Regulation of P suc , a sucrose-inducible promoter in Caulobacter crescentus.

In gram-negative bacteria, when nutrients are too large or too scarce to diffuse through outer membrane porins, TonB-dependent receptors (TBDRs) are utilized to actively translocate substrates across the outer membrane. Caulobacter crescentus is a gram-negative bacterium with a large set of TBDRs, many which have not been fully characterized. Previous studies identified SucA, a Caulobacter TBDR that transports sucrose. Our experiments further characterize the expression of sucA from the P _suc promoter and we identify P _suc as a tightly controlled, tunable promoter, responsive to changes in sucrose concentration with and without other carbon sources in the media.