The connection between redox state and stationary phase entry in Caulobacter crescentus

Caulobacter is a Gram-negative bacteria taking a crescent shape. Some unique features of this organism are its dimorphic life cycle and its stalk possession. This bacterium is known to inhabit various environments, including those with poor nutrients. As an adaptive response to nutrient limitation, they elongate their stalk many times their body cell length to increase their body surface area for more nutrient uptake. Phosphate starvation is one condition that triggers stalk elongation in Caulobacter. However, as reported in a previous study, a mutation in a sugar-phosphate metabolic gene named manA caused a defect in stalk elongation regardless of the phosphate concentration. Furthermore, this mutant strain failed to go into stationary phase. To understand the connection between sugar-phosphate metabolism, stationary phase, and stalk elongation, we hypothesized a role for the SpdS/SpdR two-component system in sensing redox state via cysteine residues. We speculated that redox signaling regulates stationary phase genes to allow cells to undergo stationary phase successfully, enabling cells to elongate their stalks. To test this hypothesis, we constructed an spdS-KO strain and complemented it with cysteine single and double mutations. The results presented here disprove our hypothesis.M.S.Includes bibliographical reference