Sequence Analysis and Characterisation of a Novel Pectin Acetyl Esterase from Bacillus Subtilis

Abstract

A recombinant pectin acetyl esterase (YxiM) from Bacillus subtilis was characterised and the enzymatic properties compared to previously characterised pectin acetyl esterases (PAE’s). The YxiM protein had a pH optimum of 8.0 and was stable above pH 4.O. The enzyme released acetate from pectin isolated from different sources and from various synthetic compounds. In addition, YxiM showed a preference for acetylated tobacco homogalacturonan oligomers. Determination of the kinetic constants of YxiM indicated that the enzyme had a higher affinity to acetylated substrates, but a lower specific activity towards these substrates than PaeY from Erwinia chrysanthemi. Pre-treatment of sugar beet pectin with pectin methyl esterase (PME) from Aspergillus aculeatus increased the ability of YxiM to release acetate and similarly, pre-treatment with YxiM increased the ability of PME to release methanol. This demonstrates that YxiM acts in synergy with PME on the modification of plant cell wall pectin.