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Molecular and Cellular Biology, November 1999, p. 7511-7518, Vol. 19, No. 11
Department of Molecular Genetics,
Received 26 July 1999/Accepted 16 August 1999
Both the gene and the cDNA encoding the Rpb4 subunit of RNA
polymerase II were cloned from the fission yeast
Schizosaccharomyces pombe. The cDNA sequence indicates that
Rpb4 consists of 135 amino acid residues with a molecular weight of
15,362. As in the case of the corresponding subunits from higher
eukaryotes such as humans and the plant Arabidopsis
thaliana, Rpb4 is smaller than RPB4 from the budding yeast
Saccharomyces cerevisiae and lacks several segments, which
are present in the S. cerevisiae RPB4 subunit, including
the highly charged sequence in the central portion. The RPB4 subunit of
S. cerevisiae is not essential for normal cell growth but
is required for cell viability under stress conditions. In contrast,
S. pombe Rpb4 was found to be essential even under normal
growth conditions. The fraction of RNA polymerase II containing RPB4 in
exponentially growing cells of S. cerevisiae is about 20%,
but S. pombe RNA polymerase II contains the stoichiometric amount of Rpb4 even at the exponential growth phase. In contrast to the
RPB4 homologues from higher eukaryotes, however, S. pombe Rpb4 formed stable hybrid heterodimers with S. cerevisiae
RPB7, suggesting that S. pombe Rpb4 is similar, in its
structure and essential role in cell viability, to the corresponding
subunits from higher eukaryotes. However, S. pombe Rpb4 is
closer in certain molecular functions to S. cerevisiae RPB4
than the eukaryotic RPB4 homologues.
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
The Rpb4 Subunit of Fission Yeast
Schizosaccharomyces pombe RNA Polymerase II Is Essential for
Cell Viability and Similar in Structure to the Corresponding Subunits
of Higher Eukaryotes
*
Corresponding author. Mailing address: Department of
Molecular Genetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan. Phone: 81-559-81-6741. Fax: 81-559-81-6746. E-mail: aishiham{at}lab.nig.ac.jp.
Molecular and Cellular Biology, November 1999, p. 7511-7518, Vol. 19, No. 11
0270-7306/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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