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| Content Provider | PubMed Central |
|---|---|
| Author | Jeon, Jeong Ho Kim, Soo-jin Lee, Hyun Sook Cha, Sun-shin Lee, Jung Hun Yoon, Sang-hong Koo, Bon-sung Lee, Chang-muk Choi, Sang Ho Lee, Sang Hee Kang, Sung Gyun Lee, Jung-hyun |
| Copyright Year | 2011 |
| Abstract | It has been proposed that family VIII carboxylesterases and class C β-lactamases are phylogenetically related; however, none of carboxylesterases has been reported to hydrolyze β-lactam antibiotics except nitrocefin, a nonclinical chromogenic substrate. Here, we describe the first example of a novel carboxylesterase derived from a metagenome that is able to cleave the amide bond of various β-lactam substrates and the ester bond of p-nitrophenyl esters. A clone with lipolytic activity was selected by functional screening of a metagenomic library using tributyrin agar plates. The sequence analysis of the clone revealed the presence of an open reading frame (estU1) encoding a polypeptide of 426 amino acids, retaining an S-X-X-K motif that is conserved in class C β-lactamases and family VIII carboxylesterases. The gene was overexpressed in Escherichia coli, and the purified recombinant protein (EstU1) was further characterized. EstU1 showed esterase activity toward various chromogenic p-nitrophenyl esters. In addition, it exhibited hydrolytic activity toward nitrocefin, leading us to investigate whether EstU1 could hydrolyze β-lactam antibiotics. EstU1 was able to hydrolyze first-generation β-lactam antibiotics, such as cephalosporins, cephaloridine, cephalothin, and cefazolin. In a kinetic study, EstU1 showed a similar range of substrate affinities for both p-nitrophenyl butyrate and first-generation cephalosporins while the turnover efficiency for the latter was much lower. Furthermore, site-directed mutagenesis studies revealed that the catalytic triad of EstU1 plays a crucial role in hydrolyzing both ester bonds of p-nitrophenyl esters and amide bonds of the β-lactam ring of antibiotics, implicating the predicted catalytic triad of EstU1 in both activities. |
| Related Links | http://dx.doi.org/10.1128/aem.05363-11 |
| Ending Page | 7836 |
| Page Count | 7 |
| Starting Page | 7830 |
| File Format | |
| ISSN | 00992240 |
| e-ISSN | 10985336 |
| Journal | Applied and Environmental Microbiology |
| Issue Number | 21 |
| Volume Number | 77 |
| Language | English |
| Publisher | American Society for Microbiology |
| Publisher Date | 2011-11-01 |
| Access Restriction | Open |
| Rights Holder | American Society for Microbiology |
| Subject Keyword | Biotechnology Food Science Ecology Applied Microbiology and Biotechnology Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Ecology Food Science Applied Microbiology and Biotechnology Biotechnology |
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