FIG 3.

Developmental regulators control the levels of c-di-GMP synthesizing diguanylate cyclases (DGCs) in S. venezuelae. The BldD–c-di-GMP complex directly represses the expression of genes encoding proven (cdgB and cdgA) and predicted (sven4602 and sven5187) DGCs (4, 12, 49). This suggests that a negative feedback loop might be involved whereby c-di-GMP made by these DGCs binds to BldD, leading to repression of transcription. At the onset of sporulation, cdgB is also subject to repression by the developmental regulator WhiA (55). sven3999 encoding a putative DGC contains the rare TTA codon, suggesting that the BldA tRNA is required for its translation. Dashed lines indicate predicted wiring.