PROPERTIES OF A MUTANT FORM OF THE PROKARYOTIC ENHANCER-BINDING PROTEIN, NTRC, WHICH HYDROLYZES ATP IN THE ABSENCE OF EFFECTORS

The mutation S170A in the proposed nucleotide binding site of the tran scriptional activator protein NTRC abolishes its ability to catalyse o pen promoter complex formation by the sigma(N)-RNA polymerase holoenzy me, NTRCS170A has significant ATPase activity, which, in contrast to t he wad-type protein, is unaffected by phosphorylation or binding to en hancer sites on DNA, The mutant protein appears to oligomerise normall y on DNA in response to phosphorylation hut the ATPase activity is app arently nat responsive to changes in oligomerisation state, The defect in transcriptional activation is discussed in relation to mutations i n other sigma(N)-dependent activators. (C) 1998 Federation of European Biochemical Societies.