Cloning and expression of an α-amylase encoding gene from the hyperthermophilic archaebacterium Thermococcus hydrothermalis and biochemical characterisation of the recombinant enzyme

Abstract

An alpha-amylase encoding gene from the extremely thermophilic Archaea Thermococcus hydrothermalis was cloned and expressed in Escherichia coli. The encoded alpha-amylase possesses molecular characteristics specific to the Archaea, especially from Pyrococcus species, with biochemical characteristics of the alpha-amylases from Thermococcus. The gene is 1374 bp long and encodes a protein of 457 amino acids composed of a 22 amino acid putative signal peptide and a 435 amino acid mature protein (calculated molecular mass 49236 Da). The T. hydrothermalis recombinant alpha-amylase is optimally active at 75-85 degrees C and at pH 5.0-5.5.