Suoniemi_2002_Lait_82_81

An esterase gene, estA, from Propionibacterium freudenreichii ssp. shermanii was cloned in Eschericia coli. The clone, carrying a 3.1-kb insert, caused lipolysis on tributyrin agar during incubation at 4 C. The insert was sequenced and analyzed. It revealed two open reading frames, ORF1 and ORF2. ORF1 has a capability to code for a protein of 41.8 kg $\cdot$mol -1 (388 aa) and shares up to 38% identity with esterases or lipases from several bacteria. ORF2 encodes for a protein of 42.7 kg $\cdot$mol -1 (379 aa) and shares 62% identity with CaiA, a carnitine operon oxidoreductase with a CoA-binding site. The lipolytic enzyme coded by ORF1 degraded p-nitrophenyl butyrate, p-nitrophenyl caproate and tributyrin, but not long chain fatty acid substrates like p-nitrophenyl palmitate or triolein triglyceride. Based on the preference for short chain fatty acids, and the homology profiles, the ORF1 was named an esterase, EstA. The esterase degraded p-nitrophenyl butyrate between 4 C and 55 C, the optimum being at 37 C. The highest activity was detected at pH 8.