Your browser version may not work well with NCBI's Web applications. More information here...
1: Mol Biol Evol. 1992 Jul;9(4):688-706.Click here to read Links

Nucleotide sequence, function, activation, and evolution of the cryptic asc operon of Escherichia coli K12.

Hall BG, Xu L.

Biology Department, University of Rochester, New York 14627.

The cryptic asc (previous called "SAC") operon of Escherichia coli K12 has been completely sequenced. It encodes a repressor (ascG); a PTS enzyme IIasc for the transport of arbutin, salicin, and cellobiose (ascF); and a phospho-beta-glucosidase that hydrolyzes the sugars which are phosphorylated during transport (ascB). ascG and ascFB are transcribed from divergent promoters. The cryptic operon is activated by the insertion of IS186 into the ascG (repressor) gene. The ascFB genes are paralogous to the cryptic bglFB genes, and ascG is paralogous to galR. The duplications that gave rise to these paralogous genes are estimated to have occurred approximately 320 Mya, a time that predates the divergence of E. coli and Salmonella typhimurium.

PMID: 1630307 [PubMed - indexed for MEDLINE]