Novel phosphotransferase genes revealed by bacterial genome sequencing: a gene cluster encoding a putative N-acetylgalactosamine metabolic pathway in Escherichia coli

Department of Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA ABSTRACT Summary: We have analysed a gene cluster in the 67.4-76.0 min region of the Escherichia coli chromosome, revealed by recent systematic genome sequencing. The genes within this cluster include: (1) five genes encoding homologues of the E. coli mannose permease of the phosphotransferase system (IIB, IIB', IIC, IIC' and IID); (2) genes encoding a putative N -acetylgalactosamine 6-phosphate metabolic pathway including (a) a deacetylase, (b) an isomerizing deaminase, (c) a putative carbohydrate kinase, and (d) an aldolase; and (3) a transcriptional regulatory protein homologous to members of the DeoR family. Evidence is presented suggesting that the aldolase-encoding gene within this cluster is the previously designated kba gene that encodes tagatose-1,6-bisphosphate aldolase. These proteins and a novel IIA Man -like protein encoded in the 2.4-4.1 min region are characterized with respect to their sequence similarities and phylogenetic relationships with other homologous proteins. A pathway for the metabolism of N -acetylgalactosamine biochemically similar to that for the metabolism of N -acetylglucosamine is proposed. Author for correspondence: Milton H. Saier, Jr. Tel: +1619 534 4084. Fax: +1619 534 7108. e-mail: msaier@ucsd.edu Keywords: Escherichia coli genome, phosphotransferase system, sugar transport, N -acetylgalacrosamine, aldolases