PDIP46 (DNA polymerase ? interacting protein 46) is an activating factor for human DNA polymerase ?.

ABSTRACT: PDIP46 (SKAR, POLDIP3) was discovered through its interaction with the p50 subunit of human DNA polymerase ? (Pol ?). Its functions in DNA replication are unknown. PDIP46 associates with Pol ? in cell extracts both by immunochemical and protein separation methods, as well as by ChIP analyses. PDIP46 also interacts with PCNA via multiple copies of a novel PCNA binding motif, the APIMs (AlkB homologue-2 PCNA-Interacting Motif). Sites for both p50 and PCNA binding were mapped to the N-terminal region containing the APIMs. Functional assays for the effects of PDIP46 on Pol ? activity on singly primed ssM13 DNA templates revealed that it is a novel and potent activator of Pol ?. The effects of PDIP46 on Pol ? in primer extension, strand displacement and synthesis through simple hairpin structures reveal a mechanism where PDIP46 facilitates Pol ?4 synthesis through regions of secondary structure on complex templates. In addition, evidence was obtained that PDIP46 is also capable of exerting its effects by a direct interaction with Pol ?, independent of PCNA. Mutation of the Pol ? and PCNA binding region resulted in a loss of PDIP46 functions. These studies support the view that PDIP46 is a novel accessory protein for Pol ? that is involved in cellular DNA replication. This raises the possibility that altered expression of PDIP46 or its mutation may affect Pol ? functions in vivo, and thereby be a nexus for altered genomic stability.

SUBMITTER: Wang X 

PROVIDER: S-EPMC4868757 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature