Absence of Nitrogen regulatory protein C affects the growth physiology of Salmonella Typhimurium by limiting glucose transport in the cell

Abstract

Abstract The NtrC is crucial for nitrogen regulation in S. Typhimurium. Under nitrogen limitation, NtrC activates the set of genes involved in ameliorating the slowing of growth. Schumacher et al (2013) demonstrated that ntrC mutation increases intracellular concentration of α-KG in the cell. Another report explained that α-KG inhibits (Enzyme 1) E1 protein. Taking this as a clue, we studied the glucose uptake of ΔntrC. Indeed, the ΔntrC was slow to uptake the glucose. It also showed smaller colonies and reduced cell size in an optimum glucose medium. The transcriptome studies in carbon and nitrogen rich medium, showed suppressed nitrogen transport and metabolism genes, and induction of maltose operon genes (encoding high affinity glucose transporters) in ΔntrC. Despite having suppressed nitrogen transport and metabolism genes in ΔntrC, there was no significant difference in nitrogen (ammonia) utilization between WT and ΔntrC. Hence, we show that, ΔntrC having hampered glucose transport but normal expression of glucose metabolism genes, exhibits glucose limiting growth (intracellular glucose deficiency). Consequently, generate hunger response (small cell size, slow growth rate and induced maltose operon genes) even during growth in glucose rich medium. Therefore, the current work adds evidence for intricate overlapping control of nitrogen and carbon metabolism.