2-Carboxy-D-arabinitol 1-phosphate (CA1P) phosphatase: evidence for a wider role in plant Rubisco regulation

• Published in: Biochemical journal Vol. 442; no. 3; p. 733
• Main Authors: Andralojc, Paul John, Madgwick, Pippa J, Tao, Yong, Keys, Alfred, Ward, Jane L, Beale, Michael H, Loveland, Jane E, Jackson, Phil J, Willis, Antony C, Gutteridge, Steven, Parry, Martin A J
• Format: Journal Article
• Language: English
• Published: England 15-03-2012
• Subjects: Amino Acid Sequence; Arabidopsis - enzymology; Kinetics; Molecular Sequence Data; Nicotiana - enzymology; Pentosephosphates - metabolism; Phaseolus - enzymology; Phosphoric Monoester Hydrolases - metabolism; Plant Proteins - metabolism; Ribulose-Bisphosphate Carboxylase - metabolism; Substrate Specificity; Triticum - enzymology
• ISSN: 1470-8728
• DOI: 10.1042/bj20111443

The genes for CA1Pase (2-carboxy-D-arabinitol-1-bisphosphate phosphatase) from French bean, wheat, Arabidopsis and tobacco were identified and cloned. The deduced protein sequence included an N-terminal motif identical with the PGM (phosphoglycerate mutase) active site sequence [LIVM]-x-R-H-G-[EQ]-x-x-[WN]. The corresponding gene from wheat coded for an enzyme with the properties published for CA1Pase. The expressed protein lacked PGM activity but rapidly dephosphorylated 2,3-DPG (2,3-diphosphoglycerate) to 2-phosphoglycerate. DTT (dithiothreitol) activation and GSSG inactivation of this enzyme was pH-sensitive, the greatest difference being apparent at pH 8. The presence of the expressed protein during in vitro measurement of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) activity prevented a progressive decline in Rubisco turnover. This was due to the removal of an inhibitory bisphosphate that was present in the RuBP (ribulose-1,5-bisphosphate) preparation, and was found to be PDBP (D-glycero-2,3-pentodiulose-1,5-bisphosphate). The substrate specificity of the expressed protein indicates a role for CA1Pase in the removal of 'misfire' products of Rubisco.