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

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 mot...

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Bibliographic Details
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
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Summary: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.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.94.128102