Dataset Information

RNA-hydrolyzing activity of metallo-?-lactamase IMP-1.

ABSTRACT: Metallo-?-lactamases (MBLs) hydrolyze a wide range of ?-lactam antibiotics. While all MBLs share a common ??/??-fold, there are many other proteins with the same folding pattern that exhibit different enzymatic activities. These enzymes, together with MBLs, form the MBL superfamily. Thermotoga maritima tRNase Z, a tRNA 3' processing endoribonuclease of MBL-superfamily, and IMP-1, a clinically isolated MBL, showed a striking similarity in tertiary structure, despite low sequence homology. IMP-1 hydrolyzed both total cellular RNA and synthetic small unstructured RNAs. IMP-1 also hydrolyzed pre-tRNA, but its cleavage site was different from those of T. maritima tRNase Z and human tRNase Z long form, indicating a key difference in substrate recognition. Single-turnover kinetic assays suggested that substrate-binding affinity of T. maritima tRNase Z is much higher than that of IMP-1.

SUBMITTER: Kato Y

PROVIDER: S-EPMC7599082 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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RNA-hydrolyzing activity of metallo-β-lactamase IMP-1.

Kato Yoshiki Y Takahashi Masayuki M Seki Mineaki M Nashimoto Masayuki M Shimizu-Ibuka Akiko A

PloS one 20201030 10

Metallo-β-lactamases (MBLs) hydrolyze a wide range of β-lactam antibiotics. While all MBLs share a common αβ/βα-fold, there are many other proteins with the same folding pattern that exhibit different enzymatic activities. These enzymes, together with MBLs, form the MBL superfamily. Thermotoga maritima tRNase Z, a tRNA 3' processing endoribonuclease of MBL-superfamily, and IMP-1, a clinically isolated MBL, showed a striking similarity in tertiary structure, despite low sequence homology. IMP-1 h ...[more]

PMID: 33126240

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Project description:We recently detected a novel variant of an IMP-type metallo-β-lactamase gene (blaIMP-68) from meropenem-resistant but imipenem-susceptible Klebsiella pneumoniae TA6363 isolated in Tokyo, Japan. blaIMP-68 encodes a Ser262Gly point mutant of IMP-11, and transformation experiments showed that blaIMP-68 increased the MIC of carbapenems in recipient strains, whereas the MIC of imipenem was not greatly increased relative to that of other carbapenems, including meropenem. Kinetics experiments showed that IMP-68 imipenem-hydrolyzing activity was lower than that for other carbapenems, suggesting that the antimicrobial susceptibility profile of TA6363 originated from IMP-68 substrate specificity. Whole-genome sequencing showed that blaIMP-68 is harbored by the class 1 integron located on the IncL/M plasmid pTMTA63632 (88,953 bp), which was transferable via conjugation. The presence of plasmid-borne blaIMP-68 is notable, because it conferred antimicrobial resistance to carbapenems, except for imipenem, on Enterobacteriaceae and will likely affect treatment plans using antibacterial agents in clinical settings.IMPORTANCE IMP-type metallo-β-lactamases comprise one group of the "Big 5" carbapenemases. Here, a novel blaIMP-68 gene encoding IMP-68 (harboring a Ser262Gly point mutant of IMP-11) was discovered from meropenem-resistant but imipenem-susceptible Klebsiella pneumoniae TA6363. The Ser262Gly substitution was previously identified as important for substrate specificity according to a study of other IMP variants, including IMP-6. We confirmed that IMP-68 exhibited weaker imipenem-hydrolyzing activity than that for other carbapenems, demonstrating that the antimicrobial susceptibility profile of TA6363 originated from IMP-68 substrate specificity, with this likely to affect treatment strategies using antibacterial agents in clinical settings. Notably, the carbapenem resistance conferred by IMP-68 was undetectable based on the MIC of imipenem as a carbapenem representative, which demonstrates a comparable antimicrobial susceptibility profile to IMP-6-producing Enterobacteriaceae that previously spread in Japan due to lack of awareness of its existence.

Dataset Information

RNA-hydrolyzing activity of metallo-?-lactamase IMP-1.

Publications

RNA-hydrolyzing activity of metallo-β-lactamase IMP-1.

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