ABSTRACT
A gene, mokA, encoding a protein with similarities to histidine kinase-response regulator hybrid sensor, was cloned from a Myxococcus xanthus genomic library. The predicted mokA gene product was found to contain three domains: an amino-terminal input domain, a central transmitter domain, and a carboxy-terminal receiver domain. mokA mutants placed under starvation conditions exhibited reduced sporulation. Mutation of mokA also caused marked growth retardation at high osmolarity. These results indicated that M. xanthus MokA is likely a transmembrane sensor that is required for development and osmotic tolerance. The putative function of MokA is similar to that of the hybrid histidine kinase, DokA, of the eukaryotic slime mold Dictyostelium discoideum.
Subject(s)
Bacterial Proteins/genetics , Membrane Proteins/genetics , Myxococcus xanthus/genetics , Osmotic Pressure , Signal Transduction/genetics , Amino Acid Sequence , Base Sequence , Cloning, Molecular , Genes, Bacterial , Molecular Sequence Data , Mutagenesis , Myxococcus xanthus/drug effects , Protein Structure, Tertiary , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Sodium Chloride/pharmacologyABSTRACT
The mac-1 gene of Myxococcus xanthus TA, an antibiotic TA producer, encoded a protein with strong sequence similarity to the antibiotic ATP-binding cassette (ABC) transporter for macrolide antibiotics. The mac-1 gene encoding protein (Mac-1) had two ATP-binding domains containing Walker A and B motifs, and no hydrophobic transmembrane regions. Insertional inactivation of mac-1 caused enhanced sensitivity to oleandomycin, a macrolide antibiotic, while the mac-1 mutant showed normal export of antibiotic TA into the extracellular fluid. The mac-1 mutant could form mounds, but was unable to form fruiting bodies or sporulate under nutrient starvation. A primary role for Mac-1 in M. xanthus may be as a transporter which exports or imports a molecule required for the sporulation process.
Subject(s)
ATP-Binding Cassette Transporters/genetics , Myxococcus xanthus/genetics , ATP-Binding Cassette Transporters/chemistry , ATP-Binding Cassette Transporters/metabolism , Adenosine Triphosphate/metabolism , Amino Acid Motifs , Amino Acid Sequence , Anti-Bacterial Agents/metabolism , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Base Sequence , Binding Sites , Biological Transport , Cloning, Molecular , Genes, Bacterial/genetics , Macrolides , Microbial Sensitivity Tests , Molecular Sequence Data , Myxococcus xanthus/drug effects , Myxococcus xanthus/growth & development , Myxococcus xanthus/metabolism , Oleandomycin/pharmacology , Point Mutation/genetics , Protein Structure, Tertiary , RNA, Bacterial/genetics , RNA, Bacterial/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Alignment , Spores, Bacterial/physiology , Structure-Activity RelationshipABSTRACT
Hydroquinone (HQ) dose-dependently reduced the viable cell number of oral tumor cell lines (HSC-2, HSG). HQ induced internucleosomal DNA fragmentation in human promyelocytic leukemic HL-60 cells, but not in HSC-2 nor HSG cells. Cytotoxic activity of HQ was slightly reduced by catalase, but was enhanced by superoxide dismutase, suggesting the possible involvement of hydrogen peroxide in HQ-induced cytotoxicity. This was supported by slight increase or decrease of cytotoxicity of HQ in the presence of Cu2+ and Fe3+, respectively. Lower concentrations of sodium ascorbate, ascorbic acid and ascorbic acid 6-palmitate reduced both the radical intensity and cytotoxic activity of HQ, more efficiently than ascorbic acid 2,6-dipalmitate, in contrast to the cytotoxic action of these ascorbates at higher (millimolar) concentrations. Popular antioxidants such as N-acetyl-L-cysteine and cysteine also reduced the radical intensity and cytotoxic activity of HQ. The present study suggests that cytotoxic activity of HQ is generated by radical-mediated oxidation mechanism.
Subject(s)
Antioxidants/pharmacology , Hydroquinones/toxicity , Mutagens/toxicity , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Catalase/pharmacology , Cell Survival/drug effects , DNA Damage , Drug Interactions , Electron Spin Resonance Spectroscopy , Free Radicals/antagonists & inhibitors , Free Radicals/metabolism , Free Radicals/toxicity , HL-60 Cells/drug effects , Humans , Hydrogen-Ion Concentration , Hydroquinones/antagonists & inhibitors , Hydroquinones/metabolism , Mouth Neoplasms/metabolism , Mouth Neoplasms/pathology , Mutagens/metabolism , Salivary Gland Neoplasms/metabolism , Salivary Gland Neoplasms/pathology , Superoxide Dismutase/pharmacology , Tumor Cells, Cultured/drug effectsABSTRACT
PURPOSE: To report the results of vitrectomy and intraocular lens (IOL) removal for the treatment of endophthalmitis after IOL implantation. METHODS: We reviewed 14 eyes of 14 patients who underwent pars plana vitrectomy because of postoperative endophthalmitis. Culture results, surgical methods, and visual outcome are presented. RESULTS: The cultures grew Enterococcus faecalis (n = 3), Staphylococcus epidermidis (n = 2), Propionibacterium acnes (n = 1), and gram-negative bacillus (n = 3). The eyes infected with E. faecalis had poor visual outcome. Eleven eyes treated by the combination of pars plana vitrectomy and IOL removal did not have a recurrence. The remaining 3 eyes on which only vitrectomy was performed had a recurrence, and the additional procedures consisting of vitrectomy and IOL removal could result in eradicating endophthalmitis. CONCLUSIONS: A higher rate of E. faecalis was detected and these eyes had severe inflammation and poor visual outcome. Combined vitrectomy and IOL removal may be a more certain method to prevent recurrence.
Subject(s)
Endophthalmitis/surgery , Eye Infections, Bacterial/surgery , Lens Implantation, Intraocular/adverse effects , Vitrectomy , Aged , Aged, 80 and over , Device Removal , Endophthalmitis/etiology , Endophthalmitis/microbiology , Enterococcus faecalis/isolation & purification , Eye Infections, Bacterial/etiology , Eye Infections, Bacterial/microbiology , Female , Gram-Negative Bacterial Infections/etiology , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/surgery , Gram-Positive Bacterial Infections/etiology , Gram-Positive Bacterial Infections/microbiology , Gram-Positive Bacterial Infections/surgery , Humans , Lenses, Intraocular/adverse effects , Lenses, Intraocular/microbiology , Male , Middle Aged , Propionibacterium acnes/isolation & purification , Reoperation , Retrospective Studies , Staphylococcal Infections/etiology , Staphylococcal Infections/microbiology , Staphylococcal Infections/surgery , Staphylococcus epidermidis/isolation & purification , Visual AcuityABSTRACT
The interaction between hydroquinone (HQ) and ascorbic acid analogs was investigated. Semiquinone radicals (SQ.) generated by HQ were comparably scavenged by ascorbic acid, sodium ascorbate and ascorbate 6-palmitate, but much less efficiently by ascorbate 2,6-dipalmitate. Organic solvents, such as dimethysulfoxide (DMSO) or ethanol, which are utilized for solubilization of water-insoluble analogs, ascorbate 6-palmitate and ascorbate 2,6-dipalmitate, also scavenged SQ.. DMSO scavenged the SQ. more efficiently than ethanol. This suggests the importance of considering such a quenching effect of organic solvent in the study of the interaction between HQ and antioxidants. The involvement of the ascorbate radical for cytotoxicity induction is discussed.
Subject(s)
Ascorbic Acid/analogs & derivatives , Ascorbic Acid/chemistry , Hydroquinones/chemistry , Benzoquinones/chemistry , Dimethyl Sulfoxide/chemistry , Drug Interactions , Electron Spin Resonance Spectroscopy/methods , Ethanol/chemistry , Free Radicals/chemistry , Hydrogen-Ion Concentration , SolventsABSTRACT
Dopamine dose-dependently reduced the viable cell number of both human salivary gland tumor HSG and oral squamous cell carcinoma HSC-2, HSC-4, and NA cells. CoCl2 significantly reduced both the cytotoxic activity and radical intensity of dopamine (determined by ESR spectroscopy). Dopamine produced DNA fragments (demonstrated by TUNEL method) and induced degradation of cytokeratin by activated caspase in HSG cells (detected by an immunocytochemical method, using a specific M30 monoclonal antibody). FACS analysis demonstrated that dopamine induced DNA fragmentation, a biochemical hallmark of apoptosis, in human promyelocytic leukemia HL-60 cells. The addition of catalase did not prevent the apoptosis-inducing activity of dopamine, reducing the possibility of the involvement of H2O2 for dopamine-induced apoptosis. Dopamine transiently induced p38 mitogen-activated protein kinase (MAP kinase) phosphorylation. However, an inhibitor of p38 MAP kinase phosphorylation, SB203680, failed to inhibit the dopamine-induced apoptosis. These data suggest that p38 phosphorylation at an early stage may not be a causative event for apoptosis.
