Multisubunit Multiactive Site DNA Polymerase Complexes with Coordinated Activities

Abstract

Duplication of the genome requires efficient, rapid, and coordinated activities of many enzymes that interact within a larger replisome complex. However, whether those interactions are stable or stochastic is currently being tested. These enzymatic abilities include high processivities, fidelities and plasticities to ensure faithful genome maintenance in spite of many obstacles to DNA synthesis. Many multisubunit enzyme subcomplexes have been identified within the replisome and most stabilize enzyme complexes on DNA for continued and processive enzymatic action over long stretches of the genome. One of the most well characterized subcomplexes is the elongation complex minimally consisting of the DNA polymerase holoenzyme which includes accessory proteins known to stabilize the association of the polymerase and direct repeated catalysis.In particular, the stability of the DNA polymerase holoenzyme is sensitive to stable secondary DNA structures, protein/DNA complexes, and various DNA damage. High fidelity (HiFi) DNA polymerases in complex with their accessory proteins are responsible for the bulk of genome synthesis, however, most organisms encode multiple separate specialized DNA polymerases to aid in overcoming genomic obstacles with translesion synthesis (TLS). The presence of anywhere from 2 to 18 separate DNA polymerases (depending on the organism) all with identical specificities for a 3′‐OH primer/template DNA creates a complex multiequilibrium within a cell. Moreover, many of these DNA polymerases have been shown to directly or indirectly interact to enhance catalysis. For example, a HiFi trimeric DNA polymerase complex has increased kinetics and processivity explained through dynamic active site switching and exchange. Other direct DNA polymerase interactions allow for coordinated synthesis across DNA lesions through a concerted switch of active sites. Oligomeric DNA polymerase active site coordination will be shown using a variety of presteady‐state kinetic and thermodynamic assays. These and other DNA polymerase interactions and equilibria properties will be put into context and compared across different domains of life to illustrate DNA synthesis mechanisms that maintain a high degree of fidelity and plasticity in spite of a multitude of genomic obstacles.Support or Funding InformationBaylor UniversityAmerican Cancer Society (RSG‐11‐049‐01‐DMC)National Science Foundation (NSF1613534)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.