Previous Article | Next Article ![]()
Molecular and Cellular Biology, May 2003, p. 3329-3338, Vol. 23, No. 9
0270-7306/03/$08.00+0 DOI: 10.1128/MCB.23.9.3329-3338.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Department of Molecular Genetics, Microbiology and Immunology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854-5635
Received 12 September 2002/ Returned for modification 16 October 2002/ Accepted 17 January 2003
We have identified a conditional mutation in the shared Rpb6 subunit, assembled in RNA polymerases I, II, and III, that illuminated a new role that is independent of its assembly function. RNA polymerase II and III activities were significantly reduced in mutant cells before and after the shift to nonpermissive temperature. In contrast, RNA polymerase I was marginally affected. Although the Rpb6 mutant strain contained two mutations (P75S and Q100R), the majority of growth and transcription defects originated from substitution of an amino acid nearly identical in all eukaryotic counterparts as well as bacterial
subunits (Q100R). Purification of mutant RNA polymerase II revealed that two subunits, Rpb4 and Rpb7, are selectively lost in mutant cells. Rpb4 and Rpb7 are present at substoichiometric levels, form a dissociable subcomplex, are required for RNA polymerase II activity at high temperatures, and have been implicated in the regulation of enzyme activity. Interaction experiments support a direct association between the Rpb6 and Rpb4 subunits, indicating that Rpb6 is one point of contact between the Rpb4/Rpb7 subcomplex and RNA polymerase II. The association of Rpb4/Rpb7 with Rpb6 suggests that analogous subunits of each RNA polymerase impart class-specific functions through a conserved core subunit.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»