title: DNA polymerase eta contributes to strand bias of mutations of A versus T in immunoglobulin genes.
abstract: DNA polymerase (pol) eta participates in hypermutation of A:T bases in Ig genes because humans deficient for the polymerase have fewer substitutions of these bases. To determine whether polymerase eta is also responsible for the well-known preference for mutations of A vs T on the nontranscribed strand, we sequenced variable regions from three patients with xeroderma pigmentosum variant (XP-V) disease, who lack polymerase eta. The frequency of mutations in the intronic region downstream of rearranged J(H)4 gene segments was similar between XP-V and control clones; however, there were fewer mutations of A:T bases and correspondingly more substitutions of C:G bases in the XP-V clones (p < 10(-7)). There was significantly less of a bias for mutations of A compared with T nucleotides in the XP-V clones compared with control clones, whereas the frequencies for mutations of C and G were identical in both groups. An analysis of mutations in the WA sequence motif suggests that polymerase eta generates more mutations of A than T on the nontranscribed strand. This in vivo data from polymerase eta-deficient B cells correlates well with the in vitro specificity of the enzyme. Because polymerase eta inserts more mutations opposite template T than template A, it would generate more substitutions of A on the newly synthesized strand.
authors.affiliation: Department of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA 31207, USA.
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Mayorov
authors.forename: Igor B
authors.initials: IB
authors.lastname: Rogozin
authors.forename: Linda R
authors.initials: LR
authors.lastname: Adkison
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Gearhart
mesh_terms: D000227:Adenine Nucleotides / Q000235:genetics*; D020816:Amino Acid Motifs / Q000235:genetics; D020029:Base Pairing / Q000235:genetics; D001483:Base Sequence; D002999:Clone Cells; D004252:DNA Mutational Analysis / Q000379:methods; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain / Q000235:genetics*; D005803:Genes, Immunoglobulin / Q000235:genetics*; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D027041:Somatic Hypermutation, Immunoglobulin; D013379:Substrate Specificity / Q000235:genetics; D013942:Thymine Nucleotides / Q000235:genetics*; D014158:Transcription, Genetic; D014983:Xeroderma Pigmentosum / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D000099270:Y-Family DNA Polymerases
chemical_list: D000227:Adenine Nucleotides; D004259:DNA-Directed DNA Polymerase; D007135:Immunoglobulin Variable Region; D013942:Thymine Nucleotides; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases