CONFORMATIONAL FLUCTUATIONS RELATED TO CATALYSIS IN HUMAN RIBONUCLEASE SUPERFAMILY

Abstract

The high catalytic efficiency of enzymes is a result of structural and dynamical effects. The role of enzyme structure in catalysis has been understood for some time. The enzymes of the ribonuclease A (RNase) family possess identical or similar active site residues and conserved fold architecture. However, their catalytic efficiency differs by 105–106 fold. Moreover, the rate of dynamics among the RNases ranges from microsecond to second time‐scale, a factor 106 difference. Recent investigations provide insights into the role of conformational fluctuations (dynamics at multiple time‐scales) in enzyme catalysis. The fluctuations allow enzymes to sample inter‐converting conformations (called as conformational sub‐states). These conformational sub‐states are proposed to contain features that can promote the function of an enzyme. Therefore, correlating the role of time dependent dynamics in sampling functionally relevant conformational sub‐states would enable a better understanding of the catalytic mechanism of the various RNases. NMR relaxation dispersion experiments show distinct patterns of dynamical variations among the RNases clustered into sub‐families having different biological functions within the same fold. A combination of theoretical modeling, computer simulations and higher order statistics has enabled the identification of conformational sub‐states that regulate the mechanism substrate binding, catalysis and product removal in representative members of each sub‐family found in the human genome. The representative members of each sub‐family have diverse conformational sub‐states associated with each step of the catalytic cycle suggesting a possible correlation between dynamics and function.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.