Characteristics and sequence of phosphoglycolate phosphatase from a eukaryotic green alga Chlamydomonas reinhardtii


Creative Commons License

Mamedov T., Suzuki K., Miura K., Kucho K., Fukuzawa H.

JOURNAL OF BIOLOGICAL CHEMISTRY, vol.276, no.49, pp.45573-45579, 2001 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 276 Issue: 49
  • Publication Date: 2001
  • Doi Number: 10.1074/jbc.m103882200
  • Journal Name: JOURNAL OF BIOLOGICAL CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.45573-45579
  • Akdeniz University Affiliated: No

Abstract

Phosphoglycolate phosphatase (PGPase), a key enzyme of photorespiration in photosynthetic organisms, was purified from Chlamydomonas reinhardtii. The enzyme was an similar to 65-kDa homodimer with a pI value of 5.1 composed of similar to 32-kDa subunits not connected by any S-S bridges. It was also highly specific for phosphoglycolate with a K-m value of 140 mum and an optimal pH between 8 and 9. The activity was strongly inhibited by CaCl2, and it recovered competitively following the addition of MgCl2 or EGTA. A mobility shift was observed in SDS-polyacrylamide gel electrophoresis by the addition of CaCl2. indicating that the enzyme binds to Ca2+. The N-terminal region of amino acid sequence deduced from cDNA sequence that was not contained in the purified PGPase had similar characteristics to those of typical stroma-targeting transit peptides in C. reinhardtii. The following region of the deduced sequence containing 302 amino acid residues was similar to p-nitrophenylphosphatase-like proteins, although the purified PGPase did not hydrolyze p-nitrophenylphosphate. Genomic DNA fragments from wild type containing the sequence homologous to the cDNA for PGPase complemented the PGPase-deficient mutant pgp1. Possible regulatory mechanisms during adaptation to limiting CO2 were discussed based on the characteristics of the purified PGPase and the deduced amino acid sequence.