Evidence for phosphotransferases phosphorylated on aspartate residue in N-terminal DXDX(T/V) motif

Abstract

The group of enzymes forming a phosphoaspartate intermediate comprises P-type ATPases, bacterial protein phosphatases acting in signal transduction, and a newly identified class of phosphotransferases that is characterized by a conserved DXDXT/V motif close to the N terminus. The chapter shows the formation of an acyl-phosphate for the following enzymes: spinach phosphoglycolate phosphatase, human phospho serine phosphatase, human phosphomannomutases 1 and 2, and Lactococcus lactis β- phosphoglucomutase.The position of the phosphorylated residue was identified as the first aspartate in the DXDXT/V motif in human phosphomannomutase and in human phosphoserine phosphatase. Results of site-directed mutagenesis of the two aspartates in phosphomannomutase and in phosphoserine phosphatase are compatible with this conclusion. In most of these enzymes, the DXDXT/V motif is located close to the N terminus. An exception—such as yeast trehalose-6-phosphate phosphatase —is because of the fact that this enzyme is bifunctional, with a trehalose-6-phosphate synthase domain N-terminal to the phosphatase domain. Other exceptions may correspond to proteins with several domains.