scholarly journals Effect of phosphate levels on the synthesis of acid phosphatases (EC 3.1.3.2) inNeurospora crassa

1985 ◽  
Vol 45 (3) ◽  
pp. 239-249 ◽  
Author(s):  
Sergio A. Rodrigues ◽  
Antonio Rossi
Keyword(s):  
Molecular Weight ◽  
Type Strain ◽  
Wild Type Strain ◽  
Deae Cellulose ◽  
Phosphate Starvation ◽  
Acid Phosphatases ◽  
Wild Type ◽  
Specific Activities ◽  
Phosphate Medium ◽  
High Phosphate

SummaryWhen grown on high-phosphate medium, the wild-type strain 74A ofN. crassasynthesized two acid phosphatases, as shown by DEAE -cellulose chromatography. These purified enzymes showed heterogeneity on PAGE, low specific activities towards PNP-P, molecular weight values of at least 300000, no deviation from Michaelian behaviour, and great stability in 50 mM sodium acetate buffer, at pH 5·4, when kept at 54 °C. These acid phosphatases were synthesized in reduced amounts or not at all when the mould was grown under conditions of phosphate starvation, indicating that the level of phosphate also regulates the synthesis of the high molecular weight enzyme forms. When grown on high phosphate medium, thepho-3mutant strain also synthesized two acid phosphatases, whose purified enzymes showed no pronounced differences when compared to those synthesized by the wild-type strain in terms of electrophoretic analysis, specific activities towards PNP-P, molecular weight values, and Michaelian behaviour. However, one enzyme form had a higherKmvalue and a lower heat stability than the corresponding enzyme of the wild-type strain. Even though thepho-3locus might not be responsible for an alteration in the primary structure of the repressible acid phosphatase, it seems clear that the enzymes synthesized by the mould grown on low-or high-phosphate medium must share some structural features. Thus, the drastic differences observed in the molecular properties of the enzymes synthesized by the mould grown under conditions of phosphate starvation as opposed to phosphate repression might be due to an effect exerted by the level of inorganic phosphate in regulating the translation, post-translational modifications and/or excretion, but not necessarily the gene-directed synthesis of distinct mRNAs.

scholarly journals Environmental Regulation of Exopolysaccharide Production in Sinorhizobium meliloti

2000 ◽  
Vol 182 (3) ◽  
pp. 599-606 ◽  
Author(s):  
Kiprian E. Mendrygal ◽  
Juan E. González
Keyword(s):  
Molecular Weight ◽  
Type Strain ◽  
Sinorhizobium Meliloti ◽  
Wild Type Strain ◽  
Root Nodules ◽  
Weight Fraction ◽  
Wild Type ◽  
Exopolysaccharide Production ◽  
Successful Establishment ◽  
High Phosphate

ABSTRACT Exopolysaccharide production by Sinorhizobium melilotiis required for invasion of root nodules on alfalfa and successful establishment of a nitrogen-fixing symbiosis between the two partners.S. meliloti wild-type strain Rm1021 requires production of either succinoglycan, a polymer of repeating octasaccharide subunits, or EPS II, an exopolysaccharide of repeating dimer subunits. The reason for the production of two functional exopolysaccharides is not clear. Earlier reports suggested that low-phosphate conditions stimulate the production of EPS II in Rm1021. We found that phosphate concentrations determine which exopolysaccharide is produced by S. meliloti. The low-phosphate conditions normally found in the soil (1 to 10 μM) stimulate EPS II production, while the high-phosphate conditions inside the nodule (20 to 100 mM) block EPS II synthesis and induce the production of succinoglycan. Interestingly, the EPS II produced by S. meliloti in low-phosphate conditions does not allow the invasion of alfalfa nodules. We propose that this invasion phenotype is due to the lack of the active molecular weight fraction of EPS II required for nodule invasion. An analysis of the function of PhoB in this differential exopolysaccharide production is presented.

The phosphoenolpyruvate: sugar phosphotransferase system of Streptococcus salivarius. Identification of a IIIman protein

1987 ◽  
Vol 33 (2) ◽  
pp. 118-122 ◽  
Author(s):  
Christian Vadeboncoeur ◽  
Lucie Gauthier
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Deae Cellulose ◽  
Reaction Medium ◽  
Inhibitory Effect ◽  
Spontaneous Mutant ◽  
Streptococcus Salivarius ◽  
Wild Type ◽  
Phosphotransferase System ◽  
Growth Inhibitory

A double-spontaneous mutant resistant to the growth inhibitory effect of α-methylglucoside and 2-deoxyglucose was isolated from Streptococcus salivarius. This mutant strain, called αS3L11, did not grow on mannose and grew poorly on 5 mM fructose and 5 mM glucose. Isolated membranes of strain αS3L11 were unable to catalyse the phosphoenolpyruvate-dependent phosphorylation of mannose in the presence of purified enzyme I and HPr. Addition of dialysed membrane-free cellular extract of the wild-type strain to the reaction medium restored the activity. The factor that restored the phosphoenolpyruvate–mannose phosphotransferase activity to membranes of strain αS3L11 was called IIIman. This factor was partially purified from the wild-type strain by DEAE-cellulose chromatography, DEAE-TSK chromatography, and molecular seiving on a column of Ultrogel AcA 34. This partially purified preparation also enhanced the phosphoenolpyruvate-dependent phosphorylation of glucose, fructose, and 2-deoxyglucose in strain αS3L11.

Amylase hyper-producing haploid recombinant strains of Thermomyces lanuginosus obtained by intraspecific protoplast fusion

2000 ◽  
Vol 46 (7) ◽  
pp. 669-673 ◽  
Author(s):  
K Rubinder ◽  
B S Chadha ◽  
S Singh ◽  
H S Saini
Keyword(s):  
Protoplast Fusion ◽  
Culture Filtrate ◽  
Catabolite Repression ◽  
Type Strain ◽  
Wild Type Strain ◽  
Thermomyces Lanuginosus ◽  
Wild Type ◽  
Haploid Strain ◽  
Recombinant Strains ◽  
Specific Activities

Amylase hyper-producing, catabolite-repression-resistant, recombinant strains were produced by intraspecific protoplast fusion of thermophilic fungus Thermomyces lanuginosus strains, using well-characterized, morphological, and 2-deoxy-D-glucose resistant markers. The fusant heterokaryons exhibited enhanced amylase activities as compared to the amylase hyper-producing parental strain (T2). Diploids derived from heterokaryons segregated to stable haploid recombinant strains. In the haploid strain (Tlh 4q), approximately 5-fold higher specific activities of α-amylase and glucoamylase in the culture filtrate were observed as compared to the wild-type strain (W0).Key words: Thermomyces lanuginosus, protoplast fusion, amylase hyper-producing strain, catabolite repression.

A Stable 44S Intermediate in the Autodigestion of 50S Ribosomal Subunits

1971 ◽  
Vol 29 ◽  
pp. 430-431
Author(s):  
John H. Nisbet ◽  
Henry S. Slayter
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Ribosomal Rna ◽  
Gel Electrophoresis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Ribosomal Subunit ◽  
Wild Type ◽  
Ribosomal Subunits ◽  
Type Strains

Wild - type strains of Escherichia coli are known to contain as many as four endogenous nucleases (Ref. 1). These are commonly found associated with the ribosomes after extraction from the cell, but may be removed, with the exception of RNase IV, by washing the ribosomes in NH4Cl (at 0.2 M and higher concentrations). We have examined the effect of these nucleases on the 50S ribosomal subunit of one wild-type strain, K12 (Hfr 3000), by incubating the unwashed particles at 37° in the presence of varying magnesium concentrations.At 10-4 molar magnesium (slower at 10-3 molar), the 50S particle is converted to a species sedimenting at about 44S. About 20% of the total O.D260 is liberated at the same time. Continued incubation leads to the release of more O.D260 material while the RNA remaining in the 44S (Fig. 1) particle is progressively cleaved, eventually to the point where it consists of one principal fragment of molecular weight 0.42 x 106 daltons and several lesser fragments. The ribosomal RNA and proteins have been characterized by acrylamide gel electrophoresis.

MenNC1: A PUTATIVE REGULATORY MUTANT OF NADP-MALIC ENZYME IN DROSOPHILA MELANOGASTER

1982 ◽  
Vol 24 (4) ◽  
pp. 409-416 ◽  
Author(s):  
John H. Williamson
Keyword(s):  
Molecular Weight ◽  
Malic Enzyme ◽  
Type Strain ◽  
Wild Type Strain ◽  
Specific Protein ◽  
Activity Levels ◽  
Wild Type ◽  
Type Population ◽  
Temperature Optima ◽  
Substrate Kinetics

MenNC1 was isolated from a wild-type population as a putative NADP-Malic enzyme null-activity mutant. Detailed analysis of this mutant revealed that MenNC1 homozygotes exhibit 3 to 5% of normal levels of NADP-ME activity throughout development. NADP-ME purified from MenNC1 homozygotes is not different from NADP-ME purified from a standard wild-type strain when electrophoretic mobility, molecular weight, substrate kinetics and temperature optima are compared. Quantitative rocket immunoelectrophoresis has demonstrated reduction of NADP-ME-specific protein in MenNC1 homozygotes proportionate to activity levels. It is suggested that MenNC1 may represent a regulatory locus controlling levels of NADP-ME in Drosophila.

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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