Analysis of the chiB gene of Serratia liquefaciens

A 4.6-kb EcoRI/BglII fragment of Serratia liquefaciens genomic DNA has been sequenced and within this fragment the chiB gene has been identified and c haracterized. The chiB ORF encodes a polypeptide with a deduced molecular m ass of 52-kDa and the translational product in vitro has chitinase, but not chitobiase activity. Alignment of the predicted Chib 499 amino acid sequen ce indicated a chitin-binding and a catalytic domain that shares homology t o the chitinase family 18 domain, to the Chib polypeptide of Serratia marce scens QMB1466 (93.6%), a human chitinase and several bacterial chitinases. This chiB gene sequence transcription/translation in Escherichia coli may b e blocked by a RNA folding mechanism thus controlling the chitin utilizatio n regulon in S, liquefaciens. (C) 2000 Elsevier Science B.V. All rights res erved.