Regulation of Sulfolobus acidocaldarius surface structures by the PP2A core interaction module

Protein phosphorylation serves as a key regulatory mechanism for organisms to adapt to altering environmental conditions. Sulfolobus acidocaldarius, a hyperthermophilic archaeon, possesses two phosphatases: the dual-specificity phosphatase PTP and the serine/threonine phosphatase PP2A. Previous research has linked PP2A to archaellum regulation, with its deletion leading to a hypermotile phenotype.

Under nutrient deprivation, PP2A associates with a stress regulatory module containing archaellum repressors ArnA and ArnB, the universal stress protein UspA, and the GPN-loop GTPase.

This study delved into the PP2A-associated proteins under regular growth conditions and subsequent UV-induced DNA damage. Using a PP2A strain with a genomically HA-tag, researchers identified a basal regulatory module composed of ArnA, ArnB, ArnE, and PTP. This network differed from the starvation-associated one previously described.

Moreover, several proteins integral to type IV pili biogenesis and regulation were observed co-purifying with PP2A. Functional examinations employing thermomicroscopy and electron microscopy showed that deleting {triangleup}pp2a, {triangleup}arnA, or {triangleup}arnB impairs Aap-pilus formation and twitching motility, indicating that the PP2A regulatory network governs both swimming and surface-associated motility.

Interestingly, the same network displayed a modulatory effect on UV-induced cell aggregation. The findings underscore PP2A's pivotal role in orchestrating various archaeal surface structures via phosphorylation-dependent signaling.