Biology's wires and motors : single-molecule mechanics of M13 bacteriophage and kinesin

[摘要] (cont.) Single-molecule assays centered around the ;;zinc fingered-phages;; are being developed to establish M13 as a standalone, single-molecule building block for achieving universal connectivity and for unlocking future studies on the nature of protein-DNA interactions. Kinesin is an ATPase that ;;walks;; processively along biofilament tracks to perform vital cellular processes. Whereas M13 mechanics were studied in the context of classical rod or polymer bending, our focus within kinesin mechanics is the molecular aspects of motility. While significant progress has been made in elucidating the broad features of the kinesin mechanochemical cycle, details of the force generation mechanism remain a mystery. Com3 bined efforts in molecular biology, optical trapping, and molecular simulation were employed to put forth a novel mechanism for the motor;;s power stroke, namely that it is produced when the conserved N-terminal cover strand forms a [beta]-sheet with the neck linker to yield the cover-neck bundle. In agreement with simulation, single-molecule motility data revealed impairment of the force-generating capacity of cover strand mutants, as measured by a reduction in stall force from the wild-type. Motility data also suggest that targeting forcegenerating elements, such as the cover strand, is a plausible strategy for designing biological motors with tunable motile properties, bringing us one step closer to a complete blueprint of kinesin;;s parts and their collective functioning.

[发布机构] Massachusetts Institute of Technology