Regulation of L-arabinose transport in Salmonella typhimurium LT2.

The inducible L-arabinose transport system was characterized in Salmonella typhimurium LT2. Only one L-arabinose transport system with a Km of 2 X 10(-4) M was identified. The results suggested that araE may be the only gene which codes for L-arabinose transport activity under the conditions tested. An araE-lac fusion strain was used to study the induction of the araE gene. No araE expression was detected when the L-arabinose concentration was lower than 1 mM. The expression of araE reached a maximum in the presence of 50 mM L-arabinose, and was significantly reduced in the presence of 50 mM L-arabinose, and was significantly reduced in the presence of D-glucose. Expression of the araBAD and araE genes was coordinately regulated. The concentration of L-arabinose that allowed maximum araBAD gene expression was 50-fold lower in an araE+ strain compared to an araE strain.