The FHA-containing protein GarA acts as a phosphorylation-dependent molecular switch in mycobacterial signaling

Abstract 

Fork-head associated (FHA) domains are widely found in bacteria, but their cellular functions remain unclear. Here, we focus on Mycobacterium tuberculosis GarA, an FHA-containing protein conserved in actinomycetes that is phosphorylated by different Ser/Thr protein kinases. Using various physicochemical approaches, we show that phosphorylation significantly stabilizes GarA, and that its FHA domain interacts strongly with the phosphorylated N-terminal extension. Altogether, our results indicate that phosphorylation triggers an intra-molecular protein closure, blocking the phosphothreonine-binding site and switching off the regulatory properties of GarA. The model can explain the reported functions of this mycobacterial protein as regulator of glycogen degradation and glutamate metabolism.

Structured summary:

MINT-6804218: GarA (uniprotkb:P64897) and GarA (uniprotkb:P64897) bind (MI:0407) by isothermal titration calorimetry (MI:0065)

Abbreviations: AUC, analytical ultracentrifugation, CD, circular dichroism, DLS, dynamic light scattering, DSC, differential scanning calorimetry, FHA, Fork-head associated, ITC, isothermal titration calorimetry, MALS, multi-angle light scattering, PAGE, polyacrylamide gel electrophoresis, SELDI-TOF, surface-enhanced laser desorption ionization time-of-flight.

Keywords: FHA domain, Signal transduction, Calorimetry, Physical chemistry, Mycobacterium tuberculosis