scholarly journals Mutations in Homologous Recombination Genes Rescue top3 Slow Growth in Saccharomyces cerevisiae

Genetics ◽  
2002 ◽  
Vol 162 (2) ◽  
pp. 647-662 ◽  
Author(s):  
Erika Shor ◽  
Serge Gangloff ◽  
Marisa Wagner ◽  
Justin Weinstein ◽  
Gavrielle Price ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Type Strain ◽  
Wild Type Strain ◽  
Slow Growth ◽  
Recq Helicase ◽  
Wild Type ◽  
Growth Defects ◽  
Topoisomerase Iii ◽  
Hyper Sensitivity ◽  
Instability Phenotype

Abstract In budding yeast, loss of topoisomerase III, encoded by the TOP3 gene, leads to a genomic instability phenotype that includes slow growth, hyper-sensitivity to genotoxic agents, mitotic hyper-recombination, increased chromosome missegregation, and meiotic failure. Slow growth and other defects of top3 mutants are suppressed by mutation of SGS1, which encodes the only RecQ helicase in S. cerevisiae. sgs1 is epistatic to top3, suggesting that the two proteins act in the same pathway. To identify other factors that function in the Sgs1-Top3 pathway, we undertook a genetic screen for non-sgs1 suppressors of top3 defects. We found that slow growth and DNA damage sensitivity of top3 mutants are suppressed by mutations in RAD51, RAD54, RAD55, and RAD57. In contrast, top3 mutants show extreme synergistic growth defects with mutations in RAD50, MRE11, XRS2, RDH54, and RAD1. We also analyzed recombination at the SUP4-o region, showing that in a rad51, rad54, rad55, or rad57 background top3Δ does not increase recombination to the same degree as in a wild-type strain. These results suggest that the presence of the Rad51 homologous recombination complex in a top3 background facilitates creation of detrimental intermediates by Sgs1. We present a model wherein Rad51 helps recruit Sgs1-Top3 to sites of replicative damage.

Recombination and ligation of transfected DNA in CHO mutant EM9, which has high levels of sister chromatid exchange

1987 ◽  
Vol 7 (5) ◽  
pp. 2007-2011
Author(s):  
C A Hoy ◽  
J C Fuscoe ◽  
L H Thompson
Keyword(s):  
Homologous Recombination ◽  
Sister Chromatid ◽  
Sister Chromatid Exchange ◽  
Type Strain ◽  
Wild Type Strain ◽  
Strand Break ◽  
Wild Type ◽  
Dna Strand Break ◽  
Foreign Dna ◽  
Dna Strand

Transformation frequencies were measured in CHO mutant EM9 after transfection with intact or modified plasmid pSV2-gpt. The mutant and wild-type strain behaved similarly under all conditions except when homologous recombination was required to produce an intact plasmid. Therefore, the defect of the mutant which renders it slow in DNA strand break rejoining and high in sister chromatid exchange induction reduces its ability to recombine foreign DNA molecules.

scholarly journals Disruption of the Candida albicans TPS1Gene Encoding Trehalose-6-Phosphate Synthase Impairs Formation of Hyphae and Decreases Infectivity

1998 ◽  
Vol 180 (15) ◽  
pp. 3809-3815 ◽  
Author(s):  
Oscar Zaragoza ◽  
Miguel A. Blazquez ◽  
Carlos Gancedo
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Type Strain ◽  
Wild Type Strain ◽  
Calf Serum ◽  
Sugar Metabolism ◽  
Functional Complementation ◽  
Wild Type ◽  
Growth Defects ◽  
Phosphate Synthase

ABSTRACT The TPS1 gene from Candida albicans, which encodes trehalose-6-phosphate synthase, has been cloned by functional complementation of a tps1 mutant from Saccharomyces cerevisiae. In contrast with the wild-type strain, the doubletps1/tps1 disruptant did not accumulate trehalose at stationary phase or after heat shock. Growth of thetps1/tps1 disruptant at 30°C was indistinguishable from that of the wild type. However, at 42°C it did not grow on glucose or fructose but grew normally on galactose or glycerol. At 37°C, the yeast-hypha transition in the mutant in glucose-calf serum medium did not occur. During growth at 42°C, the mutant did not form hyphae in galactose or in glycerol. Some of the growth defects observed may be traced to an unbalanced sugar metabolism that reduces the cellular content of ATP. Mice inoculated with 106 CFU of thetps1/tps1 mutant did not show visible symptoms of infection 16 days after inoculation, while those similarly inoculated with wild-type cells were dead 12 days after inoculation.

Genetics of fungicide resistance in Talaromyces flavus

1984 ◽  
Vol 30 (8) ◽  
pp. 1079-1087 ◽  
Author(s):  
Talma Katan ◽  
M. T. Dunn ◽  
G. C. Papavizas
Keyword(s):  
Effective Dose ◽  
Fungicide Resistance ◽  
Type Strain ◽  
Wild Type Strain ◽  
Slow Growth ◽  
Wild Type ◽  
Osmotic Sensitivity ◽  
Benomyl Resistance ◽  
Talaromyces Flavus ◽  
Dicarboximide Resistance

Three mutants resistant to the fungicide benomyl and two resistant to dicarboximides were developed from a wild-type strain of Talaromyces flavus. Based on sensitivity of various isolates to benomyl concentrations, two levels of resistance were recognized. One isolate with low resistance (LR) was resistant to 5 μg/mL, but sensitive to 50 μg/mL benomyl; and two highly resistant (HR) isolates grew uninhibited at 50 μg/mL. Crosses between resistant isolates and sensitive wild types, as well as between different resistant isolates, showed that the two levels of benomyl resistance are conferred by different alleles at a single locus. The LR allele pleiotropically brings about slow growth. The dicarboximide-resistant isolates were little affected (mean effective dose (ED50) > 250 μg/mL) by iprodione, vinclozolin, dichlozolinate, or Co 6054. Crosses showed that the two dicarboximide-resistant isolates carry allelic mutations that can be characterized by the level of osmotic sensitivity pleiotropically conditioned by them. Dicarboximide resistance was not linked to benomyl resistance.

The Critical Role of Polyketide Synthase Gene On The Swainsonine Biosynthesis in The Fungus Metarhizium Anisopliae

2021 ◽  
Author(s):  
Lu Sun ◽  
Enxia Huang ◽  
Yu Zhang ◽  
Ziyu Guo ◽  
Kexin Wu ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Metarhizium Anisopliae ◽  
Type Strain ◽  
Polyketide Synthase ◽  
Wild Type Strain ◽  
Biosynthesis Pathway ◽  
Wild Type ◽  
Knock Out ◽  
Polyketide Synthase Gene

Abstract Swainsonine (SW) is the principal toxic ingredient of locoweeds, and is produced by fungi including Metarhizium anisopliae, Slafractonia leguminicola, and Alternaria oxytropis. While the SW biosynthesis pathway of fungi and the catalytic enzyme genes that regulate synthesis are not cleanly. In this study, we used homologous recombination (HR) to knock out and interfere with the polyketide synthase gene (pks) of M. anisopliae to determine its effect on the SW biosynthesis pathway. The concentration of SW was measured in the fermentation broth of M. anisopliae at 1 d, 2 d, 3 d, 4 d, 5 d, 6 d or 7 d using LC-MS. The gene for the pks gene was detected by RT-qPCR. Day 5 of M. anisopliae gave the highest content of SW and the highest expression of the pks gene. To determine the role of the pks gene in the SW biosynthesis pathway of M. anisopliae, we used PEG-mediated homologous recombination (HR) to transform a wild-type strain (WT) with a Benomyl (ben)-resistant fragment to knock out the pks gene producing a mutant-type strain (MT) and used PEG-mediated RNAi to transform a wild-type strain (WT) with a Benomyl (ben)-resistant plasmid to interfere with the pks gene. A complemented-type (CT) strain was produced by adding a complementation vector that contains the geneticin (G418) resistance gene as a marker. The content of SW didn’t detected in MT strain, and returned to the original level in the CT strain, while the content of SW was significantly decreased in RNAi strain. We suggest that mutation and RNAi in the pks gene affect the cell wall formation of M. anisopliae, while the colony diameters, phenotypes, and growth rates did not change significantly, and no obvious changes in other cellular organelles were noted. These results indicate that the pks gene plays a crucial role in the SW biosynthesis of M. anisopliae, which provides an important theoretical basis for illuminating the SW biosynthesis and solving locoism in livestock.

scholarly journals Recombination and ligation of transfected DNA in CHO mutant EM9, which has high levels of sister chromatid exchange.

1987 ◽  
Vol 7 (5) ◽  
pp. 2007-2011 ◽  
Author(s):  
C A Hoy ◽  
J C Fuscoe ◽  
L H Thompson
Keyword(s):  
Homologous Recombination ◽  
Sister Chromatid ◽  
Sister Chromatid Exchange ◽  
Type Strain ◽  
Wild Type Strain ◽  
Strand Break ◽  
Wild Type ◽  
Dna Strand Break ◽  
Foreign Dna ◽  
Dna Strand

Transformation frequencies were measured in CHO mutant EM9 after transfection with intact or modified plasmid pSV2-gpt. The mutant and wild-type strain behaved similarly under all conditions except when homologous recombination was required to produce an intact plasmid. Therefore, the defect of the mutant which renders it slow in DNA strand break rejoining and high in sister chromatid exchange induction reduces its ability to recombine foreign DNA molecules.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Mab_3083c Is a Homologue of RNase J and Plays a Role in Colony Morphotype, Aggregation, and Sliding Motility of Mycobacterium abscessus

2021 ◽  
Vol 9 (4) ◽  
pp. 676
Author(s):  
Ting-Yu Liu ◽  
Sheng-Hui Tsai ◽  
Jenn-Wei Chen ◽  
Yu-Ching Wang ◽  
Shiau-Ting Hu ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Opportunistic Pathogen ◽  
Mycobacterium Abscessus ◽  
Colony Morphology ◽  
Clinical Strain ◽  
Immunocompromised Patients ◽  
Clinical Infection ◽  
Wild Type ◽  
Sliding Motility

Mycobacterium abscessus is an opportunistic pathogen causing human diseases, especially in immunocompromised patients. M. abscessus strains with a rough morphotype are more virulent than those with a smooth morphotype. Morphotype switch may occur during a clinical infection. To investigate the genes involved in colony morphotype switching, we performed transposon mutagenesis in a rough clinical strain of M. abscessus. A morphotype switching mutant (smooth) named mab_3083c::Tn was obtained. This mutant was found to have a lower aggregative ability and a higher sliding motility than the wild type strain. However, its glycopeptidolipid (GPL) content remained the same as those of the wild type. Complementation of the mutant with a functional mab_3083c gene reverted its morphotype back to rough, indicating that mab_3083c is associated with colony morphology of M. abscessus. Bioinformatic analyses showed that mab_3083c has a 75.4% identity in amino acid sequence with the well-characterized ribonuclease J (RNase J) of M. smegmatis (RNase JMsmeg). Complementation of the mutant with the RNase J gene of M. smegmatis also switched its colony morphology from smooth back to rough. These results suggest that Mab_3083c is a homologue of RNase J and involved in regulating M. abscessus colony morphotype switching.

scholarly journals Mutations of folC cause increased susceptibility to sulfamethoxazole in Mycobacterium tuberculosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruiqi Wang ◽  
Kun Li ◽  
Jifang Yu ◽  
Jiaoyu Deng ◽  
Yaokai Chen
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Clinical Isolates ◽  
Aminobenzoic Acid ◽  
Wild Type ◽  
Dihydropteroate Synthase ◽  
Expression Levels ◽  
Encoding Gene ◽  
Increased Susceptibility

AbstractPrevious studies showed that mutation of folC caused decreased expression of the dihydropteroate synthase encoding gene folP2 in Mycobacterium tuberculosis (M. tuberculosis). We speculated that mutation of folC in M. tuberculosis might affect the susceptibility to sulfamethoxazole (SMX). To prove this, 53 clinical isolates with folC mutations were selected and two folC mutants (I43A, I43T) were constructed based on M. tuberculosis H37Ra. The results showed that 42 of the 53 clinical isolates (79.2%) and the two lab-constructed folC mutants were more sensitive to SMX. To probe the mechanism by which folC mutations make M. tuberculosis more sensitive to SMX, folP2 was deleted in H37Ra, and expression levels of folP2 were compared between H37Ra and the two folC mutants. Although deletion of folP2 resulted in increased susceptibility to SMX, no difference in folP2 expression was observed. Furthermore, production levels of para-aminobenzoic acid (pABA) were compared between the folC mutants and the wild-type strain, and results showed that folC mutation resulted in decreased production of pABA. Taken together, we show that folC mutation leads to decreased production of pABA in M. tuberculosis and thus affects its susceptibility to SMX, which broadens our understanding of mechanisms of susceptibilities to antifolates in this bacterium.

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