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Science. 1996 Jul 5;273(5271):107-9.

Mapping of catalytic residues in the RNA polymerase active center.

Author information

1
Limnological Institute, Russian Academy of Sciences, Irkutsk, Russia.

Abstract

When the Mg2+ ion in the catalytic center of Escherichia coli RNA polymerase (RNAP) is replaced with Fe2+, hydroxyl radicals are generated. In the promoter complex, such radicals cleave template DNA near the transcription start site, whereas the beta' subunit is cleaved at a conserved motif NADFDGD (Asn-Ala-Asp-Phe-Asp-Gly-Asp). Substitution of the three aspartate residues with alanine creates a dominant lethal mutation. The mutant RNAP is catalytically inactive but can bind promoters and form an open complex. The mutant fails to support Fe2+-induced cleavage of DNA or protein. Thus, the NAD-FDGD motif is involved in chelation of the active center Mg2+.

PMID:
8658176
DOI:
10.1126/science.273.5271.107
[Indexed for MEDLINE]

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