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Structure and associated DNA-helicase activity of a general transcription initiation factor that binds to RNA
M Sopta1, Z F Burton, J Greenblatt
1Department of Medical Genetics, University of Toronto, Ontario, Canada.
Abstract:
RAP30/74 is a heteromeric general transcription initiation factor which binds to RNA polymerase II. Here we report that preparations of RAP30/74 contain an ATP-dependent DNA helicase whose probable function is to melt the DNA at transcriptional start sites. The sequence of the RAP30 subunit of RAP30/74 indicates that RAP30 may be distantly related to bacterial sigma factors.
Insights
General transcription initiation factor RAP30/74 contains an ATP-dependent DNA helicase. This enzyme likely melts DNA at transcriptional start sites, aiding RNA polymerase II binding.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- RAP30/74 is a heteromeric general transcription initiation factor.
- It plays a crucial role in binding to RNA polymerase II.
Purpose of the Study:
- To investigate the enzymatic activities present in RAP30/74 preparations.
- To identify the function of the newly discovered helicase activity.
Main Methods:
- Biochemical assays to detect DNA helicase activity.
- Protein sequencing of the RAP30 subunit.
Main Results:
- Preparations of RAP30/74 were found to contain an ATP-dependent DNA helicase.
- The RAP30 subunit sequence suggests a distant relationship to bacterial sigma factors.
Conclusions:
- RAP30/74 possesses DNA helicase activity, likely involved in DNA melting at transcriptional start sites.
- The structural similarity of RAP30 to sigma factors may imply conserved roles in transcription initiation.