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首页> 外文期刊>Microbiology and Immunology >Resistance to oxyimino beta-lactams due to a mutation of chromosomal beta-lactamase in Citrobacter freundii.
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Resistance to oxyimino beta-lactams due to a mutation of chromosomal beta-lactamase in Citrobacter freundii.

机译：由于弗氏柠檬酸杆菌中的染色体β-内酰胺酶突变而导致对羟亚氨基β-内酰胺的抗性。

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摘要

The duplicative mutation of an Ala-Val-Arg sequence at positions 208 to 210 in the loop structure of Enterobacter cloacae class C beta-lactamase caused substrate specificity extension to oxyimino beta-lactam antibiotics and this chromosomal mutation provided bacterial cells with high resistance to the beta-lactams (M. Nukaga et al, 1995, J. Biol. Chem. 270, 5729-5735). In order to confirm the universality of this phenomenon among other class C beta-lactamases, the duplicative mutation was applied to a class C beta-lactamase of Citrobacter freundii, which has 74% homology to the E. cloacae beta-lactamase amino acid sequence. The counterpart sequence to the Ala-Val-Arg of the E. cloacae enzyme in C. freundii beta-lactamase was identified to be Pro-Val-His. A Pro-Val-His sequence was inserted just after the native Pro-Val-His sequence at positions 208 to 210 in the C. freundii beta-lactamase. The resulting mutant of C. freundii beta-lactamase obtained a striking characteristic that we expected, showing substrate specificity extension to oxyimino beta-lactams. Nearly the same result was obtained with the insertion of an Ala-Val-Arg sequence after the native Pro-Val-His sequence. These results indicate that structural modification of this locus commonly induces modification of the substrate specificity to unfavorable substrates for many chromosomal class C beta-lactamases produced by gram-negative bacteria.
机译：阴沟肠杆菌C类β-内酰胺酶环结构中第208-210位的Ala-Val-Arg序列重复突变导致底物特异性扩展至氧亚氨基β-内酰胺类抗生素，这种染色体突变为细菌细胞提供了对这种细菌的高抗性β-内酰胺类（M.Nukaga等，1995，J.Biol.Chem.270，5729-5735）。为了确认该现象在其他C类β-内酰胺酶中的普遍性，将重复突变应用于弗氏柠檬酸杆菌的C类β-内酰胺酶，与阴沟肠杆菌β-内酰胺酶氨基酸序列具有74％的同源性。在弗氏梭菌β-内酰胺酶中阴沟肠杆菌酶Ala-Val-Arg的对应序列被鉴定为Pro-Val-His。将Pro-Val-His序列插入天然的Pro-Val-His序列之后，在弗氏梭菌β-内酰胺酶中的208至210位。所得的弗氏梭菌β-内酰胺酶突变体获得了我们预期的显着特征，显示了对氧亚氨基β-内酰胺的底物特异性延伸。在天然的Pro-Val-His序列之后插入Ala-Val-Arg序列，获得了几乎相同的结果。这些结果表明，对于由革兰氏阴性细菌产生的许多染色体C类β-内酰胺酶，该基因座的结构修饰通常诱导对不利的底物的底物特异性的修饰。

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