Abstract
DNA polymerase ν (POLN) is one of 16 DNA polymerases encoded in vertebrate genomes. It is important to determine its gene expression patterns, biological roles, and biochemical activities. By quantitative analysis of mRNA expression, we found that POLN from the zebrafish Danio rerio is expressed predominantly in testis. POLN is not detectably expressed in zebrafish embryos or in mouse embryonic stem cells. Consistent with this, injection of POLN-specific morpholino antisense oligonucleotides did not interfere with zebrafish embryonic development. Analysis of transcripts revealed that vertebrate POLN has an unusual gene expression arrangement, sharing a first exon with HAUS3, the gene encoding augmin-like complex subunit 3. HAUS3 is broadly expressed in embryonic and adult tissues, in contrast to POLN. Differential expression of POLN and HAUS3 appears to arise by alternate splicing of transcripts in mammalian cells and zebrafish. When POLN was ectopically overexpressed in human cells, it specifically coimmunoprecipitated with the homologous recombination factors BRCA1 and FANCJ, but not with previously suggested interaction partners (HELQ and members of the Fanconi anemia core complex). Purified zebrafish POLN protein is capable of thymine glycol bypass and strand displacement, with activity dependent on a basic amino acid residue known to stabilize the primer-template. These properties are conserved with the human enzyme. Although the physiological function of pol ν remains to be clarified, this study uncovers distinctive aspects of its expression control and evolutionarily conserved properties of this DNA polymerase.
Highlights
The biological function of DNA polymerase (POLN) is unknown
When POLN was ectopically overexpressed in human cells, it coimmunoprecipitated with the homologous recombination factors BRCA1 and FANCJ, but not with previously suggested interaction partners (HELQ and members of the Fanconi anemia core complex)
Standard curves for each gene were determined using the following plasmids: pDEST17 carrying cDNA coding 276 –1146 amino acids of D. rerio POLN (DrPOLN); full-length open reading frame (ORF) of DrHAUS3 cloned into pCR4; DrPOLQ clone; fulllength HsPOLN ORF cloned into pDEST17 [4]; HsPOLQ inserted into pFASTBac [11]; HsHAUS3 clone
Summary
Results: Vertebrate POLN genes are predominantly expressed in testis, share a first exon with HAUS3, and encode proteins with strand displacement and damage bypass activity. Significance: Conserved biochemical activities, expression patterns, and protein interactions suggest a restricted function of POLN in DNA processing. Bypass and strand displacement, with activity dependent on a basic amino acid residue known to stabilize the primer-template These properties are conserved with the human enzyme. Human DNA polymerase is encoded by the POLN gene. POLN and HAUS3 Share First Exon functions in homologous recombination reactions in chicken cells, leading to immunoglobulin V gene diversification by gene conversion [19]. We report the discovery of an unusual overlapping relationship between the POLN and HAUS3 genes in vertebrates These two genes share the same first exon, but they have very different expression patterns. We found that ectopically expressed POLN can interact with protein components of the DNA recombination machinery
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
