Ortholog of the polymerase theta helicase domain modulates DNA replication in Trypanosoma cruzi.

ABSTRACT: DNA polymerase theta (Pol?), a member of the DNA polymerase family A, exhibits a polymerase C-terminal domain, a central domain, and an N-terminal helicase domain. Pol? plays important roles in DNA repair via its polymerase domain, regulating genome integrity. In addition, in mammals, Pol? modulates origin firing timing and MCM helicase recruitment to chromatin. In contrast, as a model eukaryote, Trypanosoma cruzi exhibits two individual putative orthologs of Pol? in different genomic loci; one ortholog is homologous to the Pol? C-terminal polymerase domain, and the other is homologous to the Pol? helicase domain, called Pol?-polymerase and Pol?-helicase, respectively. A pull-down assay using the T. cruzi component of the prereplication complex Orc1/Cdc6 as bait captured Pol?-helicase from the nuclear extract. Orc1/Cdc6 and Pol?-helicase directly interacted, and Pol?-helicase presented DNA unwinding and ATPase activities. A T. cruzi strain overexpressing the Pol?-helicase domain exhibited a significantly decreased amount of DNA-bound MCM7 and impaired replication origin firing. Taken together, these data suggest that Pol?-helicase modulates DNA replication by directly interacting with Orc1/Cdc6, which reduces the binding of MCM7 to DNA and thereby impairs the firing of replication origins.

SUBMITTER: de Lima LP 

PROVIDER: S-EPMC6393585 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature