ALPHA-AMYLASE GENE OF THERMOPHILIC STREPTOMYCES SP TO1 - NUCLEOTIDE-SEQUENCE, TRANSCRIPTIONAL AND AMINO-ACID-SEQUENCE ANALYSIS

The nucleotide sequence of a 1860-bp region encoding a thermostable cc -amylase of Streptomyces sp. T01 was determined. Frame analysis reveal ed the presence of a 1359-bp long open reading Frame (amy T01) encodin g a 453 amino acid protein with a deduced M-r of 49 kDa. Northern blot analysis revealed that amy T01 gene was expressed as approximately 1. 5-kbp monocistronic transcript in both SL1326/pLM1 and Streptomyces sp . T01 strains. Primer extension experiments indicated that the transcr iptional start site lies 30 bp upstream of the ATG start codon, and al lowed the identification of -35 (TTGCTG) and -10 (TACGCG) eubacterial- like promoter sequences. Amy T01 exhibits strong amino acid identities with those from other Streptomyces species with a maximum of 78% with S. thermoviolaceus alpha-amylase. Nevertheless, subtle amino acid cha nges such as the substitution of four conserved residues found at simi lar positions in other Streptomyces alpha-amylases by proline residues , and the substitution of three conserved hydrophilic amino acids by h ydrophobic ones in Amy T01 might account for the thermostable properti es of Amy T01. (C) 1998 Federation of European Microbiological Societi es. Published by Elsevier Science B.V.