Miroslav Radman

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Deinococcus radiodurans is a robust bacterium best known for its capacity to repair massive DNA damage efficiently and accurately. It is extremely resistant to many DNA-damaging agents, including ionizing radiation and UV radiation (100 to 295 nm), desiccation, and mitomycin C, which induce oxidative damage not only to DNA but also to all cellular(More)
The evolutionary significance of stress-induced mutagenesis was evaluated by studying mutagenesis in aging colonies (MAC) of Escherichia coli natural isolates. A large fraction of isolates exhibited a strong MAC, and the high MAC variability reflected the diversity of selective pressures in ecological niches. MAC depends on starvation, oxygen, and RpoS and(More)
The requirement for DNA sequence homology in generalized genetic recombination is greatly relaxed in bacterial mutL, mutS and mutH mutants deficient in mismatch repair. In such mutants, intergeneric recombination occurs efficiently between Escherichia coli and Salmonella typhimurium, which are approximately 20% divergent in DNA sequence. This finding has(More)
Because most newly arising mutations are neutral or deleterious, it has been argued that the mutation rate has evolved to be as low as possible, limited only by the cost of error-avoidance and error-correction mechanisms. But up to one per cent of natural bacterial isolates are 'mutator' clones that have high mutation rates. We consider here whether high(More)
Dehydration or desiccation is one of the most frequent and severe challenges to living cells. The bacterium Deinococcus radiodurans is the best known extremophile among the few organisms that can survive extremely high exposures to desiccation and ionizing radiation, which shatter its genome into hundreds of short DNA fragments. Remarkably, these fragments(More)
We have shown that bacterial mutation rates change during the experimental colonization of the mouse gut. A high mutation rate was initially beneficial because it allowed faster adaptation, but this benefit disappeared once adaptation was achieved. Mutator bacteria accumulated mutations that, although neutral in the mouse gut, are often deleterious in(More)
Deinococcus radiodurans is among a small number of bacterial species that are extremely resistant to ionizing radiation, UV light, toxic chemicals, and desiccation. We measured proteome oxidation (i.e., protein carbonylation, PC) in D. radiodurans as well as in standard and evolved resistant strains of Escherichia coli exposed to ionizing radiation or UVC(More)
Speciation involves the establishment of genetic barriers between closely related organisms. The extent of genetic recombination is a key determinant and a measure of genetic isolation. The results reported here reveal that genetic barriers can be established, eliminated, or modified by manipulating two systems which control genetic recombination, SOS and(More)
Conjugation allows bacteria to acquire genes for antibiotic resistance, novel virulence attributes, and alternative metabolic pathways. Using a fluorescent protein fusion, SeqA-YFP, we have visualized this process in real time and in single cells of Escherichia coli. We found that the F pilus mediates DNA transfer at considerable cell-to-cell distances.(More)
In this study, we show a correlation between synthesis of aberrant proteins and their oxidative modification. The level of aberrant proteins was elevated in Escherichia coli cultures by decreasing transcriptional or translational fidelity using specific mutations or drugs. Protein carbonylation, an oxidative modification, increased in parallel to the(More)