Evolution Is Driven By Gene Regulation

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Evolution Is Driven By Gene Regulation

http://www.medicalnewstoday.com/articles/79324.php

It is not just what's in your genes, it's how you turn them on that

accounts for the difference between species - at least in yeast -

according to a report by Yale researchers in this week's issue of

Science.

" We've known for a while that the protein coding genes of humans and

chimpanzees are about 99 percent the same, " said senior author

Snyder, the Cullman Professor of Molecular Cellular and

Developmental Biology at Yale. " The challenge for biologists is

accounting for what causes the substantial difference between the

person and the chimp. "

Conventional wisdom has been that if the difference is not the gene

content, the difference must be in the way regulation of genes

produces their protein products.

Comparing gene regulation across similar organisms has been

difficult because the nucleotide sequence of DNA regulatory regions,

or promoters, are more variable than the sequences of their

corresponding protein-coding regions, making them harder to identify

by standard computer comparisons.

" While many molecules that bind DNA regulatory regions have been

identified as transcription factors mediating gene regulation, we

have now shown that we can functionally map these interactions and

identify the specific targeted promoters, " said Snyder. " We were

startled to find that even the closely related species of yeast had

extensively differing patterns of regulation. "

In this study, the authors found the DNA binding sites by aiming at

their function, rather than their sequence. First, they isolated

transcription factors that were specifically bound to DNA at their

promoter sites. Then, they analyzed the sequences that were isolated

to determine the similarities and differences in regulatory regions

between the different species.

" By using a group of closely and more distantly related yeast whose

sequences were well documented, we were able to see functional

differences that had been invisible to researchers before, " said

Snyder. " We expect that this approach will get us closer to

understanding the balance between gene content and gene regulation

in the question of human-chimp diversity. "

Other authors on the paper were Mark Gerstein, R. Borneman,

Tara A. Gianoulis, Zhengdong D. Zhang, Haiyuan Yu, Rozowsky and

R. Seringhaus at Yale and Lu Yong Wang at Siemans Corporate

Research, Princeton NJ. The study was funded by grants from the

National Institutes of Health and the Burroughs Wellcome Foundation.

Citation: Science 317: 815-819 (August 10, 2007).

http://www.yale.edu