Differential Impact of Hexuronate Regulators ExuR and UxuR on the Escherichia coli Proteome

Abstract

ExuR and UxuR are paralogous proteins belonging to the GntR family of transcriptional regulators. Both are known to control hexuronic acid metabolism in a variety of Gammaproteobacteria but the relative impact of each of them is still unclear. Here, we apply 2D difference electrophoresis followed by mass-spectrometry to characterise the changes in the Escherichia coli proteome in response to a uxuR or exuR deletion. Our data clearly show that the effects are different: deletion of uxuR resulted in strongly enhanced expression of D-mannonate dehydratase UxuA and flagellar protein FliC, and in a reduced amount of outer membrane porin OmpF, while the absence of ExuR did not significantly alter the spectrum of detected proteins. Consequently, the physiological roles of proteins predicted as homologs seem to be far from identical. Effects of uxuR deletion were largely dependent on the cultivation conditions: during growth with glucose, UxuA and FliC were dramatically altered, while during growth with glucuronate, activation of both was not so prominent. During the growth with glucose, maximal activation was detected for FliC. This was further confirmed by expression analysis and physiological tests, thus suggesting the involvement of UxuR in the regulation of bacterial motility and biofilm formation.

Anti-biofilm activity of antimicrobial peptide CRAMP-34 by regulating 2-dehydro-3-deoxy-D-gluconate 5-dehydrogenase (KduD) of Escherichia coli

“…In addition, kduD is involved in the metabolism of galacturonic acid and glucuronic acid [38], and yqeF is involved in glucose metabolism [39]. Galacturonate, glucuronate, and gluconate play a critical role in the colonization of the mammalian large intestine [40], which is accompanied by the formation of bacterial bio lms that facilitate bacterial survival in harsh conditions [41]. Carbon sources serve as a source of nutrition and play a key role in bacterial adaptation to environmental conditions [41].…”

Outer Membrane Porins Contribute to Antimicrobial Resistance in Gram-Negative Bacteria

“…Pfs controls the transcription levels of OmpF and TolC in a negative and positive manner, respectively [ 139 ]. UxuR positively regulates OmpF expression with unknown mechanisms [ 84 ].…”

“…UxuR belongs to the GntR family of transcriptional regulators. A reduced amount of outer membrane porin OmpF was observed with the deletion of uxuR in E. coli , which suggests that UxuR regulates OmpF expression with unknown mechanisms [ 84 ]. Furthermore, our team discovered that the OmpF upstream promoter in C. werkmanii and its transcription could be combined with and negatively regulated by the maltose metabolic regulator MalT for the first time, but we did not investigate how OmpF mutants might react to various antibiotics [ 85 ].…”