HOUSTON (May 1, 2007) - A protein called RecQ takes on a totally opposite function in the bacteria Escherichia coli to the one it fulfills in yeast and in humans, indicating that people seeking to understand the role of different forms in human cells and disease need to consider both possibilities, said researchers from Baylor College of Medicine in a report in the current issue of Molecular Cell.
Humans have five forms of this particular protein, and three are associated with syndromes that predispose people to cancer, said Dr. Susan Rosenberg, professor of molecular and human genetics at Baylor College of Medicine. Two of the forms are not associated with cancer syndromes.
Other organisms have forms of this protein in varying numbers, said Rosenberg. For example, E. coli has only one. All forms appear to be very similar, no matter what the organism. When proteins are found in a variety of organisms, they are called conserved.
"It was thought that because these were so well conserved, they should do more or less the same thing," said Rosenberg. However, research in her laboratory showed this was not the case.
In yeast and one of the human forms of a protein called RecQ actually works to help unzip DNA strands when chromosomes repair DNA damage using a process called genetic recombination. In this kind of repair, one chromosome aggregates with a partner chromosomeusually its twin chromosome following DNA replicationand then disaggregates following repair. If the repair aggregates are not unzipped, the chromosomes can't separate for reproduction. The yeast and human Werner syndrome enzymes helps prevent the buildup of unwanted intermediates of aggregated chromosomes that can actually kill the cells if not unzipped.
When that protein is lacking, the intermediates buildup and the cells die. However, while many people think all such proteins work similarly in repair, recent work by Rosenberg and others in her la
Contact: Graciela Gutierrez
Baylor College of Medicine