CHAPEL HILL - The minimum number of protein-producing genes a single-celled organism needs to survive and reproduce in the laboratory is somewhere between 265 and 350, according to new research directed by a top University of North Carolina at Chapel Hill scientist.
Using a technique known as global transposon mutagenesis, Dr. Clyde A. Hutchison III, professor of microbiology at the UNC-CH School of Medicine, and colleagues at The Institute for Genomic Research (TIGR) in Rockville, Md., found that roughly a third of the genes in the disease-causing Mycoplasma genitalium were unnecessary for the bacterium's survival.
The technique -- a process of elimination -- involved randomly inserting bits of unrelated DNA into the middle of genes to disrupt their function and see if the organism thrived anyway.
Such research is a significant step forward in creating minimal, tailor-made life forms that can be further altered for such purposes as making biologically active agents for treating illness, Hutchison said. More immediately, it boosts scientists' basic understanding of the question, "What is life?"
"Cells that grow and divide after this procedure can have such disruptive insertions only in non-essential genes," he said. "Surprisingly, the minimal set of genes we found included about 100 whose function we don't yet understand. This finding calls into question the prevailing assumption that the basic molecular mechanisms underlying cellular life are understood, at least broadly."
Further work will explain those functions and create a more exact number of the minimal genes required to create life in the laboratory, the scientist said. New organisms bearing only the fewest genes needed to survive could have major commercial, social and ethical implications.
A report on the research appears in the Dec. 10 issue of the journal Science. Besides Hutchison, authors are Drs. Scott Peterson (Hutchison's former student), Steve Gill, Robin Cline, Owen
Contact: David Williamson
University of North Carolina at Chapel Hill