Regulatory divergence and functional diversification of a c-di-GMP-controlled sigma factor in Actinomycetota.

WhiG homologs in Actinomycetota have diverged into two clades, with one regulating flagellar biosynthesis and the other controlling sporulation and diverse processes, driven by c-di-GMP.

• Why it matters: Understanding how regulatory networks evolve in bacteria is essential for grasping their adaptation to environmental changes and functional diversity, especially in complex lineages like Actinomycetota.
• What they did: The study analyzed numerous WhiG homologs across Actinomycetota, revealing two distinct groups: one linked to flagellar regulation without RsiG control, and another regulated by RsiG via c-di-GMP, with bioinformatics predicting varied target functions.
• The result: This work uncovers a phylogenetic split in WhiG regulation, demonstrating its functional diversification in controlling motility, sporulation, antibiotic production, and c-di-GMP metabolism, advancing understanding of bacterial regulatory evolution.