A DNA-centered explanation of the DNA polymerase translocation mechanism

• Published in: Scientific reports Vol. 7; no. 1; pp. 7566 - 8
• Main Author: Arias-Gonzalez, J. Ricardo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.08.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 631/57/2272; 631/92/173; Deoxyribonucleic acid; DNA; DNA - metabolism; DNA polymerase; DNA Replication; DNA-directed DNA polymerase; DNA-Directed DNA Polymerase - chemistry; DNA-Directed DNA Polymerase - metabolism; Energy consumption; Fidelity; Humanities and Social Sciences; Motion; multidisciplinary; Ribonucleic acid; RNA; Science; Science (multidisciplinary); Thermodynamics; Transcription; Translocation
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-08038-2

DNA polymerase couples chemical energy to translocation along a DNA template with a specific directionality while it replicates genetic information. According to single-molecule manipulation experiments, the polymerase-DNA complex can work against loads greater than 50 pN. It is not known, on the one hand, how chemical energy is transduced into mechanical motion, accounting for such large forces on sub-nanometer steps, and, on the other hand, how energy consumption in fidelity maintenance integrates in this non-equilibrium cycle. Here, we propose a translocation mechanism that points to the flexibility of the DNA, including its overstretching transition, as the principal responsible for the DNA polymerase ratcheting motion. By using thermodynamic analyses, we then find that an external load hardly affects the fidelity of the copying process and, consequently, that translocation and fidelity maintenance are loosely coupled processes. The proposed translocation mechanism is compatible with single-molecule experiments, structural data and stereochemical details of the DNA-protein complex that is formed during replication, and may be extended to RNA transcription.