title: A new class of phosphotransferases phosphorylated on an aspartate residue in an amino-terminal DXDX(T/V) motif.
abstract: When incubated with their substrates, human phosphomannomutase and L-3-phosphoserine phosphatase are known to form phosphoenzymes with chemical characteristics of an acyl-phosphate. The phosphorylated residue in phosphomannomutase has now been identified by mass spectrometry after reduction of the phosphoenzyme with tritiated borohydride and trypsin digestion. It is the first aspartate in a conserved DVDGT motif. Replacement of either aspartate of this motif by asparagine or glutamate resulted in complete inactivation of the enzyme. The same mutations performed in the DXDST motif of L-3-phosphoserine phosphatase also resulted in complete inactivation of the enzyme, except for the replacement of the second aspartate by glutamate, which reduced the activity by only about 40%. This suggests that the first aspartate of the motif is also the phosphorylated residue in L-3-phosphoserine phosphatase. Data banks contained seven other phosphomutases or phosphatases sharing a similar, totally conserved DXDX(T/V) motif at their amino terminus. One of these (beta-phosphoglucomutase) is shown to form a phosphoenzyme with the characteristics of an acyl-phosphate. In conclusion, phosphomannomutase and L-3-phosphoserine phosphatase belong to a new phosphotransferase family with an amino-terminal DXDX(T/V) motif that serves as an intermediate phosphoryl acceptor.
authors.affiliation: Laboratory of Physiological Chemistry, Christian de Duve Institute of Cellular Pathology and Catholic University of Louvain, B-1200 Brussels, Belgium.
authors.forename: J F
authors.initials: JF
authors.lastname: Collet
authors.forename: V
authors.initials: V
authors.lastname: Stroobant
authors.forename: M
authors.initials: M
authors.lastname: Pirard
authors.forename: G
authors.initials: G
authors.lastname: Delpierre
authors.forename: E
authors.initials: E
authors.lastname: Van Schaftingen
mesh_terms: D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry; D001894:Borohydrides / Q000378:metabolism; D017124:Conserved Sequence; D016208:Databases, Factual; D006801:Humans; D006867:Hydrolases / Q000737:chemistry; D007778:Lactobacillus / Q000201:enzymology; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics; D010766:Phosphorylation; D010770:Phosphotransferases / Q000737:chemistry* / Q000235:genetics; D017875:Phosphotransferases (Phosphomutases) / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry; D016415:Sequence Alignment; D014357:Trypsin / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001894:Borohydrides; D010446:Peptide Fragments; D011994:Recombinant Proteins; D001224:Aspartic Acid; C025364:sodium borohydride; D010770:Phosphotransferases; D006867:Hydrolases; D010744:Phosphoric Monoester Hydrolases; C022394:phosphoserine phosphatase; D014357:Trypsin; C034507:2-haloacid dehalogenase; D017875:Phosphotransferases (Phosphomutases); C052799:phosphomannomutase