Phosphoglycerate mutase is a highly efficient enzyme without flux control in Lactococcus lactis.
The glycolytic enzyme phosphoglycerate mutase (PGM), which catalyzes the conversion of 3-phosphoglycerate to 2-phosphoglycerate, was examined in Lactococcus lactis with respect to its function, kinetics and glycolytic flux control. A library of strains with PGM activities ranging between 15-465% of the wild-type level was constructed by replacing the native promoter of pgm with synthetic promoters of varying strengths. The specific growth rate and glucose flux were found to be maximal at the wild-type level at which PGM had no flux control. Low flux control of PGM was found on mixed acid fluxes at highly reduced PGM activities. At the wild-type level PGM operated very far from V(max). Consequently, in a strain with only 15% PGM activity, the catalytic rate of PGM was almost six times higher than in the wild-type. K(m)of PGM for 3-phosphoglycerate was 1.0 mM and k(cat)was 3,200 s(-1). The L. lactis PGM was dependent on 2,3-bisphosphoglyceric acid for activity, which showed that the enzyme is of the dPGM type in accordance with its predicted homology to dPGM enzymes from other organisms. In conclusion, PGM from L. lactis is a highly efficient catalyst, which partially explains why this enzyme has limited control in wild-type L. lactis.
Solem
Christian
C
Department of Systems Biology, Center for Systems Microbiology, Technical University of Denmark, Kongens Lyngby, Denmark.
Petranovic
Dina
D
Koebmann
Brian
B
Mijakovic
Ivan
I
Jensen
Peter Ruhdal
PR
D019794:2,3-Diphosphoglycerate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D016000:Cluster Analysis; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D005988:Glyceric Acids / Q000378:metabolism; D007700:Kinetics; D013294:Lactococcus lactis / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D010736:Phosphoglycerate Mutase / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment
D001426:Bacterial Proteins; D005988:Glyceric Acids; D019794:2,3-Diphosphoglycerate; C005156:3-phosphoglycerate; D010736:Phosphoglycerate Mutase; D005947:Glucose