Unravelling the mechanism of RNA-polymerase forward motion by using mechanical force

• Published in: Physical review letters 2005-04, Vol.94 (12), p.128102.1-128102.4, Article 128102
• Main Authors: THOMEN, Philippe, LOPEZ, Pascal J, HESLOT, Francois
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - chemistry; Adenosine Triphosphate - metabolism; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Biotin - chemistry; Condensed Matter; Cytidine Triphosphate - chemistry; Cytidine Triphosphate - metabolism; DNA, Viral - chemistry; DNA, Viral - metabolism; DNA-Directed RNA Polymerases - chemistry; DNA-Directed RNA Polymerases - metabolism; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Guanosine Triphosphate - chemistry; Guanosine Triphosphate - metabolism; Kinetics; Other; Physics; Protein Conformation; Silicon Dioxide - chemistry; Streptavidin - chemistry; Thermodynamics; Uridine Triphosphate - chemistry; Uridine Triphosphate - metabolism; Viral Proteins - chemistry; Viral Proteins - metabolism
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.94.128102

Polymerases form a class of enzymes that act as molecular motors as they move along their nucleic acid substrate during catalysis, incorporating nucleotide triphosphates at the end of the growing chain and consuming chemical energy. A debated issue is how the enzyme converts chemical energy into motion [J. Gelles and R. Landick, Cell 93, 13 (1998)]. In a single molecule assay, we studied how an opposing mechanical force affects the translocation rate of T7 RNA polymerase. Our measurements show that force acts as a competitive inhibitor of nucleotide binding. This result is interpreted in the context of possible models, and with respect to published crystal structures of T7 RNA polymerase. The transcribing complex appears to utilize only a small fraction of the energy of hydrolysis to perform mechanical work, with the remainder being converted to heat.