Team:Newcastle/SporulationTuning/NutrientStarvation

=Nutrient Starvation= A dramatic drop in the concentration of GTP and GDP correlates with the onset of sporulation, and inhibition of GMP synthesis by decoyinine treatment induces sporulation in the absence of nutrient starvation. CodY has recently been identified as the key sensor of guanine nucleotide levels. Disruption of the codY gene allows sporulation to occur in the presence of excess nutrients, and the ability of the CodY repressor to bind DNA correlates with the GTP concentration. As a consequence, when GTP levels drop upon entry into stationary phase, CodY-regulated genes are derepressed. Microchip array analysis has identified phrA, phrE, and kinB, all positive regulators of the phosphorelay, as targets of CodY repression. Therefore, one way that nutrient starvation is integrated into the decision to sporulate is transcriptional regulation of phosphorelay components via CodY. In addition, sporulation is also subject to catabolite repression and requires a functioning Krebs cycle, although the molecular basis of these dependencies is unknown.[1]