Chemists trying to produce new and more effective antibiotics have made a surprising discovery; a protein that attaches itself to RNA, making it possible for a certain antibiotic to fight bacterial infection, is remarkably similar to a class of proteins that bind to DNA.
The proteins have the same general shape, and they use a similar method to bind to RNA and DNA. Those similarities came as a surprise because the proteins have completely different functions, and they attach to different structures -- the double-stranded, ladder-like DNA, and the single-stranded RNA.
"You don't expect RNA-binding proteins to look like DNA-binding proteins because the structures in DNA and RNA are quite different," said David Draper, a Johns Hopkins University chemist who is heading the research team that made the discovery.
Draper's team discovered that the RNA- and DNA-binding proteins have the same shape, a configuration of three coils called alpha helices. Not only do they have the same shape, the proteins attach to RNA and DNA at precisely the same points along one of their coils.
A scientific paper detailing the findings was published in the January issue of a British science journal, Nature Structural Biology.
The discovery suggests that the RNA-binding protein, called L11, could be an ancient, ancestral form of other proteins that bind to DNA and are crucial to an embryo's development, turning on and off various genes needed to form specific anatomical features.
L11 has existed for at least 2 billion years, since the time when higher organisms began to diverge from bacteria. By comparison, the similar DNA- binding proteins, called homeodomain proteins, first emerged only about 400 million years ago, Draper said.
In the cells of living organisms, L11 attaches to ribosomes,
produce proteins. The L11 enables the ribosomes to make proteins
fast. When it attaches to the ribosomes in bacteria, the bacteria
are able to
Contact: Emil Venere
Johns Hopkins University