Bulky "gatekeeper" residue changes the cosubstrate specificity of aminoglycoside 2''-phosphotransferase IIa.
Bulky "gatekeeper" residue changes the cosubstrate specificity of aminoglycoside 2''-phosphotransferase IIa.
复制标题
庞大的“看门人”残基改变了氨基糖苷 2-磷酸转移酶 IIa 的共底物特异性。
DOI：
10.1128/aac.00381-13
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发表时间：
2013
影响因子：
4.9
通讯作者：
Vakulenko,SergeiB
中科院分区：
文献类型：
--
作者：
Bhattacharya,Monolekha;Toth,Marta;Smith,ClydeA;Vakulenko,SergeiB
The aminoglycoside 2″-phosphotransferases APH(2″)-IIa and APH(2″)-IVa can utilize ATP and GTP as cosubstrates, since both enzymes possess overlapping but discrete structural templates for ATP and GTP binding. APH(2″)-IIIa uses GTP exclusively, because its ATP-binding template is blocked by a bulky tyrosine “gatekeeper” residue. Replacement of the “gatekeeper” residues M85 and F95 in APH(2″)-IIa and APH(2″)-IVa, respectively, by tyrosine does not significantly change the antibiotic susceptibility profiles produced by the enzymes. In APH(2″)-IIa, M85Y substitution results in an ∼10-fold decrease in theKmvalue of GTP and an ∼320-fold increase in theKmvalue of ATP. In APH(2″)-IVa, F95Y substitution results in a modest decrease in theKmvalues of both GTP and ATP. Structural analysis indicates that in the APH(2″)-IIa M85Y mutant, tyrosine blocks access of ATP to the correct position in the binding site, while the larger nucleoside triphosphate (NTP)-binding pocket of the APH(2″)-IVa F95Y mutant allows the tyrosine to move away, thus giving access to the ATP-binding template.
