Open AccessRole of Second-Largest RNA Polymerase I Subunit Zn-Binding Domain in Enzyme Assembly
Author(s) -
Tatyaryshkina,
Adrian Bruning,
Olivier Gadal,
Konstantin Severinov
Publication year - 2003
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.2.5.1046-1052.2003
Subject(s) - biology , polymerase , protein subunit , rna polymerase , rna polymerase i , biochemistry , rna , specificity factor , microbiology and biotechnology , rna polymerase ii , binding domain , binding site , rna dependent rna polymerase , enzyme , genetics , gene , gene expression , promoter
The second-largest subunits of eukaryal RNA polymerases are similar to the beta subunits of prokaryal RNA polymerases throughout much of their lengths. The second-largest subunits from eukaryal RNA polymerases contain a four-cysteine Zn-binding domain at their C termini. The domain is also present in archaeal homologs but is absent from prokaryal homologs. Here, we investigated the role of the C-terminal Zn-binding domain of Rpa135, the second-largest subunit of yeast RNA polymerase I. Analysis of nonfunctional Rpa135 mutants indicated that the Zn-binding domain is required for recruitment of the largest subunit, Rpa190, into the RNA polymerase I complex. Curiously, the essential function of the Rpa135 Zn-binding domain is not related to Zn(2+) binding per se, since replacement of only one of the four cysteine residues with alanine led to the loss of Rpa135 function. Even more strikingly, replacement of all four cysteines with alanines resulted in functional Rpa135.