Structural highlights
FunctionRNPA_BACSU RNaseP catalyzes the removal of the 5'-leader sequence from pre-tRNA to produce the mature 5'-terminus. It can also cleave other RNA substrates such as 4.5S RNA. The protein component plays an auxiliary but essential role in vivo by binding to the 5'-leader sequence and broadening the substrate specificity of the ribozyme. Publication Abstract from PubMedCoupled ligand binding and conformational change plays a central role in biological regulation. Ligands often regulate protein function by modulating conformational dynamics, yet the order in which binding and conformational change occurs are often hotly debated. Here we show that the "conformational selection versus induced fit" distinction on which this debate is based is a false dichotomy because the mechanism depends on ligand concentration. Using the binding of pyrophosphate (PPi) to Bacillus subtilis RNase P protein as a model, we show that coupled reactions are best understood as a change in flux between competing pathways with distinct orders of binding and conformational change. The degree of partitioning through each pathway depends strongly on PPi concentration, with ligand binding redistributing the conformational ensemble toward the folded state by both increasing folding rates and decreasing unfolding rates. These results indicate that ligand binding induces marked and varied changes in protein conformational dynamics, and that the order of binding and conformational change is ligand concentration dependent. Ligand Concentration Regulates the Pathways of Coupled Protein Folding and Binding.,Daniels KG, Tonthat NK, McClure DR, Chang YC, Liu X, Schumacher MA, Fierke CA, Schmidler SC, Oas TG J Am Chem Soc. 2014 Jan 9. PMID:24364358[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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