Title: The salCAB operon of Azospirillum irakense, required for growth on salicin, is repressed by SalR, a transcriptional regulator that belongs to the LacI/GalR family
Authors: Somers, Ellen ×
Keijers, V.
Ptacek, Dave
Ottoy, M.H.
Srinivasan, M.
Vanderleyden, Jozef
Faure, D. #
Issue Date: 2000
Publisher: Springer-verlag
Series Title: Molecular and general genetics vol:263 issue:6 pages:1038-1046
Abstract: The salAB genes of Azospirillum irakense KBC1, which encode two aryl-beta-glucosidases, are required for growth on salicin. In the 4-kb region upstream of the salAB genes, two additional genes, salC and salR, were identified. SalC shows characteristics of the outer membrane receptors in the FepA/FhuA family. The salCAB genes are transcribed as a polycistronic mRNA. The salR gene encodes a protein homologous to the LacI/GalR family of transcriptional repressors. Expression of the sal operon, measured by means of a salC-gusA translational fusion in A. irakense KBC1, requires the presence of aryl-beta-glucosides such as arbutin and salicin. Expression is markedly enhanced when a simple carbon source, like glucose, cellobiose or malate, is added to the medium. In a salR mutant, expression of the salC-gusA fusion does not require an aryl-beta-glucoside inducer. Expression of a sal-R-gusA fusion is constitutive. The product of arbutin hydrolysis (hydroquinone) partly inhibits the expression of a salC-gusA fusion in arbutin- or salicin-containing minimal medium. This effect is independent of SalR. Salicylalcohol, the hydrolysis product of salicin, also partly inhibits salC expression in a SalR-independent fashion, but only in salicin-containing minimal medium.
ISSN: 0026-8925
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre of Microbial and Plant Genetics
× corresponding author
# (joint) last author

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