One interesting aspect of Pif1p is that it is special type of enzyme, a helicase, that unwinds the double strands of DNA. Zakian's research team created a small mutation in the gene that encodes Pif1p so that the protein is produced normally yet lacks this unwinding ability. When telomerase-rich cells carried this mutated gene, Pif1p no longer worked and telomere lengthening progressed unchecked. Zakian believes that Pif1p may work by unzipping a temporary bond that forms between telomerase and the chromosome as telomeres are synthesized.

The experiments were done in baker's yeast cells, but Zakian said that telomere regulation has been so important throughout evolution that human cells employ many of the same mechanisms.

"These are very lowly organisms. This is what we use to bake bread," she said. "However, as we show in this paper, humans have a protein very similar to yeast Pif1p. It would be quite gratifying if it turned out that it also functions in a similar way in humans and could give us insights into human cancer."

'"/>

Contact: Steven Schultz
sschultz@princeton.edu
609-258-5729
Princeton University
3-Aug-2000