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.
2-Carboxy-D-arabinitol 1-phosphate (CA1P) phosphatase: evidence for a wider role in plant Rubisco regulation
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Paul John Andralojc, Pippa J. Madgwick, Yong Tao, Alfred Keys, Jane L. Ward, Michael H. Beale, Jane E. Loveland, Phil J. Jackson, Antony C. Willis, Steven Gutteridge, Martin A.J. Parry; 2-Carboxy-D-arabinitol 1-phosphate (CA1P) phosphatase: evidence for a wider role in plant Rubisco regulation. Biochem J 15 March 2012; 442 (3): 733–742. doi: https://doi.org/10.1042/BJ20111443
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