Exposure to Glycolytic Carbon Sources Reveals a Novel Layer of Regulation for the MalT Regulon
Figure 2
Effect of carbon sources on viability, mal gene transcription and LamB expression. (a) Growth curves of ompR malT con mutants (strain AJW3098) grown in LB at 37°C without sugars (white diamonds) or supplemented with 22 mM glucose (black circles), maltose (medium gray diamonds), or sorbitol (light gray triangles). Values represent the mean of triplicates. Error bars are only shown when greater than the symbol. (b) Effect of glycolytic carbon sources on mal gene transcription. β-galactoside activity was determined in ompR malT con mutants (strain AJW3098) carrying a malEpΔ92-lac reporter fusion. Cells were grown in LB without carbon source or LB supplemented with 22 mM glucose, maltose, or sorbitol. Cells were harvested at an OD600 of 1. Values represent the mean of triplicates. (c) Effect of glycolytic carbon sources on LamB expression. Addition of carbon sources reduces LamB levels in ompR malT con mutants as determined by outer membrane preparations. Cells were grown in LB at 37°C and harvested during late exponential phase. Gels were stained with Coomassie brilliant blue. Lane 1, LB no additional carbon source (LB); lane 2, LB 22 mM glucose (LB glucose); lane 3, LB 22 mM maltose (LB maltose); lane 4, LB 22 mM sorbitol (LB sorbitol).
