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Updated: Jul 13, 2026
14:09
Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System
Published on: March 18, 2010
RNA polymerase I transcription factor Rrn3 is functionally conserved between yeast and human
B Moorefield1, E A Greene, R H Reeder
1Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA.
Summary
Researchers cloned a human RNA polymerase I transcription factor, Rrn3, functionally conserved in yeast and mammals. This discovery suggests a shared mechanism for regulating ribosomal RNA synthesis across eukaryotes.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- RNA polymerase I (Pol I) is crucial for synthesizing ribosomal RNA (rRNA).
- Transcription factors regulate Pol I activity, but their conservation across species is not fully understood.
- Rrn3 is a known Pol I transcription factor in yeast.
Purpose of the Study:
- To identify and characterize a human homolog of the yeast Rrn3 transcription factor.
- To investigate the functional conservation of Rrn3 between yeast and mammals.
- To explore the implications for rRNA synthesis regulation.
Main Methods:
- Cloning of a human cDNA encoding a putative Rrn3 homolog.
- Expression and purification of the recombinant human protein.
- Functional assays in a yeast strain with a disrupted RRN3 gene (in vivo rescue).
- Site-directed mutagenesis of conserved amino acids.
Main Results:
- A human cDNA related to yeast Rrn3 was successfully cloned.
- The recombinant human Rrn3 protein showed sequence similarity and immunological cross-reactivity to yeast Rrn3.
- The human Rrn3 functionally rescued the yeast RRN3 disruption mutant.
- A conserved point mutation abolished the function of both yeast and human Rrn3, confirming functional significance.
Conclusions:
- Human Rrn3 is functionally conserved with yeast Rrn3.
- This marks the first RNA polymerase I-specific transcription factor found to be conserved between yeast and mammals.
- Suggests conserved mechanisms for regulating ribosomal RNA synthesis in eukaryotes.
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