scholarly journals Compensation for the absence of the catalytically active half of DNA polymerase ε in yeast by positively selected mutations in CDC28 gene

2020 ◽  
Author(s):  
Elena I. Stepchenkova ◽  
Anna S. Zhuk ◽  
Jian Cui ◽  
Elena R. Tarakhovskaya ◽  
Stephanie R. Barbari ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Polymerase ◽  
Chromosomal Instability ◽  
Dna Polymerases ◽  
Terminal Part ◽  
Spontaneous Mutagenesis ◽  
Cyclin Dependent Kinases ◽  
Catalytically Active ◽  
Leading Strand ◽  
Selection For

AbstractDNA polymerase ε (pol ε) participates in the leading DNA strand synthesis in eukaryotes. The catalytic subunit of this enzyme, Pol2, is a fusion of two ancestral B-family DNA polymerases. Paradoxically, the catalytically active N-terminal pol is dispensable, and an inactive C-terminal pol is essential for yeast cell viability. Despite extensive studies of strains without the active N-terminal half (mutation pol2-16), it is still unclear how they survive and what is the mechanism of rapid recovery of initially miserably growing cells. The reason for the slow progress is in the difficultly of obtaining strains with the defect. We designed a robust method for constructing mutants with only the C-terminal part of Pol2 using allele pol2rc-ΔN with optimized codon usage. Colonies bearing pol2rc-ΔN appear three times sooner than colonies of pol2-16 but exhibit similar growth defects: sensitivity to hydroxyurea, chromosomal instability, and an elevated level of spontaneous mutagenesis. UV-induced mutagenesis is partially affected; it is lower only at high doses in some reporters. The analysis of the genomes of pol2rc-ΔN isolates revealed the prevalence of nonsynonymous mutations suggesting that the growth recovery was a result of positive selection for better growth fueled by variants produced by the elevated mutation rate. Mutations in the CDC28 gene, the primary regulator of the cell cycle, were repeatedly found in independent clones. Genetic analysis established that cdc28 alleles single-handedly improve the growth of pol2rc-ΔN strains and suppress sensitivity hydroxyurea. The affected amino acids are located on the Cdc28 molecule’s two surfaces that mediate contacts with cyclins or kinase subunits. Our work establishes the significance of the CDC28 gene for the resilience of replication and predicts that changes in mammalian homologs of cyclin-dependent kinases may play a role in remastering replication to compensate for the defects in the leading strand synthesis by the dedicated polymerase.Author SummaryThe catalytic subunit of the leading strand DNA polymerase ε, Pol2, consists of two halves made of two different ancestral B-family DNA polymerases. Counterintuitively, the catalytically active N-terminal half is dispensable while the inactive C-terminal part is required for viability. The corresponding strains show a severe growth defect, sensitivity to replication inhibitors, chromosomal instability, and elevated spontaneous mutagenesis. Intriguingly, the slow-growing mutant strains rapidly produced fast-growing clones. We discovered that the adaptation to the loss of the catalytic N-terminal part of Pol2 occurs during evolution by positive selection for a better growth fueled by variants produced by elevated mutation rates. Mutations in the cell cycle-dependent kinase gene, CDC28, can single-handedly improve the growth of strains lacking the N-terminal part of Pol2. Our study predicts that changes in mammalian homologs of cyclin-dependent kinases may play a role in response to the defects of active leading strand polymerase.

Compensation for the absence of the catalytically active half of DNA polymerase ε in yeast by positively selected mutations in CDC28

Genetics ◽  
2021 ◽  
Author(s):  
Elena I Stepchenkova ◽  
Anna S Zhuk ◽  
Jian Cui ◽  
Elena R Tarakhovskaya ◽  
Stephanie R Barbari ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Dna Sequences ◽  
Dna Polymerases ◽  
Mutation Rates ◽  
Terminal Part ◽  
Kinase Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Catalytically Active ◽  
Leading Strand ◽  
Cycle Dependent

Abstract Current eukaryotic replication models postulate that leading and lagging DNA strands are replicated predominantly by dedicated DNA polymerases. The catalytic subunit of the leading strand DNA polymerase ε, Pol2, consists of two halves made of two different ancestral B-family DNA polymerases. Counterintuitively, the catalytically active N-terminal half is dispensable, while the inactive C-terminal part is required for viability. Despite extensive studies of yeast Saccharomyces cerevisiae strains lacking the active N-terminal half, it is still unclear how these strains survive and recover. We designed a robust method for constructing mutants with only the C-terminal part of Pol2. Strains without the active polymerase part show severe growth defects, sensitivity to replication inhibitors, chromosomal instability, and elevated spontaneous mutagenesis. Intriguingly, the slow-growing mutant strains rapidly accumulate fast-growing clones. Analysis of genomic DNA sequences of these clones revealed that the adaptation to the loss of the catalytic N-terminal part of Pol2 occurs by a positive selection of mutants with improved growth. Elevated mutation rates help generate sufficient numbers of these variants. Single nucleotide changes in the cell cycle-dependent kinase gene, CDC28, improve the growth of strains lacking the N-terminal part of Pol2, and rescue their sensitivity to replication inhibitors and, in parallel, lower mutation rates. Our study predicts that changes in mammalian homologs of cyclin-dependent kinases may contribute to cellular responses to the leading strand polymerase defects.

scholarly journals Ribonucleotide incorporation characteristics around yeast autonomously replicating sequences reveal the labor division of replicative DNA polymerases

2020 ◽  
Author(s):  
Penghao Xu ◽  
Francesca Storici
Keyword(s):  
Dna Polymerase ◽  
Genome Instability ◽  
Dna Polymerases ◽  
Yeast Cells ◽  
Yeast Genome ◽  
Wild Type ◽  
Specific Sequence ◽  
Leading Strand ◽  
Mapping Techniques ◽  
Lagging Strand

ABSTRACTRibonucleoside monophosphate (rNMP) incorporation in DNA is a natural and prominent phenomenon resulting in DNA structural change and genome instability. While DNA polymerases have different rNMP incorporation rates, little is known whether these enzymes incorporate rNMPs following specific sequence patterns. In this study, we analyzed a series of rNMP incorporation datasets, generated from three rNMP mapping techniques, and obtained from Saccharomyces cerevisiae cells expressing wild-type or mutant replicative DNA polymerase and ribonuclease H2 genes. We performed computational analyses of rNMP sites around early and late firing autonomously replicating sequences (ARS’s) of the yeast genome, from which bidirectional, leading and lagging DNA synthesis starts. We find the preference of rNMP incorporation on the leading strand in wild-type DNA polymerase yeast cells. The leading/lagging-strand ratio of rNMP incorporation changes dramatically within 500 nt from ARS’s, highlighting the Pol δ - Pol ε handoff during early leading-strand synthesis. Furthermore, the pattern of rNMP incorporation is markedly distinct between the leading the lagging strand. Overall, our results show the different counts and patterns of rNMP incorporation during DNA replication from ARS, which reflects the different labor of division and rNMP incorporation pattern of Pol δ and Pol ε.

scholarly journals Cell cycle localization dynamics of mitochondrial DNA polymerase IC in African trypanosomes

2018 ◽  
Vol 29 (21) ◽  
pp. 2540-2552 ◽  
Author(s):  
Jeniffer Concepción-Acevedo ◽  
Jonathan C. Miller ◽  
Michael J. Boucher ◽  
Michele M. Klingbeil
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Dna Polymerase ◽  
Dna Polymerases ◽  
Dynamic Environment ◽  
African Trypanosomes ◽  
Protein Levels ◽  
Replication Sites ◽  
Cycle Dependent ◽  
Mitochondrial Dna Polymerase

Trypanosoma brucei has a unique catenated mitochondrial DNA (mtDNA) network called kinetoplast DNA (kDNA). Replication of kDNA occurs once per cell cycle in near synchrony with nuclear S phase and requires the coordination of many proteins. Among these are three essential DNA polymerases (TbPOLIB, IC, and ID). Localization dynamics of these proteins with respect to kDNA replication stages and how they coordinate their functions during replication are not well understood. We previously demonstrated that TbPOLID undergoes dynamic localization changes that are coupled to kDNA replication events. Here, we report the localization of TbPOLIC, a second essential DNA polymerase, and demonstrate the accumulation of TbPOLIC foci at active kDNA replication sites (antipodal sites) during stage II of the kDNA duplication cycle. While TbPOLIC was undetectable by immunofluorescence during other cell cycle stages, steady-state protein levels measured by Western blot remained constant. TbPOLIC foci colocalized with the fraction of TbPOLID that localized to the antipodal sites. However, the partial colocalization of the two essential DNA polymerases suggests a highly dynamic environment at the antipodal sites to coordinate the trafficking of replication proteins during kDNA synthesis. These data indicate that cell cycle–dependent localization is a major regulatory mechanism for essential mtDNA polymerases during kDNA replication.

scholarly journals Both DNA Polymerases δ and ε Contact Active and Stalled Replication Forks Differently

2017 ◽  
Vol 37 (21) ◽  
Author(s):  
Chuanhe Yu ◽  
Haiyun Gan ◽  
Zhiguo Zhang
Keyword(s):  
Dna Synthesis ◽  
Dna Polymerase ◽  
Genome Duplication ◽  
Dna Polymerases ◽  
Distinct Pattern ◽  
Replication Forks ◽  
Okazaki Fragments ◽  
Dna Replication Stress ◽  
Leading Strand ◽  
Stalled Replication Forks

ABSTRACT Three DNA polymerases, polymerases α, δ, and ε (Pol α, Pol δ, and Pol ε), are responsible for eukaryotic genome duplication. When DNA replication stress is encountered, DNA synthesis stalls until the stress is ameliorated. However, it is not known whether there is a difference in the association of each polymerase with active and stalled replication forks. Here, we show that each DNA polymerase has a distinct pattern of association with active and stalled replication forks. Pol α is enriched at extending Okazaki fragments of active and stalled forks. In contrast, although Pol δ contacts the nascent lagging strands of active and stalled forks, it binds to only the matured (and not elongating) Okazaki fragments of stalled forks. Pol ε has greater contact with the nascent single-stranded DNA (ssDNA) of the leading strand on active forks than on stalled forks. We propose that the configuration of DNA polymerases at stalled forks facilitates the resumption of DNA synthesis after stress removal.

scholarly journals A polar filter in DNA polymerases prevents ribonucleotide incorporation

2019 ◽  
Vol 47 (20) ◽  
pp. 10693-10705 ◽  
Author(s):  
Mary K Johnson ◽  
Jithesh Kottur ◽  
Deepak T Nair
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Active Site ◽  
Mycobacterium Smegmatis ◽  
Dna Polymerases ◽  
Drastic Reduction ◽  
Equivalent Residue ◽  
Stringent Selection ◽  
Selection For ◽  
Dna Polymerase Iv

Abstract The presence of ribonucleotides in DNA can lead to genomic instability and cellular lethality. To prevent adventitious rNTP incorporation, the majority of the DNA polymerases (dPols) possess a steric filter. The dPol named MsDpo4 (Mycobacterium smegmatis) naturally lacks this steric filter and hence is capable of rNTP addition. The introduction of the steric filter in MsDpo4 did not result in complete abrogation of the ability of this enzyme to incorporate ribonucleotides. In comparison, DNA polymerase IV (PolIV) from Escherichia coli exhibited stringent selection for deoxyribonucleotides. A comparison of MsDpo4 and PolIV led to the discovery of an additional polar filter responsible for sugar selectivity. Thr43 represents the filter in PolIV and this residue forms interactions with the incoming nucleotide to draw it closer to the enzyme surface. As a result, the 2’-OH in rNTPs will clash with the enzyme surface, and therefore ribonucleotides cannot be accommodated in the active site in a conformation compatible with productive catalysis. The substitution of the equivalent residue in MsDpo4–Cys47, with Thr led to a drastic reduction in the ability of the mycobacterial enzyme to incorporate rNTPs. Overall, our studies evince that the polar filter serves to prevent ribonucleotide incorporation by dPols.

scholarly journals DNA polymerases from Chlamydomonas reinhardii. Further characterization, action of inhibitors and associated nuclease activities

1978 ◽  
Vol 171 (1) ◽  
pp. 241-249 ◽  
Author(s):  
C A Ross ◽  
W J Harris
Keyword(s):  
Dna Polymerase ◽  
Dna Polymerases ◽  
Nuclease Activity ◽  
Heat Sensitivity ◽  
Dna Templates ◽  
Chlamydomonas Reinhardii ◽  
Synthetic Dna ◽  
Catalytically Active ◽  
Dna Primers ◽  
Deoxyribonuclease Activity

The properties of three DNA polymerase species A, B and C, purified from Chlamydomonas reinhardii were compared. DNA polymerases A and B have Km values with respect to deoxyribonucleoside triphosphates of 19 micron and 3 micron respectively. DNA polymerase A is most active with activated DNA, but will also use native DNA and synthetic RNA and DNA templates with DNA primers. DNA polymerase B is also most active with activated DNA, but will use denatured DNA and synthetic DNA templates. It is inactive with RNA templates. DNA polymerase B is completely inactive in the presence of 100 micron-heparin, which has no effect on DNA polymerase A activity. Heparin dissociates DNA polymerase B into subunits that are still catalytically active, but which heparin inhibited. DNA polymerase B possesses deoxyribonuclease activity that is inhibited by 5 micron-heparin, suggesting that the deoxyribonuclease is an integral part of the DNA polymerase moiety. DNA polymerase A is devoid of nuclease activity. DNA polymerase C is similar to DNA polymerase B in all these properties, though it is more active with RNA primers and has greater heat-sensitivity.

scholarly journals A Mutation in DNA Polymerase α Rescues WEE1KO Sensitivity to HU

2021 ◽  
Vol 22 (17) ◽  
pp. 9409
Author(s):  
Thomas Eekhout ◽  
José Antonio Pedroza-Garcia ◽  
Pooneh Kalhorzadeh ◽  
Geert De Jaeger ◽  
Lieven De Veylder
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Polymerase ◽  
Driving Force ◽  
S Phase ◽  
Catalytic Subunit ◽  
Genomic Integrity ◽  
Cyclin Dependent Kinases ◽  
Dna Polymerase Α ◽  
Wee1 Kinase

During DNA replication, the WEE1 kinase is responsible for safeguarding genomic integrity by phosphorylating and thus inhibiting cyclin-dependent kinases (CDKs), which are the driving force of the cell cycle. Consequentially, wee1 mutant plants fail to respond properly to problems arising during DNA replication and are hypersensitive to replication stress. Here, we report the identification of the polα-2 mutant, mutated in the catalytic subunit of DNA polymerase α, as a suppressor mutant of wee1. The mutated protein appears to be less stable, causing a loss of interaction with its subunits and resulting in a prolonged S-phase.

scholarly journals Both DNA Polymerases δ and ε Contact Active and Stalled Replication Forks differently

2017 ◽  
Author(s):  
Chuanhe Yu ◽  
Haiyun Gan ◽  
Zhiguo Zhang
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Genome Duplication ◽  
Dna Polymerases ◽  
Replication Forks ◽  
Okazaki Fragments ◽  
Dna Replication Stress ◽  
Leading Strand ◽  
Stalled Replication Forks

AbstractThree DNA polymerases (Pol α, Pol δ, and Pol ε) are responsible for eukaryotic genome duplication. When DNA replication stress is encountered, DNA synthesis stalls until the stress is ameliorated. However, it is not known whether there is a difference in the association of each polymerase with active and stalled replication forks. Here, we show that each DNA polymerase has distinct patterns of association with active and stalled replication forks. Pol α is enriched at extending Okazaki fragments of active and stalled forks. In contrast, although Pol δ contacts the nascent lagging strands of active and stalled forks, it binds to only the matured (and not elongating) Okazaki fragments of stalled forks. Pol ε has a greater contact with the nascent ssDNA of leading strand on active forks compared with stalled forks. We propose that the configuration of DNA polymerases at stalled forks facilitate resumption of DNA synthesis after stress removal.

PrimPol (Primase/Polymerase), replicating enzyme – A mini review

2020 ◽  
Vol 2 (4) ◽  
pp. 89-92
Author(s):  
Muhammad Amir ◽  
Sabeera Afzal ◽  
Alia Ishaq
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Genetic Information ◽  
Nuclear Dna ◽  
De Novo ◽  
Dna Polymerases ◽  
Test Site ◽  
Mitochondrial Dna Replication ◽  
Dna Template ◽  
Preliminary Phase

Polymerases were revealed first in 1970s. Most important to the modest perception the enzyme responsible for nuclear DNA replication that was pol , for DNA repair pol and for mitochondrial DNA replication pol  DNA construction and renovation done by DNA polymerases, so directing both the constancy and discrepancy of genetic information. Replication of genome initiate with DNA template-dependent fusion of small primers of RNA. This preliminary phase in replication of DNA demarcated as de novo primer synthesis which is catalyzed by specified polymerases known as primases. Sixteen diverse DNA-synthesizing enzymes about human perspective are devoted to replication, reparation, mutilation lenience, and inconsistency of nuclear DNA. But in dissimilarity, merely one DNA polymerase has been called in mitochondria. It has been suggest that PrimPol is extremely acting the roles by re-priming DNA replication in mitochondria to permit an effective and appropriate way replication to be accomplished. Investigations from a numeral of test site have significantly amplified our appreciative of the role, recruitment and regulation of the enzyme during DNA replication. Though, we are simply just start to increase in value the versatile roles that play PrimPol in eukaryote.

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