Multiple independent evolutionary solutions to core histone gene regulation
Leonardo Mariño-Ramírez1, I King Jordan, David Landsman
1Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, 8600 Rockville Pike, Bethesda, Maryland 20894-6075, USA.
Genome Biology
|December 23, 2006
Summary
Core histone gene expression is conserved across species, but the regulatory mechanisms driving it are highly divergent. This suggests a dynamic evolution of gene regulation, particularly in promoter sequences.
Area of Science:
- Evolutionary biology
- Genetics
- Molecular biology
Background:
- Core histone genes exhibit conserved, periodic expression patterns peaking during S phase across diverse species.
- This conserved expression is fundamental from yeast to humans.
Purpose of the Study:
- To investigate the evolutionary dynamics of regulatory mechanisms controlling conserved histone gene expression.
- To compare the evolutionary trajectories of histone gene regulation versus protein sequence conservation.
Main Methods:
- Comparative analysis of cis-regulatory sequence motifs and transcription factors across species.
- Examination of evolutionary turnover in regulatory machinery.
- Sequence and structure comparisons of histone families (H2A, H2B, H3, H4).
Main Results:
- Histone gene regulatory machinery shows significant divergence between species, contrasting with conserved expression patterns.
- Substantial evolutionary turnover of cis-regulatory motifs and transcription factors was observed.
- Regulatory mechanisms are more conserved within species than within gene families.
- Histone protein sequences are more conserved within families than between them, reflecting common ancestry.
- H2A/H2B and H3/H4 form distinct evolutionary groups, aligning with nucleosome assembly dynamics.
Conclusions:
- A significant "dissonance" exists between conserved histone gene regulatory phenotypes and divergent regulatory mechanisms.
- This points to a highly dynamic mode of regulatory evolution for core histone genes.
- The extensive "solution space" for functionally viable promoter cis-regulatory sites likely facilitates this dynamic regulatory evolution.
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