A novel family VIII carboxylesterase hydrolysing third- and fourth-generation cephalosporins

• Published in: SpringerPlus 2016-04, Vol.5 (1), p.525-525, Article 525
• Main Authors: Jeon, Jeong Ho, Lee, Hyun Sook, Lee, Jung Hun, Koo, Bon-Sung, Lee, Chang-Muk, Lee, Sang Hee, Kang, Sung Gyun, Lee, Jung-Hyun
• Format: Article
• Language: English
• Subjects: Amino acids; Antibiotics; Biomedical and Life Sciences; Chromatography; E coli; Esters; Humanities and Social Sciences; multidisciplinary; Rhizosphere; Science; Science (multidisciplinary)
• ISSN: 2193-1801; 2193-1801
• DOI: 10.1186/s40064-016-2172-y

A metagenomic library was constructed from a soil sample of spindle tree-rhizosphere. From this library, one clone with esterase activity was selected. The sequence analysis revealed an open reading frame (EstSTR1) encoded protein of 390 amino acids. EstSTR1 is a family VIII carboxylesterase and retains the S-X-X-K motif conserved in both family VIII carboxylesterases and class C β-lactamases. The estSTR1 gene was overexpressed in E . coli and the recombinant protein was purified by purified by metal chelating affinity chromatography and size-exclusion chromatography. EstSTR1 hydrolysed p -nitrophenyl esters, exhibited the highest activity toward p -nitrophenyl butyrate. Furthermore, EstSTR1 could hydrolyse third- and fourth-generation cephalosporins (cefotaxime and cefepime) as well as first-generation cephalosporin (cephalothin). Site-directed mutagenesis studies revealed that a catalytic residue, Ser71, of EstSTR1 plays an essential role in hydrolysing both antibiotics and p -nitrophenyl esters. We demonstrate that a metagenome-derived carboxylesterase displays β-lactam-hydrolysing activities toward third- and fourth-generation cephalosporins.