The enzymatic activity of phosphoglycerate mutase from gram-positive endospore-forming bacteria requires Mn2+ and is pH sensitive.
The enzymatic activity of phosphoglycerate mutase (Pgm) from three gram-positive endospore-forming bacteria (Bacillus subtilis, Clostridium perfringens, and Sporosarcina ureae) requires Mn2+ and is very sensitive to pH; at low concentrations of Mn2+, a pH change from 8 to 6 resulted in greater than 30- to 200-fold decreases in the activity of these Pgms. However, Pgm deactivation at pH 6 was reversed by shifting the enzyme to pH 7 or 8. Free Mn2+ was not directly involved in Pgm catalysis, although enzyme-bound Mn2+ may be involved. The rate of catalysis by Mn(2+)-containing Pgm was also slightly pH dependent, although the Km for 3-phosphoglyceric acid appeared to be the same at pH 6, 7, and 8. These findings suggest that Mn2+ binds to catalytically inactive Pgm and converts it to a catalytically competent form, and further, that pH influences the efficiency with which the enzyme binds Mn2+. The extreme pH sensitivity of the Mn(2+)-dependent Pgms supports a model in which this enzyme is inhibited during sporulation by acidification of the forespore, thus allowing accumulation of the spore's large depot of 3-phosphoglyceric acid. The activity of Pgm from two closely related gram-positive bacteria that do not form spores (Planococcus citreus and Staphylococcus saprophyticus) also requires Mn2+ and is pH sensitive. In contrast, the Pgm activities from two more distantly related non-endospore-forming gram-positive bacteria (Micrococcus luteus and Streptomyces coelicolor) are neither dependent on metal ions nor particularly sensitive to pH.
Chander
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M
Department of Biochemistry, University of Connecticut Health Center, Farmington 06030, USA.
Setlow
B
B
Setlow
P
P
D001412:Bacillus subtilis / Q000201:enzymology; D003016:Clostridium perfringens / Q000201:enzymology; D016936:Gram-Positive Endospore-Forming Bacteria / Q000145:classification / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D016982:Micrococcus luteus / Q000201:enzymology; D010736:Phosphoglycerate Mutase / Q000378:metabolism*; D013045:Species Specificity; D013210:Staphylococcus / Q000201:enzymology; D013302:Streptomyces / Q000201:enzymology
D008345:Manganese; D010736:Phosphoglycerate Mutase