REHOVOT, Israel ¿ Biocrystallization of genetic material in bacteria with a stress-induced protein confer on bacteria an ¿unprecedented binding and protection mode against stress¿ that also may contribute to bacterial resistance to antibiotics.
That was a conclusion from a team of Weizmann Institute scientists, led by Avi Minsky, professor of organic chemistry. It found that DNA-cocrystallizes with the stress protein Dps, self-assembling almost instantaneously into an extremely stable structure within which ¿the DNA is sequestered and effectively protected against varied assaults such as oxidating agents and starvation, as the team reported in the July 1 issue of Nature. Roberto Kolter, professor of microbiology and molecular genetics at Harvard Medical School, collaborated with Weizmann scientists. His group initially characterized the Dps protein.
¿The tight DNA packing appears to promote the ability of the bacteria to withstand extreme conditions. Hence, prevention of this process may lead to more efficient methods against antibiotic-resistant bacteria,¿ said Minsky, who is exploring common mechanisms that allow bacteria to survive under stress, and that render bacteria resistant to chemical attack during chemotherapy.
¿The rapid molecular transition detected by X-ray analysis and electron microscopy, reflects the bacterial need to survive and grow in very rapidly changing nutrient media, periods of feast alternating with famine and stress,¿ Minsky said. Dps homologs are present in many distantly related bacteria, implying that DNA protection by biocrystallization ¿may be crucial and widespread in prokaryotes, and very specific,¿ he said.
In contrast, complexes between DNA and nonspecific DNA-binding proteins result only in protein-coating DNA molecules or amorphous aggregates.
Minsky compared the protective DNA-protein crystalline assemblies with that found for tightly packed DNA structures in sperm cells, which also must traverse unknown and possibly adverse environments. Weizmann¿s group now is studying the sperm cells for fertility implications.