1. The chloroplast ClpP complex in Chlamydomonas reinhardtii contains an unusual high molecular mass subunit with a large apical domain
- Author
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Klaas J. van Wijk, Olivier Vallon, Giulia Friso, and Wojciech Majeran
- Subjects
Chloroplasts ,Protein subunit ,Molecular Sequence Data ,Chlamydomonas reinhardtii ,Sequence alignment ,Biology ,Biochemistry ,Protein structure ,Enzyme Stability ,Animals ,Amino Acid Sequence ,Plastid ,Molecular Biology ,Peptide sequence ,Phylogeny ,Cell Nucleus ,Sequence Homology, Amino Acid ,Endopeptidase Clp ,Cell Biology ,biology.organism_classification ,Molecular biology ,Protein Structure, Tertiary ,Molecular Weight ,Chloroplast ,Protein Subunits ,Chaperone (protein) ,biology.protein ,Sequence Alignment ,Protein Binding - Abstract
The composition of the chloroplast-localized protease complex, ClpP, from the green alga Chlamydomonas reinhardtii was characterized by nondenaturing electrophoresis, immunoblotting and MS. The detected ClpP complex has a native mass of approximately 540 kDa, which is approximately 200 kDa higher than ClpP complexes in higher plant chloroplasts, mitochondria or bacteria. The 540-kDa ClpP complex contains two nuclear-encoded ClpP proteins (ClpP3 and P5) and five ClpR (R1, R2, R3, R4 and R6) proteins, as well two proteins, ClpP1L and ClpP1H, both probably derived from the plastid clpP1 gene. ClpP1H is 59 kDa and contains a approximately 30-kDa insertion sequence (IS1) not found in other ClpP proteins, responsible for the high MW of the complex. Based on comparison with other sequences, IS1 protrudes as an additional domain on the apical surface of the ClpP/R complex, probably preventing interaction with the HSP100 chaperone. ClpP1L is a 25-kDa protein similar in size to other ClpP proteins and could arise by post-translational processing of ClpP1H. Chloramphenicol-chase experiments show that ClpP1L and ClpP1H have a similar half-life, indicating that both are stable components of the complex. The structure of the ClpP complex is further discussed in conjunction with a phylogenetic analysis of the ClpP/R genes. A model is proposed for the evolution of the algal and plant complex from its cyanobacterial ancestor.
- Published
- 2005
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