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Within-patient HIV evolution reflects the strong selection pressure driving viral escape from cytotoxic T-lymphocyte (CTL) recognition. Whether this intrapatient accumulation of escape mutations translates into HIV evolution at the population level has not been evaluated. We studied over 300 patients drawn from the B- and C-clade epidemics, focusing on(More)
Selectively regulating gene expression in bacteria has provided an important tool for studying gene function. However, well-regulated gene control systems have been restricted primarily for use in laboratory non-pathogenic strains of bacteria (e.g. Escherichia coli, Bacillus subtilis). The development of analogous systems for use in bacterial pathogens such(More)
Escherichia coli induces the expression of more than 50 proteins in response to starvation for a carbon source. Strains MC7 (csi7::phoA) and MC19 (csi19::phoA) contain fusions of a signal peptide-deficient phoA reporter sequence to a csi (carbon starvation-inducible) gene. PhoA expression increased when these strains were deprived of a carbon source or(More)
Starvation of Escherichia coli for potassium, phosphate, or magnesium ions leads to a reversible increase in the rate of protein degradation and an inhibition of ribonucleic acid (RNA) synthesis. In cells deprived of potassium, the breakdown of the more stable cell proteins increased two- to threefold, whereas the hydrolysis of short-lived proteins, both(More)
Entrance into the stationary phase in Escherichia coli induces a group of stress response genes including slp, which encodes an outer membrane lipoprotein. Glucose limitation is sufficient, but not necessary, for the increase in slp expression. The Slp protein was purified and an antibody-based assay was developed, which enabled identification of Slp as(More)
Membrane fractions from Escherichia coli cells expressing DNA damage-inducible (SOS) functions contain elevated quantities of RecA protein (L. J. Gudas and A. B. Pardee, J. Mol. Biol. 101:459-477, 1976). We used two-dimensional polyacrylamide gel electrophoresis to separate membrane proteins from several strains to determine whether this effect is an(More)
When deprived of a carbon source, Escherichia coli induces the synthesis of a group of carbon starvation proteins. The degradation of proteins labeled during starvation was found to be an energy-dependent process which was inhibited by the addition of KCN and accelerated when cells were resupplied with a carbon source. The degradation of the starvation(More)