry, Vol. 288, Issue 10; ISSN 0021-9258
- Publisher:
- American Society for Biochemistry and Molecular BiologyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
GreenCut protein
Correlation between changes in light energy distribution and changes in thylakoid membrane polypeptide phosphorylation in Chlamydomonas reinhardtii