Dataset Information

Elevating NagZ Improves Resistance to ?-Lactam Antibiotics via Promoting AmpC ?-Lactamase in Enterobacter cloacae.

ABSTRACT: Enterobacter cloacae complex (ECC), one of the most common opportunistic pathogens causing multiple infections in human, is resistant to ?-lactam antibiotics mainly due to its highly expressed chromosomal AmpC ?-lactamase. It seems that regulation of chromosomal AmpC ?-lactamase is associated with peptidoglycan recycling. However, underlying mechanisms are still poorly understood. In this study, we confirmed that NagZ, a glycoside hydrolase participating in peptidoglycan recycling in Gram-negative bacteria, plays a crucial role in developing resistance of E. cloacae (EC) to ?-lactam antibiotics by promoting expression of chromosomal AmpC ?-lactamase. Our data shows that NagZ was significantly up-regulated in resistant EC (resistant to at least one type of the third or fourth generation cephalosporins) compared to susceptible EC (susceptible to all types of the third and fourth generation cephalosporins). Similarly, the expression and ?-lactamase activity of ampC were markedly enhanced in resistant EC. Moreover, ectopic expression of nagZ enhanced ampC expression and resistance to ?-lactam antibiotics in susceptible EC. To further understand functions of NagZ in ?-lactam resistance, nagZ-knockout EC model (?nagZ EC) was constructed by homologous recombination. Conversely, ampC mRNA and protein levels were down-regulated, and resistance to ?-lactam antibiotics was attenuated in ?nagZ EC, while specific complementation of nagZ was able to rescue ampC expression and resistance in ?nagZ EC. More interestingly, NagZ and its hydrolyzates 1,6-anhydromuropeptides (anhMurNAc) could induce the expression of other target genes of AmpR (a global transcriptional factor), which suggested that the promotion of AmpC by NagZ is mediated AmpR activated by anhMurNAc in EC. In conclusion, these findings provide new elements for a better understanding of resistance in EC, which is crucial for the identification of novel potential drug targets.

SUBMITTER: Yang X

PROVIDER: S-EPMC7672007 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Elevating NagZ Improves Resistance to β-Lactam Antibiotics via Promoting AmpC β-Lactamase in <i>Enterobacter cloacae</i>.

Yang Xianggui X Zeng Jun J Zhou Qin Q Yu Xuejing X Zhong Yuanxiu Y Wang Fuying F Du Hongfei H Nie Fang F Pang Xueli X Wang Dan D Fan Yingzi Y Bai Tingting T Xu Ying Y

Frontiers in microbiology 20201104

<i>Enterobacter cloacae</i> complex (ECC), one of the most common opportunistic pathogens causing multiple infections in human, is resistant to β-lactam antibiotics mainly due to its highly expressed chromosomal AmpC β-lactamase. It seems that regulation of chromosomal AmpC β-lactamase is associated with peptidoglycan recycling. However, underlying mechanisms are still poorly understood. In this study, we confirmed that NagZ, a glycoside hydrolase participating in peptidoglycan recycling in Gram ...[more]

PMID: 33250874

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Project description:The worldwide dissemination of CTX-M type β-lactamases is a threat to human health. Previously, we have reported the spread of bla(CTX-M-15) gene in different clinical strains of Enterobacteriaceae from the hospital settings of Aligarh in north India. In view of the varying resistance pattern against cephalosporins and other β-lactam antibiotics, we intended to understand the correlation between MICs and catalytic activity of CTX-M-15. In this study, steady-state kinetic parameters and MICs were determined on E. coli DH5α transformed with bla(CTX-M-15) gene that was cloned from Enterobacter cloacae (EC-15) strain of clinical background. The effect of conventional β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam) on CTX-M-15 was also studied. We have found that tazobactam is the best among these inhibitors against CTX-M-15. The inhibition characteristic of tazobactam is defined by its very low IC(50) value (6 nM), high affinity (K(i) = 0.017 µM) and better acylation efficiency (k(+2)/K' = 0.44 µM(-1)s(-1)). It forms an acyl-enzyme covalent complex, which is quite stable (k(+3) = 0.0057 s(-1)). Since increasing resistance has been reported against conventional β-lactam antibiotic-inhibitor combinations, we aspire to design a non-β-lactam core containing β-lactamase inhibitor. For this, we screened ZINC database and performed molecular docking to identify a potential non-β-lactam based inhibitor (ZINC03787097). The MICs of cephalosporin antibiotics in combination with this inhibitor gave promising results. Steady-state kinetics and molecular docking studies showed that ZINC03787097 is a reversible inhibitor which binds non-covalently to the active site of the enzyme through hydrogen bonds and hydrophobic interactions. Though, it's IC(50) (180 nM) is much higher than tazobactam, it has good affinity for CTX-M-15 (K(i) = 0.388 µM). This study concludes that ZINC03787097 compound can be used as seed molecule to design more efficient non-β-lactam containing β-lactamase inhibitor that could evade pre-existing bacterial resistance mechanisms.

Dataset Information

Elevating NagZ Improves Resistance to ?-Lactam Antibiotics via Promoting AmpC ?-Lactamase in Enterobacter cloacae.

Publications

Elevating NagZ Improves Resistance to β-Lactam Antibiotics via Promoting AmpC β-Lactamase in <i>Enterobacter cloacae</i>.

Similar Datasets

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