Identification of an esterase from Bacillus acidocaldarius with sequence similarity to a hormone sensitive lipase subfamily

We purified an esterase from Bacillus acidocaldarius whose NH2-terminal sequence corresponds to an open reading frame (ORF) previously reported to show homology with the mammalian hormone sensitive lipase (HSL)-like subgroup of the esterase/lipase family. The enzyme displays esterase but not lipase activity. For this enzyme we predicted the alpha/beta-hydrolase topological fold common to several esterases and lipases and identified Set 155, Asp 252 and His 282 as the putative members of the catalytic triad.