AMLC, ANOTHER AMYLOLYTIC GENE MAPS CLOSE TO THE AMLB LOCUS IN STREPTOMYCES-LIVIDANS TK24

The region located upstream of the alpha-amylase gene (amlB) of Strept omyces lividans TK24 (Yin et al., 1997) contains a 2978-bp-long ORF di vergent from amlB, and designated amlC. amlC Encodes a 993 amino acid (aa) protein with a calculated molecular weight of 107.054 kDa. On the basis of sequence similarity as well, as enzymatic activity, AmlC is likely to belong to the 1,4-alpha-D-glucan glucanohydrolase family. am lC is transcribed as a unique 3 kb leaderless monocistronic mRNA. Prim er extension experiments allowed the identification of promoter sequen ces that do not resemble the typical eubacterial promoter sequences. a mlC was successfully disrupted and was mapped at approx. 700 kb from a chromosomal end of S. lividans TK24, 100 kb on the right of the ampli fiable unit AUD1 (Volff et al., 1996). Nevertheless, amlC disruption s eemed to be accompanied by extensive rearrangements of the 2500-kb Dra I-II fragment of the chromosome. (C) 1998 Elsevier Science B.V. All ri ghts reserved.