Open AccessAltered substrate specificity by substitutions at Tyr218 in bacterial aminoglycoside 3′‐phosphotransferase‐II
Author(s) -
Kocabiyik Semra,
Perlin Michael H.
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05090.x
Subject(s) - aminoglycoside , pep group translocation , phosphotransferase , substrate specificity , substrate (aquarium) , phosphotransferases , microbiology and biotechnology , chemistry , biochemistry , biology , antibiotics , enzyme , phosphoenolpyruvate carboxykinase , ecology
Mutant aminoglycoside 3′‐phosphotransferase II enzymes were produced in which Tyr218 was changed to serine, aspartic acid, or phenylalanine. In each case the mutation resulted in increased bacterial susceptibility to neomycin and kanamycin, while simultaneously increasing the K m values for these substrates. For the Ser and Asp mutants, bacterial resistance to amikacin increased, with a concomitant increase in affinity for this drug. Initial velocity studies indicated that the wild‐type and mutant enzymes all followed Michaelis‐Menten kinetics. Although these mutagenic substitutions changed the substrate specificity of these enzymes they did not alter the enzyme affinity for Mg 2+ ‐ATP.