scholarly journals Cdc23/Mcm10 Primase Generates the Lagging Strand-Specific Ribonucleotide Imprint in Fission Yeast

2018 ◽  
Author(s):  
Balveer Singh ◽  
Kamlesh K Bisht ◽  
Udita Upadhyay ◽  
Avinash Chandra Kushwaha ◽  
Jagpreet Singh Nanda ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Dna Polymerase ◽  
Parental Cell ◽  
Cell Type ◽  
Direct Role ◽  
Type Locus ◽  
Daughter Cells ◽  
Dna Strand ◽  
Lagging Strand

AbstractThe developmental asymmetry of fission yeast daughter cells derives from inheriting “older Watson” versus “older Crick” DNA strand from the parental cell, strands that are complementary but not identical with each other. A novel DNA strand-specific “imprint”, installed during DNA replication at the mating-type locus (mat1), imparts competence for cell type inter-conversion to one of the two chromosome replicas. The biochemical nature of the imprint and the mechanism of its installation are still not understood. The catalytic subunit of DNA Polymerase α (Polα) has been implicated in the imprinting process. Based on its known biochemical function, Polα might install the mat1 imprint during lagging strand synthesis. The nature of the imprint is not clear: it is either a nick or a ribonucleotide insertion. Our investigations do not support a role of Polα in nicking through putative endonuclease domains but confirm its role in installing an alkali-labile moiety as the imprint. A detailed genetic and molecular analysis reveals a direct role of the Cdc23/Mcm10 primase activity in installing the imprint in cooperation with Polα and Swi1.

Role of Extracellular Adenosine Triphosphate in Human Skin

2004 ◽  
Vol 8 (2) ◽  
pp. 90-96 ◽  
Author(s):  
Aton M. Holzer ◽  
Richard D. Granstein
Keyword(s):  
Human Skin ◽  
Adenosine Triphosphate ◽  
Current Knowledge ◽  
Extracellular Atp ◽  
Cell Type ◽  
Skin Injury ◽  
Direct Role ◽  
Extracellular Adenosine ◽  
Proliferation And Apoptosis

Background: The nucleotide adenosine triphosphate (ATP) has long been known to drive and participate in countless intracellular processes. Extracellular ATP and its metabolite adenosine have also been shown to exert a variety of effects on nearly every cell type in human skin. Knowledge of the sources and effects of extracellular ATP in human skin may help shape new therapies for skin injury, inflammation, and numerous other cutaneous disorders. Objective: The objective of this review is to introduce the reader to current knowledge regarding the sources and effects of extracellular ATP in human skin and to outline areas in which further research is necessary to clarify the nature and mechanism of these effects. Conclusion: Extracellular ATP seems to play a direct role in triggering skin inflammatory, regenerative, and fibrotic responses to mechanical injury, an indirect role in melanocyte proliferation and apoptosis, and a complex role in Langerhans cell-directed adaptive immunity.

scholarly journals The Werner Syndrome Helicase Coordinates Sequential Strand Displacement and FEN1-Mediated Flap Cleavage during Polymerase δ Elongation

2016 ◽  
Vol 37 (3) ◽  
Author(s):  
Baomin Li ◽  
Sita Reddy ◽  
Lucio Comai
Keyword(s):  
Dna Polymerase ◽  
Werner Syndrome ◽  
Physiological Role ◽  
Cooperative Interaction ◽  
Strand Displacement ◽  
Winged Helix ◽  
Werner Syndrome Protein ◽  
Syndrome Protein ◽  
Lagging Strand

ABSTRACT The Werner syndrome protein (WRN) suppresses the loss of telomeres replicated by lagging-strand synthesis by a yet to be defined mechanism. Here, we show that whereas either WRN or the Bloom syndrome helicase (BLM) stimulates DNA polymerase δ progression across telomeric G-rich repeats, only WRN promotes sequential strand displacement synthesis and FEN1 cleavage, a critical step in Okazaki fragment maturation, at these sequences. Helicase activity, as well as the conserved winged-helix (WH) motif and the helicase and RNase D C-terminal (HRDC) domain play important but distinct roles in this process. Remarkably, WRN also influences the formation of FEN1 cleavage products during strand displacement on a nontelomeric substrate, suggesting that WRN recruitment and cooperative interaction with FEN1 during lagging-strand synthesis may serve to regulate sequential strand displacement and flap cleavage at other genomic sites. These findings define a biochemical context for the physiological role of WRN in maintaining genetic stability.

scholarly journals Essential Role of Sna41/Cdc45 in Loading of DNA Polymerase α onto Minichromosome Maintenance Proteins in Fission Yeast

2001 ◽  
Vol 276 (28) ◽  
pp. 26189-26196 ◽  
Author(s):  
Masashi Uchiyama ◽  
Dominic Griffiths ◽  
Ken-ichi Arai ◽  
Hisao Masai
Keyword(s):  
Fission Yeast ◽  
Dna Polymerase ◽  
Essential Role ◽  
Minichromosome Maintenance ◽  
Dna Polymerase Α

scholarly journals A Recombinationally Repressed Region Between mat2 and mat3 Loci Shares Homology to Centromeric Repeats and Regulates Directionality of Mating-Type Switching in Fission Yeast

Genetics ◽  
1997 ◽  
Vol 146 (4) ◽  
pp. 1221-1238 ◽  
Author(s):  
Shiv I S Grewal ◽  
Amar J S Klar
Keyword(s):  
Fission Yeast ◽  
Mating Type ◽  
Sequencing Analysis ◽  
Cell Type ◽  
Cloning And Sequencing ◽  
Type Region ◽  
Repeat Sequences ◽  
Mating Type Switching ◽  
Cell Type Specific

Cells of the fission yeast Schizosaccharomyces pombe switch mating type by replacing genetic information at the transcriptionally active mat1 locus with sequences copied from one of two closely linked silent loci, mat2-P or mat3-M. By a process referred to as directionality of switching, cells predominantly switch to the opposite mat1 allele; the mat1-P allele preferentially recombines with mat3, while mat1-M selects the mat2. In contrast to efficient recombination at mat1, recombination within the adjoining mat2-mat3 interval is undetectable. We defined the role of sequences between mat2 and mat3, designated the K-region, in directionality as well as recombinational suppression. Cloning and sequencing analysis revealed that a part of the K-region is homologous to repeat sequences present at centromeres, which also display transcriptional and recombinational suppression. Replacement of 7.5 kb of the K-region with the ura4  + gene affected directionality in a variegated manner. Analysis of the swi6-mod locus, which was previously shown to affect directionality, in KΔ::ura4  + strains suggested the existence of at least two overlapping directionality mechanisms. Our work furthers the model that directionality is regulated by cell-type-specific organization of the heterochromatin-like structure in the mating-type region and provides evidence that the K-region contributes to silencing of the mat2-mat3 interval.

scholarly journals Role of Tropomyosin in Formin-mediated Contractile Ring Assembly in Fission Yeast

2009 ◽  
Vol 20 (8) ◽  
pp. 2160-2173 ◽  
Author(s):  
Colleen T. Skau ◽  
Erin M. Neidt ◽  
David R. Kovar
Keyword(s):  
Fission Yeast ◽  
Actin Filament ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Actin Assembly ◽  
Animal Cells ◽  
Contractile Ring ◽  
Direct Role ◽  
Ring Assembly

Like animal cells, fission yeast divides by assembling actin filaments into a contractile ring. In addition to formin Cdc12p and profilin, the single tropomyosin isoform SpTm is required for contractile ring assembly. Cdc12p nucleates actin filaments and remains processively associated with the elongating barbed end while driving the addition of profilin-actin. SpTm is thought to stabilize mature filaments, but it is not known how SpTm localizes to the contractile ring and whether SpTm plays a direct role in Cdc12p-mediated actin polymerization. Using “bulk” and single actin filament assays, we discovered that Cdc12p can recruit SpTm to actin filaments and that SpTm has diverse effects on Cdc12p-mediated actin assembly. On its own, SpTm inhibits actin filament elongation and depolymerization. However, Cdc12p completely overcomes the combined inhibition of actin nucleation and barbed end elongation by profilin and SpTm. Furthermore, SpTm increases the length of Cdc12p-nucleated actin filaments by enhancing the elongation rate twofold and by allowing them to anneal end to end. In contrast, SpTm ultimately turns off Cdc12p-mediated elongation by “trapping” Cdc12p within annealed filaments or by dissociating Cdc12p from the barbed end. Therefore, SpTm makes multiple contributions to contractile ring assembly during and after actin polymerization.

scholarly journals Deletions in plasmid pBR322: replication slippage involving leading and lagging strands.

Genetics ◽  
1991 ◽  
Vol 127 (4) ◽  
pp. 649-655
Author(s):  
K Weston-Hafer ◽  
D E Berg
Keyword(s):  
Replication Origin ◽  
Direct Repeat ◽  
Insertion Mutant ◽  
Plasmid Pbr322 ◽  
Prior Work ◽  
Direct Repeats ◽  
Replication Slippage ◽  
Dna Strand ◽  
Lagging Strand

Abstract We test here whether a class of deletions likely to result from errors during DNA replication arise preferentially during synthesis of either the leading or the lagging DNA strand. Deletions were obtained by reversion of particular insertion mutant alleles of the pBR322 amp gene. The alleles contain insertions of palindromic DNAs bracketed by 9-bp direct repeats of amp sequence; in addition, bp 2 to 5 in one arm of the palindrome form a direct repeat with 4 bp of adjoining amp sequence. Prior work had shown that reversion to Ampr results from deletions with endpoints in the 8- or 4-bp repeat, and that the 4-bp repeats are used preferentially because one of them is in the palindrome. To test the role of leading and lagging strand synthesis in deletion formation, we reversed the direction of replication of the amp gene by inverting the pBR322 replication origin, and also constructed new mutant alleles with a 4-bp repeat starting counterclockwise rather than clockwise of the insertion. In both cases the 4-bp repeats were used preferentially as deletion endpoints. A model is presented in which deletions arise during elongation of the strand that copies the palindrome before the adjoining 4-bp repeat, and in which preferential use of the 4-bp repeats independent of the overall direction of replication implies that deletions arise during syntheses of both leading and lagging strands.

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 Condensin controls cellular RNA levels through the accurate segregation of chromosomes instead of directly regulating transcription

2018 ◽  
Author(s):  
Clémence Hocquet ◽  
Xavier Robellet ◽  
Laurent Modolo ◽  
Xi-Ming Sun ◽  
Claire Burny ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chromosome Instability ◽  
Yeast Cells ◽  
Compelling Evidence ◽  
Direct Role ◽  
Daughter Cells ◽  
Transcription Process ◽  
Rna Exosome ◽  
Segregation Of Chromosomes

AbstractCondensins are genome organisers that shape chromosomes and promote their accurate transmission. Several studies have also implicated condensins in gene expression, although the mechanisms have remained enigmatic. Here, we report on the role of condensin in gene expression in fission and budding yeasts. In contrast to previous studies, we provide compelling evidence that condensin plays no direct role in the maintenance of the transcriptome, neither during interphase nor during mitosis. We further show that the changes in gene expression in post-mitotic fission yeast cells that result from condensin inactivation are largely a consequence of chromosome missegregation during anaphase, which notably depletes the RNA-exosome from daughter cells. Crucially, preventing karyotype abnormalities in daughter cells restores a normal transcriptome despite condensin inactivation. Thus, chromosome instability, rather than a direct role of condensin in the transcription process, changes gene expression. This knowledge challenges the concept of gene regulation by canonical condensin complexes.

Sign in / Sign up

Export Citation Format

Share Document