Diverse pathways for salicin utilization in Shigella sonnei and Escherichia coli carrying an impaired bgl operon

Desai, Stuti K. ; Nandimath, Krithi ; Mahadevan, S. (2010) Diverse pathways for salicin utilization in Shigella sonnei and Escherichia coli carrying an impaired bgl operon Archives of Microbiology, 192 (10). pp. 821-833. ISSN 0302-8933

Full text not available from this repository.

Official URL: http://www.springerlink.com/content/b7w76842106381...

Related URL: http://dx.doi.org/10.1007/s00203-010-0610-8

Abstract

Utilization of the aryl-β-glucosides salicin or arbutin in most wild-type strains of E. coli is achieved by a single-step mutational activation of the bgl operon. Shigella sonnei, a branch of the diverse E. coli strain tree, requires two sequential mutational steps for achieving salicin utilization as the bglB gene, encoding the phospho-β-glucosidase B, harbors an inactivating insertion. We show that in a natural isolate of S. sonnei, transcriptional activation of the gene βO1595, encoding a phospho-β-glucosidase, enables salicin utilization with the permease function being provided by the activated bgl operon. SSO1595 is absent in most commensal strains of E. coli, but is present in extra-intestinal pathogens as bgcA, a component of the bgc operon that enables β-glucoside utilization at low temperature. Salicin utilization in an E. coli bglB laboratory strain also requires a two-step activation process leading to expression of BglF, the PTS-associated permease encoded by the bgl operon and AscB, the phospho-β-glucosidase B encoded by the silent asc operon. BglF function is needed since AscF is unable to transport β-glucosides as it lacks the IIA domain involved in phopho-relay. Activation of the asc operon in the Sal+ mutant is by a promoter-up mutation and the activated operon is subject to induction. The pathway to achieve salicin utilization is therefore diverse in these two evolutionarily related organisms; however, both show cooperation between two silent genetic systems to achieve a new metabolic capability under selection.

Item Type:Article
Source:Copyright of this article belongs to Springer.
Keywords:Silent Genes; Beta-glucosides; Transcriptional Activation
ID Code:72344
Deposited On:23 Jun 2012 14:10
Last Modified:23 Jun 2012 14:10

Repository Staff Only: item control page