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Rpa12p, a conserved RNA polymerase I subunit with two functional domains
Author(s) -
Mullem Vincent Van,
Landrieux Emilie,
Vandenhaute Jean,
Thuriaux Pierre
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02824.x
Subject(s) - biology , rna polymerase i , polymerase , rna polymerase ii , rna polymerase , specificity factor , microbiology and biotechnology , protein subunit , rna dependent rna polymerase , rna , genetics , gene , gene expression , promoter
Summary Rpa12p is a subunit of RNA polymerase I formed of two zinc‐binding domains. The N‐terminal zinc region (positions 1–60) is poorly conserved from yeast to man. The C‐terminal domain contains an invariant Q.RSADE..T.F motif shared with the TFIIS elongation factor of RNA polymerase II and its archaeal counterpart. Deletions removing the N‐terminal domain fail to grow at 34 ° C, are sensitive to nucleotide‐depleting drugs and become lethal in rpa14‐ Δ mutants lacking the non‐essential RNA polymerase I subunit Rpa14p. They also strongly alter the immunofluorescent properties of RNA polymerase I in the nucleolus. Finally, they prevent the binding of Rpa12p to immunopurified polymerase I and impair a specific two‐hybrid interaction with the second largest subunit. In all these respects, N‐terminal deletions behave like full deletions. In contrast, C‐terminal deletions retaining only the first N‐terminal 60 amino acids are indistinguishable from wild type. Thus, the N‐terminal zinc domain of Rpa12p determines its anchoring to RNA polymerase I and is the only critical part of that subunit in vivo .