Rpc25, a conserved RNA polymerase III subunit, is critical for transcription initiation

• Published in: Molecular microbiology 2005-01, Vol.55 (1), p.104-114
• Main Authors: Zaros, Cécile, Thuriaux, Pierre
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Archaea; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Fungal; Genetic Complementation Test; Microbiology; Models, Molecular; Molecular Sequence Data; Mutation; Protein Subunits - genetics; Protein Subunits - physiology; RNA Polymerase III - genetics; RNA Polymerase III - isolation & purification; RNA Polymerase III - physiology; RNA Precursors - metabolism; RNA, Fungal - metabolism; Schizosaccharomyces - enzymology; Schizosaccharomyces - genetics; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - physiology; Sequence Homology, Amino Acid; Transcription, Genetic
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2004.04375.x

Summary Rpc25 is a strongly conserved subunit of RNA polymerase III with homology to Rpa43 in RNA polymerase I, Rpb7 in RNA polymerase II and the archaeal RpoE subunit. A central domain of Rpc25 can replaced the corresponding region of Rpb7 with little or no growth defect, underscoring the functional relatedness of these proteins. Rpc25 forms a heterodimer with Rpc17, another conserved component of RNA polymerase III. A conditional mutant (rpc25‐S100P) impairs this interaction. rpc25‐S100P and another conditional mutant obtained by complementation with the Schizosaccharomyces pombe subunit (rpc25‐Sp) were investigated for the properties of their purified RNA polymerase III. The mutant enzymes were defective in the specific synthesis of pre‐tRNA transcripts but acted at a wild‐type level on poly[d(A‐T)] templates. They were also indistinguishable from wild type in transcript elongation, cleavage and termination. These data indicate that Rpc25 is needed for transcription initiation but is not critical for the elongating properties of RNA polymerase III.