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J Keener

Publications and source records attributed to J Keener.

22 records · Page 2Linked to original sources
PubMed1988

In vitro transcription from the late promoter of bacteriophage P4.

The late genes of satellite bacteriophage P4 are cotranscribed from a single promoter which shares little homology with known classes of Escherichia coli promoters (E. Dale, G. Christie, and R. Calendar, J. Mol. Biol. 192:793-803, 1986). In a coupled transcription-translation system, the P4 late gene promoter was activated by either the delta protein of P4 or the ogr protein of helper phage P2 in the absence of any other phage-encoded factor. delta-dependent transcription was inhibited by antibodies to the sigma 70 subunit of E. coli RNA polymerase but was restored by purified sigma 70, indicating that activation of transcription by the delta protein of P4 is dependent on the sigma 70 holoenzyme.

Bacterial Proteins↗
PubMed1987

In vitro transcription of the nitrogen fixation regulatory operon nifLA of Klebsiella pneumoniae.

In vitro transcription from the promoter for the nitrogen fixation regulatory operon nifLA of K. pneumoniae requires four protein fractions: the core form of RNA polymerase; NTRA, an alternate sigma factor; NTRC, an auxiliary DNA-binding protein; and NTRB, a bifunctional enzyme that controls the activity of NTRC by covalent modification (A.J. Ninfa and B. Magasanik, Proc. Natl. Acad. Sci. USA 83:5909, 1986). Two DNA-binding sites for NTRC lie approximately 150 base pairs upstream of the nifLA promoter.

Bacterial Proteins↗
PubMed1985

Products of nitrogen regulatory genes ntrA and ntrC of enteric bacteria activate glnA transcription in vitro: evidence that the ntrA product is a sigma factor.

In enteric bacteria the products of two nitrogen regulatory genes, ntrA and ntrC, activate transcription of glnA, the structural gene encoding glutamine synthetase, both in vivo and in vitro. The ntrC product (gpntrC) is a DNA-binding protein, which binds to five sites in the glnA promoter-regulatory region and appears to activate transcription initiation. Using as an assay the stimulation of glnA transcription in a coupled in vitro transcription-translation system, we have partially purified the ntrA gene product (gpntrA). The following evidence is consistent with the view that gpntrA is a sigma subunit for RNA polymerase: (i) The gpntrA activity copurifies with the sigma 70 holoenzyme (E sigma 70) and core (E) forms of RNA polymerase through several steps but can be separated from them by chromatography on heparin agarose. (ii) After further purification by molecular sieve chromatography, the partially purified gpntrA fraction allows transcription of glnA from the same startpoint used in vivo; transcription is dependent on gpntrC and on added E. The gpntrA fraction does not allow transcription from promoters that we have used as controls, including lacUV5. E sigma 70 has the reverse specificity.

Bacterial Proteins↗