scholarly journals Role of the Schizosaccharomyces pombe F-Box DNA Helicase in Processing Recombination Intermediates

2005 ◽  
Vol 25 (18) ◽  
pp. 8074-8083 ◽  
Author(s):  
Takashi Morishita ◽  
Fumiko Furukawa ◽  
Chikako Sakaguchi ◽  
Takashi Toda ◽  
Antony M. Carr ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Schizosaccharomyces Pombe ◽  
Genomic Library ◽  
Dna Helicase ◽  
Gene Encoding ◽  
Focus Formation ◽  
Synthetic Lethal ◽  
Recombination Repair ◽  
Γ Rays

ABSTRACT In an effort to identify novel genes involved in recombination repair, we isolated fission yeast Schizosaccharomyces pombe mutants sensitive to methyl methanesulfonate (MMS) and a synthetic lethal with rad2. A gene that complements such mutations was isolated from the S. pombe genomic library, and subsequent analysis identified it as the fbh1 gene encoding the F-box DNA helicase, which is conserved in mammals but not conserved in Saccharomyces cerevisiae. An fbh1 deletion mutant is moderately sensitive to UV, MMS, and γ rays. The rhp51 (RAD51 ortholog) mutation is epistatic to fbh1. fbh1 is essential for viability in stationary-phase cells and in the absence of either Srs2 or Rqh1 DNA helicase. In each case, lethality is suppressed by deletion of the recombination gene rhp57. These results suggested that fbh1 acts downstream of rhp51 and rhp57. Following UV irradiation or entry into the stationary phase, nuclear chromosomal domains of the fbh1Δ mutant shrank, and accumulation of some recombination intermediates was suggested by pulsed-field gel electrophoresis. Focus formation of Fbh1 protein was induced by treatment that damages DNA. Thus, the F-box DNA helicase appears to process toxic recombination intermediates, the formation of which is dependent on the function of Rhp51.

scholarly journals A Recombination Repair Gene of Schizosaccharomyces pombe, rhp57, Is a Functional Homolog of the Saccharomyces cerevisiae RAD57 Gene and Is Phylogenetically Related to the Human XRCC3 Gene

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1451-1461 ◽  
Author(s):  
Yasuhiro Tsutsui ◽  
Takashi Morishita ◽  
Hiroshi Iwasaki ◽  
Hiroyuki Toh ◽  
Hideo Shinagawa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Schizosaccharomyces Pombe ◽  
Genomic Library ◽  
Synthetic Lethality ◽  
Multicopy Plasmid ◽  
Repair Gene ◽  
Recombination Repair ◽  
Xrcc3 Gene ◽  
Γ Rays ◽  
Lower Temperature

Abstract To identify Schizosaccharomyces pombe genes involved in recombination repair, we identified seven mutants that were hypersensitive to both methyl methanesulfonate (MMS) and γ-rays and that contained mutations that caused synthetic lethality when combined with a rad2 mutation. One of the mutants was used to clone the corresponding gene from a genomic library by complementation of the MMS-sensitive phenotype. The gene obtained encodes a protein of 354 amino acids whose sequence is 32% identical to that of the Rad57 protein of Saccharomyces cerevisiae. An rhp57 (RAD57 homolog of S. pombe) deletion strain was more sensitive to MMS, UV, and γ-rays than the wild-type strain and showed a reduction in the frequency of mitotic homologous recombination. The MMS sensitivity was more severe at lower temperature and was suppressed by the presence of a multicopy plasmid bearing the rhp51 gene. An rhp51 rhp57 double mutant was as sensitive to UV and γ-rays as an rhp51 single mutant, indicating that rhp51 function is epistatic to that of rhp57. These characteristics of the rhp57 mutants are very similar to those of S. cerevisiae rad57 mutants. Phylogenetic analysis suggests that Rhp57 and Rad57 are evolutionarily closest to human Xrcc3 of the RecA/Rad51 family of proteins.

scholarly journals Rhp51-Dependent Recombination Intermediates That Do Not Generate Checkpoint Signal Are Accumulated in Schizosaccharomyces pombe rad60 and smc5/6 Mutants after Release from Replication Arrest

2006 ◽  
Vol 26 (1) ◽  
pp. 343-353 ◽  
Author(s):  
Izumi Miyabe ◽  
Takashi Morishita ◽  
Takashi Hishida ◽  
Shuji Yonei ◽  
Hideo Shinagawa
Keyword(s):  
Dna Replication ◽  
Schizosaccharomyces Pombe ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Strand Breaks ◽  
Replication Arrest ◽  
Recombination Repair ◽  
Structural Maintenance Of Chromosomes ◽  
Mutant Cells

ABSTRACT The Schizosaccharomyces pombe rad60 gene is essential for cell growth and is involved in repairing DNA double-strand breaks. Rad60 physically interacts with and is functionally related to the structural maintenance of chromosomes 5 and 6 (SMC5/6) protein complex. In this study, we investigated the role of Rad60 in the recovery from the arrest of DNA replication induced by hydroxyurea (HU). rad60-1 mutant cells arrested mitosis normally when treated with HU. Significantly, Rad60 function is not required during HU arrest but is required on release. However, the mutant cells underwent aberrant mitosis accompanied by irregular segregation of chromosomes, and DNA replication was not completed, as revealed by pulsed-field gel electrophoresis. The deletion of rhp51 suppressed the aberrant mitosis of rad60-1 cells and caused mitotic arrest. These results suggest that Rhp51 and Rad60 are required for the restoration of a stalled or collapsed replication fork after release from the arrest of DNA replication by HU. The rad60-1 mutant was proficient in Rhp51 focus formation after release from the HU-induced arrest of DNA replication or DNA-damaging treatment. Furthermore, the lethality of a rad60-1 rqh1Δ double mutant was suppressed by the deletion of rhp51 or rhp57. These results suggest that Rad60 is required for recombination repair at a step downstream of Rhp51. We propose that Rhp51-dependent DNA structures that cannot activate the mitotic checkpoints accumulate in rad60-1 cells.

scholarly journals The Schizosaccharomyces pombe dim1+ Gene Interacts with the Anaphase-Promoting Complex or Cyclosome (APC/C) Component lid1+ and Is Required for APC/C Function

1999 ◽  
Vol 19 (4) ◽  
pp. 2535-2546 ◽  
Author(s):  
Lynne D. Berry ◽  
Anna Feoktistova ◽  
Melanie D. Wright ◽  
Kathleen L. Gould
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Chromosome Segregation ◽  
State Level ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Anaphase Promoting Complex ◽  
Synthetic Lethal ◽  
C Complex ◽  
Mutant Cells

ABSTRACT The Schizosaccharomyces pombe dim1 + gene is required for entry into mitosis and for chromosome segregation during mitosis. To further understand dim1p function, we undertook a synthetic lethal screen with the temperature-sensitive dim1-35 mutant and isolated lid (for lethal in dim1-35) mutants. Here, we describe the temperature-sensitive lid1-6mutant. At the restrictive temperature of 36°C, lid1-6mutant cells arrest with a “cut” phenotype similar to that ofcut4 and cut9 mutants. An epitope-tagged version of lid1p is a component of a multiprotein ∼20S complex; the presence of lid1p in this complex depends upon functionalcut9 +. lid1p-myc coimmunoprecipitates with several other proteins, including cut9p and nuc2p, and the presence of cut9p in a 20S complex depends upon the activity oflid1 +. Further, lid1 +function is required for the multiubiquitination of cut2p, an anaphase-promoting complex or cyclosome (APC/C) target. Thus, lid1p is a component of the S. pombe APC/C. In dim1mutants, the abundances of lid1p and the APC/C complex decline significantly, and the ubiquitination of an APC/C target is abolished. These data suggest that at least one role of dim1p is to maintain or establish the steady-state level of the APC/C.

scholarly journals Isolation from Ochrobactrum anthropi of a Novel Class II 5-Enopyruvylshikimate-3-Phosphate Synthase with High Tolerance to Glyphosate

2010 ◽  
Vol 76 (17) ◽  
pp. 6001-6005 ◽  
Author(s):  
Yong-Sheng Tian ◽  
Ai-Sheng Xiong ◽  
Jing Xu ◽  
Wei Zhao ◽  
Feng Gao ◽  
...  
Keyword(s):  
Genomic Library ◽  
Site Directed Mutagenesis ◽  
Single Amino Acid ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Construction Process ◽  
Ochrobactrum Anthropi ◽  
Gene Encoding ◽  
Phosphate Synthase

ABSTRACT Applying the genomic library construction process and colony screening, a novel aro A gene encoding 5-enopyruvylshikimate-3-phosphate synthase from Ochrobactrum anthropi was identified, cloned, and overexpressed, and the enzyme was purified to homogeneity. Furthermore, site-directed mutagenesis was employed to assess the role of single amino acid residues in glyphosate resistance.

scholarly journals Participation of the HIM1 gene of yeast Saccharomyces cerevisiae in the error-free branch of post-replicative repair and role Polη in him1-dependent mutagenesis

2020 ◽  
Author(s):  
E. A. Alekseeva ◽  
T. A. Evstyukhina ◽  
V. T. Peshekhonov ◽  
V. G. Korolev
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Damage Tolerance ◽  
Dna Damage Tolerance ◽  
Uv Mutagenesis ◽  
Gene Encoding ◽  
Yeast Saccharomyces Cerevisiae ◽  
Recombination Repair ◽  
Repair Pathways

Abstract In eukaryotes, DNA damage tolerance (DDT) is determined by two repair pathways, homologous repair recombination (HRR) and a pathway controlled by the RAD6-epistatic group of genes. Monoubiquitylation of PCNA mediates an error-prone pathway, whereas polyubiquitylation stimulates an error-free pathway. The error-free pathway involves components of recombination repair; however, the factors that act in this pathway remain largely unknown. Here, we report that the HIM1 gene participates in error-free DDT. Notably, inactivation RAD30 gene encoding Polη completely suppresses him1-dependent UV mutagenesis. Furthermore, data obtained show a significant role of Polη in him1-dependent mutagenesis, especially at non-bipyrimidine sites (NBP sites). We demonstrate that him1 mutation significantly reduces the efficiency of the induction expression of RNR genes after UV irradiation. Besides, this paper presents evidence that significant increase in the dNTP levels suppress him1-dependent mutagenesis. Our findings show that Polη responsible for him1-dependent mutagenesis.

scholarly journals Phage Shock Protein PspA of Escherichia coli Relieves Saturation of Protein Export via the Tat Pathway

2004 ◽  
Vol 186 (2) ◽  
pp. 366-373 ◽  
Author(s):  
Matthew P. DeLisa ◽  
Philip Lee ◽  
Tracy Palmer ◽  
George Georgiou
Keyword(s):  
Genomic Library ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Protein A ◽  
Homologous Proteins ◽  
Gene Encoding ◽  
Protein Precursor ◽  
Twin Arginine Translocation ◽  
Tat Pathway

ABSTRACT Overexpression of either heterologous or homologous proteins that are routed to the periplasm via the twin-arginine translocation (Tat) pathway results in a block of export and concomitant accumulation of the respective protein precursor in the cytoplasm. Screening of a plasmid-encoded genomic library for mutants that confer enhanced export of a TorA signal sequence (ssTorA)-GFP-SsrA fusion protein, and thus result in higher cell fluorescence, yielded the pspA gene encoding phage shock protein A. Coexpression of pspA relieved the secretion block observed with ssTorA-GFP-SsrA or upon overexpression of the native Tat proteins SufI and CueO. A similar effect was observed with the Synechocystis sp. strain PCC6803 PspA homologue, VIPP1, indicating that the role of PspA in Tat export may be phylogenetically conserved. Mutations in Tat components that completely abolish export result in a marked induction of PspA protein synthesis, consistent with its proposed role in enhancing protein translocation via Tat.

scholarly journals Transcriptional Organization and In Vivo Role of theEscherichia coli rsd Gene, Encoding the Regulator of RNA Polymerase Sigma D

1999 ◽  
Vol 181 (12) ◽  
pp. 3768-3776 ◽  
Author(s):  
Miki Jishage ◽  
Akira Ishihama
Keyword(s):  
Rna Polymerase ◽  
Stationary Phase ◽  
Null Mutant ◽  
Gene Encoding ◽  
Transcription In Vitro ◽  
Extension Analysis ◽  
Insight Into

ABSTRACT The regulator of sigma D (Rsd) was identified as an RNA polymerase ς70-associated protein in stationary-phaseEscherichia coli with the inhibitory activity of ς70-dependent transcription in vitro (M. Jishage and A. Ishihama, Proc. Natl. Acad. Sci. USA 95:4953–4958, 1998). Primer extension analysis of rsd mRNA indicated the presence of two promoters, ςS-dependent P1 and ς70-dependent P2 with the gearbox sequence. To get insight into the in vivo role of Rsd, the expression of a reporter gene fused to either the ς70- or ςS-dependent promoter was analyzed in the absence of Rsd or the presence of overexpressed Rsd. In the rsd null mutant, the ς70- and ςS-dependent gene expression was increased or decreased, respectively. On the other hand, the ς70- or ςS-dependent transcription was reduced or enhanced, respectively, after overexpression of Rsd. The repression of the ςS-dependent transcription in the rsd mutant is overcome by increased production of the ςS subunit. Together these observations support the prediction that Rsd is involved in replacement of the RNA polymerase ς subunit from ς70 to ςS during the transition from exponential growth to the stationary phase.

scholarly journals CztR, a LysR-Type Transcriptional Regulator Involved in Zinc Homeostasis and Oxidative Stress Defense in Caulobacter crescentus

2010 ◽  
Vol 192 (20) ◽  
pp. 5480-5488 ◽  
Author(s):  
Vânia S. Braz ◽  
José F. da Silva Neto ◽  
Valéria C. S. Italiani ◽  
Marilis V. Marques
Keyword(s):  
Stationary Phase ◽  
Mutant Strain ◽  
Caulobacter Crescentus ◽  
Transcriptional Start Site ◽  
Hypothetical Protein ◽  
Zinc Homeostasis ◽  
Gene Encoding ◽  
Transmembrane Segments ◽  
Zinc Depletion

ABSTRACT Caulobacter crescentus is a free-living alphaproteobacterium that has 11 predicted LysR-type transcriptional regulators (LTTRs). Previously, a C. crescentus mutant strain with a mini-Tn5lacZ transposon inserted into a gene encoding an LTTR was isolated; this mutant was sensitive to cadmium. In this work, a mutant strain with a deletion was obtained, and the role of this LTTR (called CztR here) was evaluated. The transcriptional start site of this gene was determined by primer extension analysis, and its promoter was cloned in front of a lacZ reporter gene. β-Galactosidase activity assays, performed with the wild-type and mutant strains, indicated that this gene is 2-fold induced when cells enter stationary phase and that it is negatively autoregulated. Moreover, this regulator is essential for the expression of the divergent cztA gene at stationary phase, in minimal medium, and in response to zinc depletion. This gene encodes a hypothetical protein containing 10 predicted transmembrane segments, and its expression pattern suggests that it encodes a putative zinc transporter. The cztR strain was also shown to be sensitive to superoxide (generated by paraquat) and to hydrogen peroxide but not to tert-butyl hydroperoxide. The expression of katG and ahpC, but not that of the superoxide dismutase genes, was increased in the cztR mutant. A model is proposed to explain how CztR binding to the divergent regulatory regions could activate cztA expression and repress its own transcription.

scholarly journals Isolation and Characterization of rpoS from a Pathogenic Bacterium, Vibrio vulnificus: Role of σS in Survival of Exponential-Phase Cells under Oxidative Stress

2004 ◽  
Vol 186 (11) ◽  
pp. 3304-3312 ◽  
Author(s):  
Kyung-Je Park ◽  
Min-Jin Kang ◽  
Songhee H. Kim ◽  
Hyun-Jung Lee ◽  
Jae-Kyu Lim ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stationary Phase ◽  
Vibrio Vulnificus ◽  
Stationary Phases ◽  
Exponential Phase ◽  
Knockout Mutant ◽  
Gene Encoding ◽  
Isolation And Characterization ◽  
Multiple Copies

ABSTRACT A gene homologous to rpoS was cloned from a fatal human pathogen, Vibrio vulnificus. The functional role of rpoS in V. vulnificus was accessed by using an rpoS knockout mutant strain. This mutant was impaired in terms of the ability to survive under oxidative stress, nutrient starvation, UV irradiation, or acidic conditions. The increased susceptibility of the V. vulnificus mutant in the exponential phase to H2O2 was attributed to the reduced activity of hydroperoxidase I (HPI). Although σS synthesis was induced and HPI activity reached the maximal level in the stationary phase, the mutant in the stationary phase showed the same susceptibility to H2O2 as the wild-type strain in the stationary phase. In addition, HPII activity, which is known to be controlled by σS in Escherichia coli, was not detectable in V. vulnificus strains under the conditions tested. The mutant in the exponential phase complemented with multiple copies of either the rpoS or katG gene of V. vulnificus recovered both resistance to H2O2 and HPI activity compared with the control strain. Expression of the katG gene encoding HPI in V. vulnificus was monitored by using a katG::luxAB transcriptional fusion. The expression of this gene was significantly reduced by deletion of σS in both the early exponential and late stationary phases. Thus, σS is necessary for increased synthesis and activity of HPI, and σS is required for exponentially growing V. vulnificus to develop the ability to survive in the presence of H2O2.

scholarly journals Effects of A6E Mutation on Protein Expression and Supramolecular Assembly of Yeast Asparagine Synthetase

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 294
Author(s):  
Thunyarat Surasiang ◽  
Chalongrat Noree
Keyword(s):  
Protein Expression ◽  
Stationary Phase ◽  
Lymphoblastic Leukemia ◽  
Energy Levels ◽  
Supramolecular Assembly ◽  
Asparagine Synthetase ◽  
Gene Encoding ◽  
Synthetase Deficiency ◽  
Asparagine Synthetase Deficiency ◽  
Intracellular Energy

Asparagine synthetase deficiency (ASD) has been found to be caused by certain mutations in the gene encoding human asparagine synthetase (ASNS). Among reported mutations, A6E mutation showed the greatest reduction in ASNS abundance. However, the effect of A6E mutation has not yet been tested with yeast asparagine synthetase (Asn1/2p). Here, we constructed a yeast strain by deleting ASN2 from its genome, introducing the A6E mutation codon to ASN1, along with GFP downstream of ASN1. Our mutant yeast construct showed a noticeable decrease of Asn1p(A6E)-GFP levels as compared to the control yeast expressing Asn1p(WT)-GFP. At the stationary phase, the A6E mutation also markedly lowered the assembly frequency of the enzyme. In contrast to Asn1p(WT)-GFP, Asn1p(A6E)-GFP was insensitive to changes in the intracellular energy levels upon treatment with sodium azide during the log phase or fresh glucose at the stationary phase. Our study has confirmed that the effect of A6E mutation on protein expression levels of asparagine synthetase is common in both unicellular and multicellular eukaryotes, suggesting that yeast could be a model of ASD. Furthermore, A6E mutation could be introduced to the ASNS gene of acute lymphoblastic leukemia patients to inhibit the upregulation of ASNS by cancer cells, reducing the risk of developing resistance to the asparaginase treatment.

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