title: Mechanical operation and intersubunit coordination of ring-shaped molecular motors: insights from single-molecule studies.
abstract: Ring NTPases represent a large and diverse group of proteins that couple their nucleotide hydrolysis activity to a mechanical task involving force generation and some type of transport process in the cell. Because of their shape, these enzymes often operate as gates that separate distinct cellular compartments to control and regulate the passage of chemical species across them. In this manner, ions and small molecules are moved across membranes, biopolymer substrates are segregated between cells or moved into confined spaces, double-stranded nucleic acids are separated into single strands to provide access to the genetic information, and polypeptides are unfolded and processed for recycling. Here we review the recent advances in the characterization of these motors using single-molecule manipulation and detection approaches. We describe the various mechanisms by which ring motors convert chemical energy to mechanical force or torque and coordinate the activities of individual subunits that constitute the ring. We also examine how single-molecule studies have contributed to a better understanding of the structural elements involved in motor-substrate interaction, mechanochemical coupling, and intersubunit coordination. Finally, we discuss how these molecular motors tailor their operation-often through regulation by other cofactors-to suit their unique biological functions.
authors.affiliation: Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; California Institute for Quantitative Biosciences, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California.
authors.forename: Shixin
authors.initials: S
authors.lastname: Liu
authors.affiliation: Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Physics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California.
authors.forename: Gheorghe
authors.initials: G
authors.lastname: Chistol
authors.affiliation: Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; California Institute for Quantitative Biosciences, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Physics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Molecular and Cell Biology, Department of Chemistry, Howard Hughes Medical Institute, and Kavli Energy NanoSciences Institute, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California. Electronic address: carlosjbustamante@gmail.com.
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D055595:Mechanical Phenomena; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043583:Nucleoside-Triphosphatase / Q000737:chemistry / Q000235:genetics; D021122:Protein Subunits / Q000378:metabolism*
chemical_list: D020409:Molecular Motor Proteins; D021122:Protein Subunits; D043583:Nucleoside-Triphosphatase