Water skating: How polymerase sliding clamps move on DNA. (18th February 2021)

• Record Type: Journal Article
• Authors: Li, Huilin; Zheng, Fengwei; O'Donnell, Mike
• Is Part Of: FEBS journal. Volume 288:Number 24(2021)
• Page Start: 7256
• Page End: 7262
• Publication Date: 2021-02-18
• Subjects: cryo‐EM -- DNA polymerase -- PCNA -- sliding clamp; Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.15740
• Languages: English
• ISSNs: 1742-464X

Abstract

Abstract : Polymerase sliding clamps are ring‐shaped proteins that encircle duplex DNA and hold polymerases to DNA for high processivity during synthesis. The crystal structure of clamp‐DNA complex reveals that the DNA is highly tilted through the clamp with extensive interaction with the clamp inner surface. In contrast to the tilted clamp‐DNA interaction without DNA polymerases, recent structures of replicative polymerases of bacteria, eukaryotes, and archaea that are bound to the clamp and DNA show that the polymerase positions DNA straight through the clamp without direct protein‐DNA contacts. Instead, the clamp‐to‐DNA interaction is mediated by one or two layers of water. Hence, clamps 'water skate' on DNA during function with replicative polymerases from all domains of life, providing a nearly frictionless bearing for fast and processive DNA synthesis. Abstract : In the holoenzyme of the replicative DNA polymerase bound to DNA substrate and PCNA sliding clamp, the PCNA ring is held perpendicular to the dsDNA, such that the PCNA inner channel has no direct contact with DNA, enabling PCNA to 'water skate' on DNA unimpeded.