Identification, crystallization and preliminary X‐ray diffraction analysis of esterase A from Caulobacter crescentus CB15, a family VIII lipolytic enzyme

Publisher: John Wiley & Sons Inc

E-ISSN: 1744-3091|68|5|560-564

ISSN: 1744-3091

Source: Acta Crystallographica Section F, Vol.68, Iss.5, 2012-05, pp. : 560-564

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Abstract

The structures and functions of family VIII lipolytic enzymes, which have moderate sequence identity to class C β‐lactamases and penicillin‐binding proteins, are largely unknown. Here, the X‐ray crystallographic study of a family VIII esterase from Caulobacter crescentus CB15 (CcEstA) is described. Sequence analysis revealed that CcEstA has a conserved serine residue within the S‐X‐X‐K motif which acts as a catalytic nucleophile. Recombinant protein containing an N‐terminal His tag was expressed in Escherichia coli and purified to homogeneity. Functional studies showed that CcEstA acts on α‐ and β‐naphthyl acetate as substrates. In addition, it can catalyze the hydrolysis of ketoprofen ethyl ester, a highly useful product in industrial applications. CcEstA was crystallized using a solution consisting of 1.0 M potassium/sodium tartrate, 0.1 M imidazole pH 8.0, 0.2 M NaCl, and X‐ray diffraction data were collected to a resolution of 1.62 Å with an Rmerge of 9.4%. The crystals of CcEstA belonged to space group C2221, with unit‐cell parameters a = 172.23, b = 176.68, c = 47.93 Å. Structure determination is in progress.