Kinetic mechanism of streptomycin adenylyltransferase from a recombinant Escherichia coli.
Bacterial resistance to the aminoglycoside antibiotics is manifested primarily by enzymic modification of these drugs. One important mechanism of streptomycin modification is through ATP-dependent O-adenylation, catalyzed by streptomycin adenylyltransferase. Initial velocity patterns deduced from steady state kinetics indicate a sequential mechanism. Dead-end inhibition by tobramycin and neomycin is non-competitive versus streptomycin and uncompetitive versus ATP, indicative of ordered substrate binding where ATP binds first and then streptomycin. These results surmise that streptomycin adenylyltransferase follows an ordered, sequential kinetic mechanism in which one substrate (ATP) binds prior to the antibiotic and pyrophosphate is released prior to formation of AMP-streptomycin.
Jana
Snehasis
S
Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology-Delhi, Hauz Khas, New Delhi 110016, India. janasnehasis@rediffmail.com
Deb
J K
JK
D000255:Adenosine Triphosphate / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D007700:Kinetics; D009355:Neomycin / Q000494:pharmacology; D009713:Nucleotidyltransferases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013307:Streptomycin / Q000378:metabolism; D014031:Tobramycin / Q000494:pharmacology
D011756:Diphosphates; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D009713:Nucleotidyltransferases; C022678:streptomycin 3''-adenylyltransferase; D009355:Neomycin; D014031:Tobramycin; D013307:Streptomycin