scholarly journals DNA polymerases ν and θ are required for efficient immunoglobulin V gene diversification in chicken

2010 ◽  
Vol 189 (7) ◽  
pp. 1117-1127 ◽  
Author(s):  
Masaoki Kohzaki ◽  
Kana Nishihara ◽  
Kouji Hirota ◽  
Eiichiro Sonoda ◽  
Michio Yoshimura ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Gene Conversion ◽  
B Lymphocyte ◽  
Dna Polymerases ◽  
Point Mutations ◽  
Triple Mutant ◽  
Translesion Dna Synthesis ◽  
Gene Diversification ◽  
V Genes

The chicken DT40 B lymphocyte line diversifies its immunoglobulin (Ig) V genes through translesion DNA synthesis–dependent point mutations (Ig hypermutation) and homologous recombination (HR)–dependent Ig gene conversion. The error-prone biochemical characteristic of the A family DNA polymerases Polν and Polθ led us to explore the role of these polymerases in Ig gene diversification in DT40 cells. Disruption of both polymerases causes a significant decrease in Ig gene conversion events, although POLN−/−/POLQ−/− cells exhibit no prominent defect in HR-mediated DNA repair, as indicated by no increase in sensitivity to camptothecin. Polη has also been previously implicated in Ig gene conversion. We show that a POLH−/−/POLN−/−/POLQ−/− triple mutant displays no Ig gene conversion and reduced Ig hypermutation. Together, these data define a role for Polν and Polθ in recombination and suggest that the DNA synthesis associated with Ig gene conversion is accounted for by three specialized DNA polymerases.

scholarly journals Involvement of the essential yeast DNA polymerases in induced gene conversion.

1999 ◽  
Vol 46 (4) ◽  
pp. 862-872 ◽  
Author(s):  
A Hałas ◽  
A Ciesielski ◽  
J Zuk
Keyword(s):  
Dna Synthesis ◽  
Gene Conversion ◽  
Dna Polymerase ◽  
Dna Polymerases ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Polymerase Alpha ◽  
Genes Encoding ◽  
Mitotic Gene Conversion ◽  
Dna Strand

In the yeast Saccharomyces cerevisiae three different DNA polymerases alpha, delta and epsilon are involved in DNA replication. DNA polymerase alpha is responsible for initiation of DNA synthesis and polymerases delta and epsilon are required for elongation of DNA strand during replication. DNA polymerases delta and epsilon are also involved in DNA repair. In this work we studied the role of these three DNA polymerases in the process of recombinational synthesis. Using thermo-sensitive heteroallelic mutants in genes encoding DNA polymerases we studied their role in the process of induced gene conversion. Mutant strains were treated with mutagens, incubated under permissive or restrictive conditions and the numbers of convertants obtained were compared. A very high difference in the number of convertants between restrictive and permissive conditions was observed for polymerases alpha and delta, which suggests that these two polymerases play an important role in DNA synthesis during mitotic gene conversion. Marginal dependence of gene conversion on the activity of polymerase epsilon indicates that this DNA polymerase may be involved in this process but rather as an auxiliary enzyme.

scholarly journals Non-bulky Lesions in Human DNA: The Ways of Formation, Repair, and Replication

Acta Naturae ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 12-26 ◽  
Author(s):  
А. V. Ignatov ◽  
K. A. Bondarenko ◽  
A. V. Makarova
Keyword(s):  
Dna Damage ◽  
Dna Synthesis ◽  
High Efficiency ◽  
Dna Polymerases ◽  
Dna Lesions ◽  
Translesion Dna Synthesis ◽  
Human Dna ◽  
Mechanisms Of Formation ◽  
Bulky Dna Lesions

DNA damage is a major cause of replication interruption, mutations, and cell death. DNA damage is removed by several types of repair processes. The involvement of specialized DNA polymerases in replication provides an important mechanism that helps tolerate persistent DNA damage. Specialized DNA polymerases incorporate nucleotides opposite lesions with high efficiency but demonstrate low accuracy of DNA synthesis. In this review, we summarize the types and mechanisms of formation and repair of non-bulky DNA lesions, and we provide an overview of the role of specialized DNA polymerases in translesion DNA synthesis.

scholarly journals The SOS Error-Prone DNA Polymerase V Mutasome and β-Sliding Clamp Acting in Concert on Undamaged DNA and during Translesion Synthesis

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1083
Author(s):  
Adhirath Sikand ◽  
Malgorzata Jaszczur ◽  
Linda B. Bloom ◽  
Roger Woodgate ◽  
Michael M. Cox ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Pathogenic Bacteria ◽  
Fold Increase ◽  
Translesion Dna Synthesis ◽  
Sliding Clamp ◽  
Pol V ◽  
Dna Polymerase V ◽  
Acting In Concert

In the mid 1970s, Miroslav Radman and Evelyn Witkin proposed that Escherichia coli must encode a specialized error-prone DNA polymerase (pol) to account for the 100-fold increase in mutations accompanying induction of the SOS regulon. By the late 1980s, genetic studies showed that SOS mutagenesis required the presence of two “UV mutagenesis” genes, umuC and umuD, along with recA. Guided by the genetics, decades of biochemical studies have defined the predicted error-prone DNA polymerase as an activated complex of these three gene products, assembled as a mutasome, pol V Mut = UmuD’2C-RecA-ATP. Here, we explore the role of the β-sliding processivity clamp on the efficiency of pol V Mut-catalyzed DNA synthesis on undamaged DNA and during translesion DNA synthesis (TLS). Primer elongation efficiencies and TLS were strongly enhanced in the presence of β. The results suggest that β may have two stabilizing roles: its canonical role in tethering the pol at a primer-3’-terminus, and a possible second role in inhibiting pol V Mut’s ATPase to reduce the rate of mutasome-DNA dissociation. The identification of umuC, umuD, and recA homologs in numerous strains of pathogenic bacteria and plasmids will ensure the long and productive continuation of the genetic and biochemical journey initiated by Radman and Witkin.

scholarly journals RAD50 and RAD51 Define Two Pathways That Collaborate to Maintain Telomeres in the Absence of Telomerase

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Siyuan Le ◽  
J Kent Moore ◽  
James E Haber ◽  
Carol W Greider
Keyword(s):  
Cell Death ◽  
Telomere Length ◽  
Gene Conversion ◽  
De Novo ◽  
Dna Recombination ◽  
Telomere Maintenance ◽  
Triple Mutant ◽  
Yeast Telomerase ◽  
Telomere Lengthening

Abstract Telomere length is maintained by the de novo addition of telomere repeats by telomerase, yet recombination can elongate telomeres in the absence of telomerase. When the yeast telomerase RNA component, TLC1, is deleted, telomeres shorten and most cells die. However, gene conversion mediated by the RAD52 pathway allows telomere lengthening in rare survivor cells. To further investigate the role of recombination in telomere maintenance, we assayed telomere length and the ability to generate survivors in several isogenic DNA recombination mutants, including rad50, rad51, rad52, rad54, rad57, xrs2, and mre11. The rad51, rad52, rad54, and rad57 mutations increased the rate of cell death in the absence of TLC1. In contrast, although the rad50, xrs2, and mre11 strains initially had short telomeres, double mutants with tlc1 did not affect the rate of cell death, and survivors were generated at later times than tlc1 alone. While none of the double mutants of recombination genes and tlc1 (except rad52 tlc1) blocked the ability to generate survivors, a rad50 rad51 tlc1 triple mutant did not allow the generation of survivors. Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase.

scholarly journals Chronic Lymphocytic Leukemia B Cells Can Undergo Somatic Hypermutation and Intraclonal Immunoglobulin VHDJH Gene Diversification

2002 ◽  
Vol 196 (5) ◽  
pp. 629-639 ◽  
Author(s):  
Carmela Gurrieri ◽  
Peter McGuire ◽  
Hong Zan ◽  
Xiao-Jie Yan ◽  
Andrea Cerutti ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Lymphocyte ◽  
Somatic Hypermutation ◽  
Point Mutations ◽  
Single Strand Conformation Polymorphism ◽  
Lymphocytic Leukemia ◽  
Gene Diversification

Chronic lymphocytic leukemia (CLL) arises from the clonal expansion of a CD5+ B lymphocyte that is thought not to undergo intraclonal diversification. Using VHDJH cDNA single strand conformation polymorphism analyses, we detected intraclonal mobility variants in 11 of 18 CLL cases. cDNA sequence analyses indicated that these variants represented unique point-mutations (1–35/patient). In nine cases, these mutations were unique to individual submembers of the CLL clone, although in two cases they occurred in a large percentage of the clonal submembers and genealogical trees could be identified. The diversification process responsible for these changes led to single nucleotide changes that favored transitions over transversions, but did not target A nucleotides and did not have the replacement/silent nucleotide change characteristics of antigen-selected B cells. Intraclonal diversification did not correlate with the original mutational load of an individual CLL case in that diversification was as frequent in CLL cells with little or no somatic mutations as in those with considerable mutations. Finally, CLL B cells that did not exhibit intraclonal diversification in vivo could be induced to mutate their VHDJH genes in vitro after stimulation. These data indicate that a somatic mutation mechanism remains functional in CLL cells and could play a role in the evolution of the clone.

scholarly journals Role of the ubiquitin-binding domain of Polη in Rad18-independent translesion DNA synthesis in human cell extracts

2010 ◽  
Vol 38 (19) ◽  
pp. 6456-6465 ◽  
Author(s):  
Valérie Schmutz ◽  
Régine Janel-Bintz ◽  
Jérôme Wagner ◽  
Denis Biard ◽  
Naoko Shiomi ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Human Cell ◽  
Binding Domain ◽  
Translesion Dna Synthesis ◽  
Cell Extracts ◽  
Ubiquitin Binding ◽  
Ubiquitin Binding Domain ◽  
Translesion Dna

scholarly journals Trading Places: How Do DNA Polymerases Switch during Translesion DNA Synthesis?

2005 ◽  
Vol 19 (1) ◽  
pp. 143
Author(s):  
Errol C. Friedberg ◽  
Alan R. Lehmann ◽  
Robert P.P. Fuchs
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerases ◽  
Translesion Dna Synthesis ◽  
Translesion Dna

scholarly journals In VitroGap-directed Translesion DNA Synthesis of an Abasic Site Involving Human DNA Polymerases ϵ, λ, and β

2011 ◽  
Vol 286 (37) ◽  
pp. 32094-32104 ◽  
Author(s):  
Giuseppe Villani ◽  
Ulrich Hubscher ◽  
Nadege Gironis ◽  
Sinikka Parkkinen ◽  
Helmut Pospiech ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerases ◽  
Abasic Site ◽  
Translesion Dna Synthesis ◽  
Human Dna ◽  
Translesion Dna

Translesion DNA synthesis across double-base lesions derived from cross-links of an antitumor trinuclear platinum compound: primer extension, conformational and thermodynamic studies

Metallomics ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 132-144 ◽  
Author(s):  
O. Novakova ◽  
N. P. Farrell ◽  
V. Brabec
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerases ◽  
Primer Extension ◽  
Platinum Compound ◽  
Thermodynamic Studies ◽  
Translesion Dna Synthesis ◽  
Cross Links ◽  
Translesion Dna ◽  
Compound Primer ◽  
Double Base

The central linker of antitumor polynuclear Triplatin represents an important factor responsible for the lowered tolerance of its DNA double-base adducts by DNA polymerases.

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