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Viewing report
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DNA Relaxases, the Key Enzymes of Bacterial Conjugation. Edition No. 1
VDM Publishing House, Sep 2008, Pages: 104
Since Sir Alexander Flemming in the early 20th
century discovered penicillin, the war between
bacteria and humans began. The antibiotic saved the
lives of millions of people during the World War II,
but bacteria evolved a mechanism to inactivate the
antibiotics. New antibiotic substances have been
discovered or synthesized but bacteria always seem to
find a way to survive.
The most frequent way how bacteria acquire antibiotic
resistance genes is conjugation. It is a specific,
unidirectional process of horizontal gene transfer,
during which plasmid DNA is transferred from donor to
recipient cell. Relaxases are essential for
conjugative plasmid transfer; they start the process
by nicking plasmid DNA by trans-esterification.
TraA is the DNA relaxase encoded by the
broad-host-range Gram-positive plasmid pIP501.
Small-angle X-ray scattering and chemical
cross-linking proved that TraAN246 and TraA form
dimers in solution. Both proteins revealed oriTpIP501
cleavage activity on supercoiled plasmid DNA in vitro.
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