ISOLATION AND ANALYSIS OF GENES FOR AMYLOLYTIC ENZYMES OF THE HYPERTHERMOPHILIC BACTERIUM THERMOTOGA-MARITIMA

In addition to the previously identified 4-alpha-glucanotransferase ge ne mgtA and the alpha-amylase gene amyA of Thermotoga maritima strain MSB8 we have now isolated three further genes encoding amylolytic enzy mes from a gene library of this ancestral bacterium. The genes code fo r the extremely thermostable enzymes pullulanase (pulA), maltodextrin phosphorylase (agpA) and alpha-glucosidase (aglA) and have the potenti al to encode polypeptides with calculated molecular masses of 96.3 kDa , 96.1 kDa and 52.5 kDa, respectively. Comparative amino acid sequence analysis revealed that PulA and AgpA are clearly related to other kno wn enzymes with similar function. AglA, on the other hand, was not rel ated to other alpha-glucosidases but appears to belong to an enzyme fa mily containing alpha-galactosidases and 6-phospho-beta-glucosidases. Enzyme properties are reported which demonstrate the extreme thermosta bility of these T. maritima enzymes. (C) 1998 Published by Elsevier Sc ience B.V. All rights reserved.