The bacterium that stole some human DNA

Sean Lavery and Sean Lavery

Researchers at the Feinberg School of Medicine have discovered a klepto characteristic of a gonorrhea-causing bacterium that allowed it, in an evolutionary event, to steal human DNA, according to a paper published Monday in the online journal mBio.

The results of the research present the first ever discovery of a human DNA fragment in a bacterial genome, according to a University news release.

Hank Seifert, a professor of microbiology and immunology at Feinberg, said the study could influence further understanding about the evolution of bacteria. Seifert, who holds a doctorate in molecular biology, was the study’s senior author.

“This has evolutionary significance because it shows you can take broad evolutionary steps when you’re able to acquire these pieces of DNA,” he said. “The bacterium is getting a genetic sequence from the very host it’s infecting. That could have far-reaching implications as far as how the bacteria can adapt to the host.”

Seifert said he found the ancient accounts of a disease similar to gonorrhea recorded in the Bible and said researchers were focusing on the bacterium’s ability to change its appearance and mimic white blood cells.

Despite its long and storied history, gonorrhea has remained one of the few diseases exclusive to humans. The disease is transferred through sexual contact and can be particularly dangerous to women if left untreated.

Lead author and postdoctoral fellow in microbiology Mark Anderson said the ability for gene transfer between different bacteria has been known.

“Human DNA to a bacterium is a very large jump,” Anderson said in the University news release. “This bacterium had to overcome several obstacles in order to acquire this DNA sequence.”

Anderson sequenced the bacteria genome fragment and determined that it was in fact identical to the human fragment. The researchers also studied a meningitis-causing bacterium that did not contain the human DNA fragment. The results suggest the DNA transfer was a relatively recent evolutionary event.

Seifert said the discovery will lead to further research.

“Whether this particular event has provided an advantage for the gonorrhea bacterium, we don’t know yet,” he said. “The next step is to figure out what this piece of DNA is doing.”

[email protected]