Adapting to nutritional downshifts is crucial for the survival of Vibrio cholerae. CgtA, a 50S ribosome-associated essential GTPase, is a bonafide stringent response protein. CgtA, in association with SpoT, modulates the intracellular (p)ppGpp alarmone levels in a nutrient-rich environment. We studied the influence of CgtA during the growth of V. cholerae in a minimal medium in contrast to its pre-defined role in a nutrient-rich medium. Here, we show the pleiotropic effects of CgtA on growth, viability, motility, morphology, and persister phenotype of a V. cholerae strain where the full-length wildtype (Wt) cgtA was deleted. An in-frame deletion of the 52 amino acids long unstructured C-terminal domain of the CgtA GTPase defined its in vivo functionality. Transcriptomics and proteomic analyses revealed that loss of CgtA significantly altered a large number of genes and proteins respectively. A sustained mRNA expression pattern of CgtA is observed in a minimal medium. Whereas, in nutrient-rich LB medium, intermittent expression of cgtA is observed with the highest expression during the late-logarithmic to early-stationary phase. We propose that minimal media-associated nutrient stress coupled to cgtA depletion aggravates the intracellular stress in V. cholerae, leading to abnormal protein synthesis, altered DNA replication, and transcriptional machinery, negatively affecting cellular energy metabolism and many vital processes. This study suggests that the nutrient-media-dependent controlled expression of CgtA is a mechanism by which V. cholerae can remodel its transcriptome and proteome. Our study reveals an alternative facet of the survival of V. cholerae during nutritional downshift and the consequences concomitantly with cgtA knockdown as evident from the complex altered regulatory network.
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