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A 14.4 KDa acidic subunit of human RNA polymerase II with a putative leucine-zipper
J Acker1, M Wintzerith, M Vigneron
1Laboratoire de Génétique Moléculaire des Eucaryotes (CNRS), Unité 184 de Biologie Moléculaire et de Génétique (INSERM), Institut de Chime Biologique de la Faculté de Médecine, Strasbourg, France.
Abstract:
The cDNA of a small subunit (hRPB14.4) of RNA polymerase II (or B) from HeLa cells has been cloned. A 127 residue peptide sequence (calculated molecular weight of 14,478; isoelectric point of 3.7) was deduced and compared to that of the homologous subunit of Saccharomyces cerevisiae polymerase (ABC23, encoded by the RPB6/RPO26 gene). About 50% of the total residues were found to be conserved between yeast and man, with the C-terminal two-third being the most conserved (72% identity). A putative leucine-zipper comprising four properly spaced leucine residues, but not preceded by a basic domain, was identified near the C-terminal end of both proteins.
Insights
Researchers cloned the human RNA polymerase II subunit hRPB14.4. This subunit shows significant sequence conservation with yeast RNA polymerase, suggesting a conserved function in eukaryotes.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- RNA polymerase II (or B) is a crucial enzyme for gene transcription in eukaryotic cells.
- Small subunits play essential roles in the structure and function of RNA polymerase II.
- Understanding the conservation of these subunits across species can provide insights into fundamental biological processes.
Purpose of the Study:
- To clone and characterize the cDNA of a small subunit of human RNA polymerase II (hRPB14.4).
- To compare the deduced peptide sequence of hRPB14.4 with its homologous subunit in Saccharomyces cerevisiae.
- To identify conserved regions and functional motifs between human and yeast RNA polymerase II subunits.
Main Methods:
- Cloning of the cDNA for the small subunit (hRPB14.4) of RNA polymerase II from HeLa cells.
- Deduction of the 127-residue peptide sequence from the cloned cDNA.
- Sequence comparison analysis between human hRPB14.4 and Saccharomyces cerevisiae ABC23 subunit.
Main Results:
- The cDNA of the human RNA polymerase II small subunit (hRPB14.4) was successfully cloned.
- A 127-residue peptide sequence was deduced, with a molecular weight of 14,478 and an isoelectric point of 3.7.
- Approximately 50% residue conservation was observed between human hRPB14.4 and yeast ABC23, with 72% identity in the C-terminal two-thirds.
- A potential leucine-zipper motif was identified near the C-terminal end of both human and yeast proteins.
Conclusions:
- The human RNA polymerase II small subunit hRPB14.4 shares significant sequence homology with its yeast counterpart.
- The high conservation suggests a conserved functional role for this subunit in eukaryotic transcription.
- The identified leucine-zipper motif may indicate a role in protein-protein interactions or complex assembly.