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Altered metabolism in cancer cells is suspected to contribute to chemoresistance, but the precise mechanisms are unclear. Here, we show that intracellular ATP levels are a core determinant in the development of acquired cross-drug resistance of human colon cancer cells that harbor different genetic backgrounds. Drug-resistant cells were characterized by(More)
Protein modifications, such as carbonylation, nitration and formation of lipid peroxidation adducts, e.g. 4-hydroxynonenal (HNE), are products of oxidative damage attributed to reactive oxygen species (ROS). The mitochondrial respiratory chain Complexes I and III have been shown to be a major source of ROS in vitro. Additionally, modifications of the(More)
Model studies have identified 16 conserved positively charged amino acids that form a positive strip pointing toward the center hole of Rho. Fourteen residues were individually changed to either an alanine or a glycine and one to a glutamate. Residues Arg(269), Arg(272), Lys(283), Arg(296), Lys(298), and Arg(299) form a subdomain (locus) located N-terminal(More)
Rho transcription termination factor mutant, F355W, showed tryptophan fluorescence intensity approximately twice that of wild-type Rho at equivalent protein concentrations and underwent a decrease in relative fluorescence intensity at 350 nm when 100 microm ATP was added in the presence or absence of RNA. Titration of this fluorescence quenching with(More)
Bicyclomycin is a novel, commercially important antibiotic. Information concerning the site of bicyclomycin inhibition in Escherichia coli has been obtained by the production of bicyclomycin resistant mutants by UV irradiation. Selection by growth in the presence of bicyclomycin of a plasmid clone library generated from a highly resistant mutant in(More)
A sumary of biochemical, biophysical, and molecular biological data is presented which led to the identification of two different polypeptides (α and β, MW=9.16 and 4.27 kDa) in the cytochrome b-559 protein. The presence of a single His residue on each polypeptide, and the conclusion from spectroscopy that the heme coordination must be bis-histidine led to(More)
The amino acid sequences of cytochrome b of complex III from five different mitochondrial sources (human, bovine, mouse, yeast, and Aspergillus nidulans) and the chloroplast cytochrome b6 from spinach show a high degree of homology. Calculation of the distribution of hydrophobic residues with a "hydropathy" function that is conserved in this family of(More)
The interaction of Rho and the antibiotic bicyclomycin was probed using in vitro transcription termination reactions, poly(C) binding assays, limited tryptic digestions, and the bicyclomycin inhibition kinetics of ATPase activity in the presence of poly(dC) and ribo(C)10. The approximate I50 value for the bicyclomycin inhibition of transcription termination(More)
The hydrophobic cytochrome b-559, purified from unstacked, ethanol-washed spinach thylakoid membranes, using extraction with 2% Triton X-100 in 4 M urea and three chromatographic steps in the presence of protease inhibitors, has a dominant band on sodium dodecyl sulfate-urea gels corresponding to Mr = 10,000. The yield of this preparation is 30-50% (5-10(More)
A physical restriction map of the genome of the cyanobacterium Synechococcus sp. strain PCC 7002 was assembled from AscI, NotI, SalI, and SfiI digests of intact genomic DNA separated on a contour-clamped homogeneous electric field pulsed-field gel electrophoresis system. An average genome size of 2.7 x 10(6) bp was calculated from 21 NotI, 37 SalI, or 27(More)