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Localization of the yeast RNA polymerase I‐specific subunits
Author(s) -
Bischler Nicolas,
Brino Laurent,
Carles Christophe,
Riva Michel,
Tschochner Herbert,
Mallouh Véronique,
Schultz Patrick
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf392
Subject(s) - rna polymerase i , protein subunit , rna , processivity , rna polymerase , polymerase , microbiology and biotechnology , specificity factor , rna polymerase ii , biology , rna polymerase iii , dna , chemistry , biochemistry , gene , gene expression , promoter
The spatial distribution of four subunits specifically associated to the yeast DNA‐dependent RNA polymerase I (RNA pol I) was studied by electron microscopy. A structural model of the native enzyme was determined by cryo‐electron microscopy from isolated molecules and was compared with the atomic structure of RNA pol II Δ4/7, which lacks the specific polypeptides. The two models were aligned and a difference map revealed four additional protein densities present in RNA pol I, which were characterized by immunolabelling. A protruding protein density named stalk was found to contain the RNA pol I‐specific subunits A43 and A14. The docking with the atomic structure showed that the stalk protruded from the structure at the same site as the C‐terminal domain (CTD) of the largest subunit of RNA pol II. Subunit A49 was placed on top of the clamp whereas subunit A34.5 bound at the entrance of the DNA binding cleft, where it could contact the downstream DNA. The location of the RNA pol I‐specific subunits is correlated with their biological activity.