scholarly journals Interactions between QnrB, QnrB Mutants, and DNA Gyrase

2015 ◽  
Vol 59 (9) ◽  
pp. 5413-5419 ◽  
Author(s):  
Eu Suk Kim ◽  
Chunhui Chen ◽  
Molly Braun ◽  
Hyo Youl Kim ◽  
Ryo Okumura ◽  
...  
Keyword(s):  
No Reduction ◽  
Substantial Reduction ◽  
Dna Gyrase ◽  
Single Amino Acid ◽  
Physical Interaction ◽  
Wild Type ◽  
Physical Interactions ◽  
Substitution Mutant ◽  
Two Hybrid ◽  
Intermediate Effect

ABSTRACTPlasmid-encoded protein QnrB1 protects DNA gyrase from ciprofloxacin inhibition. Using a bacterial two-hybrid system, we evaluated the physical interactions between wild-type and mutant QnrB1, the GyrA and GyrB gyrase subunits, and a GyrBA fusion protein. The interaction of QnrB1 with GyrB and GyrBA was approximately 10-fold higher than that with GyrA, suggesting that domains of GyrB are important for stabilizing QnrB1 interaction with the holoenzyme. Sub-MICs of ciprofloxacin or nalidixic acid reduced the interactions between QnrB1 and GyrA or GyrBA but produced no reduction in the interaction with GyrB or a quinolone-resistant GyrA:S83L (GyrA with S83L substitution) mutant, suggesting that quinolones and QnrB1 compete for binding to gyrase. Of QnrB1 mutants that reduced quinolone resistance, deletions in the C or N terminus of QnrB1 resulted in a marked decrease in interactions with GyrA but limited or no effect on interactions with GyrB and an intermediate effect on interactions with GyrBA. While deletion of loop B and both loops moderately reduced the interaction signal with GyrA, deletion of loop A resulted in only a small reduction in the interaction with GyrB. The loop A deletion also caused a substantial reduction in interaction with GyrBA, with little effect of loop B and dual-loop deletions. Single-amino-acid loop mutations had little effect on physical interactions except for a Δ105I mutant. Therefore, loops A and B may play key roles in the proper positioning of QnrB1 rather than as determinants of the physical interaction of QnrB1 with gyrase.

The autophagy genes ChATG4 and ChATG8 are required for reproductive development, virulence, and septin assembly in Cochliobolus heterostrophus

2021 ◽  
Author(s):  
Huilin Yu ◽  
Wantong Jia ◽  
Kunqin Xiao ◽  
Wenli Jiao ◽  
Xianghui Zhang ◽  
...  
Keyword(s):  
Wild Type Strain ◽  
Fungal Growth ◽  
Reproductive Development ◽  
Gene Replacement ◽  
Cochliobolus Heterostrophus ◽  
Physical Interaction ◽  
Wild Type ◽  
Yeast Two Hybrid ◽  
Growth Development ◽  
Two Hybrid

Autophagy is a highly conserved degrading process and is crucial for cell growth and development in eukaryotes, especially when they face starvation and stressful conditions. To evaluate the functions of Atg4 and Atg8 in mycelial growth, asexual and sexual development, and virulence in Cochliobolus heterostrophus, ΔChatg4 and ΔChatg8 mutants were generated by gene replacement. Strains deleted for ChATG4 and ChATG8 genes showed significant changes in vegetative growth and in development of conidia and ascospores compared with the wild-type strain. The autophagy process was blocked and the virulence was reduced dramatically in ΔChatg4 and ΔChatg8 mutants. In addition, deletion of ChATG4 and ChATG8 disordered Cdc10 subcellular localization and formation of septin rings. The direct physical interaction between ChAtg4 and ChAtg8 was detected by Yeast-two-hybrid, and ChAtg4-GFP was dispersed throughout the cytoplasm, although GFP-ChAtg8 appeared as punctate structures. All phenotypes were restored in complemented strains. Taken together, these findings indicated that ChATG4 and ChATG8 were crucial for autophagy to regulate fungal growth, development, virulence, and localization of septin in C. heterostrophus.

scholarly journals Interaction between NifL and NifA in the nitrogen-fixing Pseudomonas stutzeri A1501

Microbiology ◽  
2006 ◽  
Vol 152 (12) ◽  
pp. 3535-3542 ◽  
Author(s):  
Zhihong Xie ◽  
Yuetang Dou ◽  
Shuzheng Ping ◽  
Ming Chen ◽  
Guoying Wang ◽  
...  
Keyword(s):  
Nitrogenase Activity ◽  
Pseudomonas Stutzeri ◽  
Physical Interaction ◽  
Wild Type ◽  
Yeast Two Hybrid ◽  
Free Living ◽  
Yeast Two Hybrid System ◽  
Living State ◽  
Microaerobic Conditions ◽  
Two Hybrid

Pseudomonas stutzeri strain A1501 isolated from rice fixes nitrogen under microaerobic conditions in the free-living state. This paper describes the properties of nifL and nifA mutants as well as the physical interaction between NifL and NifA proteins. A nifL mutant strain that carried a mutation non-polar on nifA expression retained nitrogenase activity. Complementation with a plasmid containing only nifL led to a decrease in nitrogenase activity in both the wild-type and the nifL mutant, suggesting that NifL acts as an antiactivator of NifA activity. Using the yeast two-hybrid system and purified protein domains of NifA and NifL, an interaction was shown between the C-terminal domain of NifL and the central domain of NifA, suggesting that NifL antiactivator activity is mediated by direct protein interaction with NifA.

Crystal engineering: a case study using the 24 kDa fragment of the DNA gyrase B subunit from Escherichia coli

1999 ◽  
Vol 55 (9) ◽  
pp. 1623-1625 ◽  
Author(s):  
Allan D'Arcy ◽  
Martine Stihle ◽  
Dirk Kostrewa ◽  
Glenn Dale
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Crystal Engineering ◽  
Dna Gyrase ◽  
Site Directed Mutagenesis ◽  
Crystal Quality ◽  
Single Amino Acid ◽  
Wild Type ◽  
B Subunit

Site-directed mutagenesis was used to determine the efficacy of changing surface residues to improve crystal quality. Nine mutants of the 24 kDa fragment of the Escherichia coli DNA gyrase B subunit were produced, changing residues on the protein's surface. The mutations changed either the charge or the polarity of the wild-type amino acid. It was found that single amino-acid changes on the surface could have a dramatic effect on the crystallization properties of the protein and generally resulted in an improvement in the number of crystal-screen hits as well as an improvement in crystal quality. It is concluded that crystal engineering is a valuable tool for protein crystallography.

scholarly journals Sensitivity of human immunodeficiency virus to bicyclam derivatives is influenced by the three-dimensional structure of gp120.

1997 ◽  
Vol 41 (12) ◽  
pp. 2616-2620 ◽  
Author(s):  
K De Vreese ◽  
I Van Nerum ◽  
K Vermeire ◽  
J Anné ◽  
E De Clercq
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Single Amino Acid ◽  
Resistance Pattern ◽  
V3 Loop ◽  
Resistant Virus ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Resistant Strains ◽  
Anti Hiv

The bicyclams are a new class of anti-human immunodeficiency virus (anti-HIV) compounds targeted at viral entry. From marker rescue experiments, it appears that the envelope gp120 glycoprotein plays an important role in the anti-HIV activity of the bicyclams. Bicyclam-resistant strains contain a number of amino acid changes scattered over the V2 to V5 region of gp120. Experiments aimed at estimating the relative importance of particular amino acid changes with regard to the overall resistance pattern are described. The sequences of some partially bicyclam-resistant virus strains, obtained during the resistance development process, were analyzed, and the corresponding 50% effective concentrations were determined. Selected mutations observed in bicyclam-resistant strains were introduced in the wild-type background by site-directed mutagenesis. In addition, some amino acids were back-mutated to their wild-type counterparts in an otherwise JM3100-resistant strain. The sensitivities of these mutant viruses to bicyclams were determined. Construction of chimeric viruses, carrying the V3 loop of JM3100-resistant virus in a wild-type HIV type 1 HXB2 background, enabled us to investigate the importance of the mutations in the V3 loop of JM3100-resistant virus. From the results described in the report, it can be concluded that single amino acid substitutions do not influence the observed resistance to JM3100. Also, the mutations in the V3 loop are not sufficient to engender even a partially resistant phenotype. We postulate that the overall conformation of gp120 determines the degree of sensitivity or resistance of HIV strains to bicyclams.

scholarly journals Enhancement of the Efficiency of Secretion of Heterologous Lipase in Escherichia coli by Directed Evolution of the ABC Transporter System

2005 ◽  
Vol 71 (7) ◽  
pp. 3468-3474 ◽  
Author(s):  
Gyeong Tae Eom ◽  
Jae Kwang Song ◽  
Jung Hoon Ahn ◽  
Yeon Soo Seo ◽  
Joon Shick Rhee
Keyword(s):  
Escherichia Coli ◽  
Directed Evolution ◽  
Abc Transporter ◽  
Microtiter Plate ◽  
Single Amino Acid ◽  
Wild Type ◽  
E Coli ◽  
Single Amino Acid Change ◽  
Secretion Efficiency

ABSTRACT The ABC transporter (TliDEF) from Pseudomonas fluorescens SIK W1, which mediated the secretion of a thermostable lipase (TliA) into the extracellular space in Escherichia coli, was engineered using directed evolution (error-prone PCR) to improve its secretion efficiency. TliD mutants with increased secretion efficiency were identified by coexpressing the mutated tliD library with the wild-type tliA lipase in E. coli and by screening the library with a tributyrin-emulsified indicator plate assay and a microtiter plate-based assay. Four selected mutants from one round of error-prone PCR mutagenesis, T6, T8, T24, and T35, showed 3.2-, 2.6-, 2.9-, and 3.0-fold increases in the level of secretion of TliA lipase, respectively, but had almost the same level of expression of TliD in the membrane as the strain with the wild-type TliDEF transporter. These results indicated that the improved secretion of TliA lipase was mediated by the transporter mutations. Each mutant had a single amino acid change in the predicted cytoplasmic regions in the membrane domain of TliD, implying that the corresponding region of TliD was important for the improved and successful secretion of the target protein. We therefore concluded that the efficiency of secretion of a heterologous protein in E. coli can be enhanced by in vitro engineering of the ABC transporter.

Mutation of a single amino acid converts the human water channel aquaporin 5 into an anion channel

2013 ◽  
Vol 305 (6) ◽  
pp. C663-C672 ◽  
Author(s):  
Xue Qin ◽  
Walter F. Boron
Keyword(s):  
Water Channel ◽  
Anion Channel ◽  
Single Amino Acid ◽  
Side Chain ◽  
Wild Type ◽  
Aquaporin 5 ◽  
Anion Conductance ◽  
Electrode Voltage ◽  
Microelectrode Measurements ◽  
Positively Charged

Aquaporin 6 (AQP6) is unique among mammalian AQPs in being an anion channel with negligible water permeability. However, the point mutation Asn60Gly converts AQP6 from an anion channel into a water channel. In the present study of human AQP5, we mutated Leu51 (corresponding to residue 61 in AQP6), the side chain of which faces the central pore. We evaluated function in Xenopus oocytes by two-electrode voltage clamp, video measurements of osmotic H2O permeability ( Pf), microelectrode measurements of surface pH (pHS) to assess CO2 permeability, and surface biotinylation. We found that AQP5-L51R does not exhibit the H2O or CO2 permeability of the wild-type protein but instead has a novel p-chloromercuribenzene sulfonate (pCMBS)-sensitive current. The double mutant AQP5-L51R/C182S renders the conductance insensitive to pCMBS, demonstrating that the current is intrinsic to AQP5. AQP5-L51R has the anion permeability sequence I− > NO3− ≅ NO2− > Br− > Cl− > HCO3− > gluconate. Of the other L51 mutants, L51T (polar uncharged) and L51V (nonpolar) retain H2O and CO2 permeability and do not exhibit anion conductance. L51D and L51E (negatively charged) have no H2O or CO2 permeability. L51K (positively charged) has an intermediate H2O and CO2 permeability and anion conductance. L51H is unusual in having a relatively low CO2 permeability and anion conductance, but a moderate Pf. Thus, positively charged mutations of L51 can convert AQP5 from a H2O/CO2 channel into an anion channel. However, the paradoxical effect of L51H is consistent with the hypothesis that CO2, in part, takes a pathway different from H2O through AQP5.

scholarly journals The manifold actions of the protein inhibitor of activated STAT proteins on the transcriptional activity of mineralocorticoid and glucocorticoid receptors in neural cells

2004 ◽  
Vol 32 (3) ◽  
pp. 825-841 ◽  
Author(s):  
M Tirard ◽  
J Jasbinsek ◽  
OF Almeida ◽  
TM Michaelidis
Keyword(s):  
Transcriptional Activity ◽  
Glucocorticoid Receptors ◽  
Specific Interaction ◽  
Human Neuroblastoma Cell ◽  
Physical Interaction ◽  
Neural Cells ◽  
Protein Inhibitor ◽  
Human Neuroblastoma ◽  
The Brain ◽  
Two Hybrid

Corticosteroid actions in the brain are exerted via the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). These receptors share several structural and functional similarities but their activation in the brain triggers distinct biological actions, for instance on neuronal survival or the regulation of the hypothalamo-pituitary-adrenal axis. Like other hormone-activated receptors, the transcriptional properties of the MR and GR depend on their ability to recruit a variety of co-regulators, which modulate their activity on target promoters, in a specific manner. The N-terminal regions of the MR and GR share the smallest degree of sequence conservation, whereas they display opposite effects on the transactivation properties of these receptors; thus, they may provide surfaces suitable for receptorspecific interactions with co-regulatory proteins. Here, we employed a yeast two-hybrid system to identify molecules interacting with the N-terminal part of the MR (amino acids 170-433). This approach resulted in the isolation of representative cDNAs from all members of the protein inhibitor of activated STAT (PIAS) family of proteins as potential MR-interacting partners. In neural cells, PIAS3 exhibited a strong and specific interaction with MR, but not GR, as indicated by mammalian two-hybrid assays and co-immunoprecipitation experiments in vivo. The interaction with MR was enhanced in the presence of aldosterone, an MR agonist, and was found to occur through a conserved, serine- and acidic amino acid residue-rich domain of PIAS3. To compare the modulatory properties of PIAS proteins on MR and GR transcriptional activity in a neural environment, MMTV reporter gene assays were performed in the human neuroblastoma cell line SK-N-MC. This analysis revealed that PIAS3 can inhibit MR, but not GR, transactivation in response to their corresponding ligands. Further, it showed that PIAS1 and PIASxbeta, but not PIASy, could also inhibit MR-mediated transcription despite the lack of detected physical interaction with MR. Interestingly, PIASxbeta and PIASy dose-dependently co-activated GR, whereas PIAS1 impaired GR-induced transcription. Taken together the results reveal differential modulatory roles of the PIAS proteins on the transcriptional properties of MR and GR, thus providing new insights into the bifurcating actions of these two receptors in neural cells where they are frequently co-localized.

scholarly journals Subunit Interactions in the mariner Transposase

Genetics ◽  
1996 ◽  
Vol 144 (3) ◽  
pp. 1087-1095 ◽  
Author(s):  
Allan R Lohe ◽  
David T Sullivan ◽  
Daniel L Hartl
Keyword(s):  
Hybrid System ◽  
Catalytic Domain ◽  
Wild Type ◽  
Target Element ◽  
Yeast Two Hybrid ◽  
Subunit Interactions ◽  
Hsp70 Promoter ◽  
Yeast Two Hybrid System ◽  
Transposition Reaction ◽  
Two Hybrid

Abstract We have studied the Mos1 transposase encoded by the transposable element mariner. This transposase is a member of the “D,D(35)E” superfamily of proteins exhibiting the motif D,D(34)D. It is not known whether this transposase, or other eukaryote transposases manifesting the D,D(35)E domain, functions in a multimeric form. Evidence for oligomerization was found in the negative complementation of Mos1 by an EMS-induced transposase mutation in the catalytic domain. The transposase produced by this mutation has a glycine-to-arginine replacement at position 292. The G292R mutation strongly interferes with the ability of wild-type transposase to catalyze excision of a target element. Negative complementation was also observed for two other EMS mutations, although the effect was weaker than observed with G292R. Results from the yeast two-hybrid system also imply that Mos1 subunits interact, suggesting the possibility of subunit oligomerization in the transposition reaction. Overproduction of Mos1 subunits through an hsp70 promoter also inhibits excision of the target element, possibly through autoregulatory feedback on transcription or through formation of inactive or less active oligomers. The effects of both negative complementation and overproduction may contribute to the regulation of mariner transposition.

Tetramer formation of Bacillus subtilis YabJ protein that belongs to YjgF/YER057c/UK114 family

2021 ◽  
Vol 85 (2) ◽  
pp. 297-306
Author(s):  
Zui Fujimoto ◽  
Le Thi Thu Hong ◽  
Naomi Kishine ◽  
Nobuhiro Suzuki ◽  
Keitarou Kimura
Keyword(s):  
Bacillus Subtilis ◽  
Quaternary Structure ◽  
Single Amino Acid ◽  
Wild Type ◽  
Amino Acid Mutation ◽  
X Ray Crystallography ◽  
Ligand Binding Sites ◽  
Potential Ligand ◽  
Single Amino Acid Mutation

ABSTRACT Bacillus subtilis YabJ protein belongs to the highly conserved YjgF/YER057c/UK114 family, which has a homotrimeric quaternary structure. The dominant allele of yabJ gene that is caused by a single amino acid mutation of Ser103Phe enables poly-γ-glutamic acid (γPGA) production of B. subtilis under conditions where the cell-density signal transduction was disturbed by the loss of DegQ function. X-ray crystallography of recombinant proteins revealed that unlike the homotrimeric wild-type YabJ, the mutant YabJ(Ser103Phe) had a homotetrameric quaternary structure, and the structural change appeared to be triggered by an inversion of the fifth β-strand. The YabJ homotetramer has a hole that is highly accessible, penetrating through the tetramer, and 2 surface concaves as potential ligand-binding sites. Western blot analyses revealed that the conformational change was also induced in vivo by the Ser103Phe mutation.

Sign in / Sign up

Export Citation Format

Share Document