Key role of barstar Cys‐40 residue in the mechanism of heat denaturation of bacterial ribonuclease complexes with barstar

Abstract

The mechanism by which barnase and binase are stabilized in their complexes with barstar and the role of the Cys-40 residue of barstar in that stabilization have been investigated by scanning microcalorimetry. Melting of ribonuclease complexes with barstar and its Cys-82-Ala mutant is described by two 2-state transitions. The lower-temperature one corresponds to barstar denaturation and the higher-temperature transition to ribonuclease melting. The barstar mutation Cys-40-Ala, which is within the principal barnase-binding region of barstar, simplifies the melting to a single 2-state transition. The presence of residue Cys-40 in barstar results in additional stabilization of ribonuclease in the complex.z 1999 Federation of European Biochemical Societies.

Brownian dynamics simulation of the competitive reactions: Binase dimerization and the association of binase and barstar

“…However, the activity of binase differs considerably from that of barnase [16,17]; the kinetic characteristics of the binase-barstar complex differ from the characteristics of barnase-barstar complex as well. It was demonstrated [18,19] that the association constant for the binase-barstar complex is by one order of magnitude lower than the constant for barnase inhibition by barstar.…”

Implicit solvent models for flexible protein–protein docking by molecular dynamics simulation

“…These proteins also vary in thermal stability 16, 17. For example, the melting temperature is 54.5°C for barnase,18 73.3°C for barstar,18 87.5°C for G B1 ,19 61.1°C for FBP28,20 and 43.6°C for YAP65 20. Then, to investigate the performance of the implicit solvent models in protein docking, MD simulations were conducted for the complexation of barnase with its inhibitor barstar and for the complexation of the PIN1 WW domain with a doubly phosphorylated peptide ligand (Tyr‐P.Ser‐Pro‐Thr‐P.Ser‐Pro‐Ser).…”