Molecular Modeling of the Catalytic Domain of CyaA Deepened the Knowledge of Its Functional Dynamics

Abstract

Although CyaA has been studied for over three decades and revealed itself to be a very good prototype for developing various biotechnological applications, only a little is known about its functional dynamics and about the conformational landscape of this protein. Molecular dynamics simulations helped to clarify the view on these points in the following way. First, the model of interaction between AC and calmodulin (CaM) has evolved from an interaction centered on the surface between C-CaM hydrophobic patch and the α helix H of AC, to a more balanced view, in which the C-terminal tail of AC along with the C-CaM Calcium loops play an important role. This role has been confirmed by the reduction of the affinity of AC for calmodulin in the presence of R338, D360 and N347 mutations. In addition, enhanced sampling studies have permitted to propose a representation of the conformational space for the isolated AC. It remains to refine this representation using structural low resolution information measured on the inactive state of AC. Finally, due to a virtual screening study on another adenyl cyclase from Bacillus anthracis, weak inhibitors of AC have been discovered.

Functional and structural insights into the multi-step activation and catalytic mechanism of bacterial ExoY nucleotidyl cyclase toxins bound to actin-profilin

“…In contrast to Vn-ExoY, CyaA or EF have the switch A already fully folded onto CaM in their nucleotide-free cofactor-bound state. Their C B /LID subdomain can however also adopt different positions in isolated CyaA (53) or between different crystal structures of CaM-bound EF (Fig. 6E, S10).…”

“…EF and CyaA, on the other hand, have a switch A that is already fully folded on CaM in their nucleotide-free, cofactor-bound state (Drum et al ., 2002; Guo et al ., 2005). However, their CB/LID subdomain can also adopt different positions in isolated CyaA (Malliavin, 2017) or between different crystal structures of CaM-bound EF (Fig. 6E, S8).…”

Structural Biology and Molecular Modeling to Analyze the Entry of Bacterial Toxins and Virulence Factors into Host Cells

“…Results obtained by molecular modeling on the catalytic domains of CyaA and EF have been reviewed in details in Refs. [68,69].…”

Revealing how an adenylate cyclase toxin uses bait and switch tactics in its activation

“…pertussis virulence factor. Targeted mutations reduce conformational stability and activation, providing further evidence that both dynamics and unique structural determinants are crucial regulators controlling CaM-dependent stimulation of CyaA-ACD [ 12 , 16 , 18 , 19 , 21 – 23 ]. Taken together, these findings imply that conformational switching, particularly in CyaA-ACD, is modulated in part by the formation of stabilizing interactions with CaM and is crucial to enzymatic activation.…”