Figure 3.

Ribbon representation of the C-terminal domains of (a) ChpT and (b) DesK (Trajtenberg et al., 2010 ▶). DesK binds ATP in the ATP-binding pocket defined by the ATP lid (a loop between strand β3 and helix α5) and the central helix α4, while the γ-phosphate is exposed and can be attacked by the catalytic histidine of the DHp domain. In ChpT the ATP lid is substituted by two additional turns in the N-terminal part of helix α5. There is an additional short α-helix (α4′) between strand β5 and helix α5, which together with helix α5 closes the ATP-binding pocket.