tailieunhanh - Báo cáo khoa học: Relation between domain evolution, specificity, and taxonomy of the a-amylase family members containing a C-terminal starch-binding domain

The a-amylase family (glycoside hydrolase family 13; GH 13) contains enzymes with approximately 30 specifi-cities. Six types of enzyme from the family can possess a C-terminal starch-binding domain (SBD): a-amylase, maltotetraohydrolase, maltopentaohydrolase, maltogenic a-amylase, acarviose transferase, and cyclodextrin glu-canotransferase (CGTase). Such enzymes are multidomain proteins and those that contain an SBD consist of four or five domains, the former enzymes being mainly hydrolases and the latter mainly transglycosidases. . | Eur. J. Biochem. 270 635-645 2003 FEBS 2003 doi Relation between domain evolution specificity and taxonomy of the a-amylase family members containing a C-terminal starch-binding domain Sitefan Janecek1 Birte Svensson2 and E. Ann MacGregor3 Institute of Molecular Biology Slovak Academy of Sciences Bratislava Slovakia department of Chemistry Carlsberg Laboratory Copenhagen Valby Denmark 3Department of Chemistry University of Manitoba Winnipeg Canada The a-amylase family glycoside hydrolase family 13 GH 13 contains enzymes with approximately 30 specificities. Six types of enzyme from the family can possess a C-terminal starch-binding domain SBD a-amylase maltotetraohydrolase maltopentaohydrolase maltogenic a-amylase acarviose transferase and cyclodextrin glu-canotransferase CGTase . Such enzymes are multidomain proteins and those that contain an SBD consist of four or five domains the former enzymes being mainly hydrolases and the latter mainly transglycosidases. The individual domains are labelled A the catalytic b a 8-barrel B C D and E SBD but D is lacking from the four-domain enzymes. Evolutionary trees were constructed for domains A B C and E and compared with the complete-sequence tree . The trees for domains A and B and the completesequence tree were very similar and contain two main groups of enzymes an amylase group and a CGTase group. The tree for domain C changed substantially the separation between the amylase and CGTase groups being shortened and a new border line being suggested to include the Klebsiella and Nostoc CGTases both four-domain proteins with the four-domain amylases. In the SBD tree the border between hydrolases mainly a-amylases and transglycosidases principally CGTases was not readily defined because maltogenic a-amylase acarviose transferase and the archaeal CGTase clustered together at a distance from the main CGTase cluster. Moreover the four-domain CGTases were rooted in the amylase group reflecting .