Practice question

Temporal shaping of extracellular cAMP waves depends on regulated degradation preventing uniform saturation. Secreted phosphodiesterase PdsA hydrolyzes cAMP to AMP in extracellular medium, creating troughs between pulses that allow receptor resensitization and directional sensing. PdsA is expressed during aggregation from cAMP-inducible promoter, membrane-associated, and inhibited by specific inhibitor PdiA. RegA degrades intracellular cAMP, ACA synthesizes cAMP, PiaA couples TOR complex 2 to ACA activation. Without PdsA, cAMP accumulates uniformly, abolishing gradient, cells fail to aggregate. Thus PdsA functions as essential extracellular terminator sculpting pulsatile dynamics that organize thousands of cells into streams.