Previous Article | Next Article ![]()
J. Bacteriol., 10 1996, 5668-5675, Vol 178, No. 19
B Julien and R Calendar
Transcription from the late promoters of bacteriophage P2 and its satellite
phage P4 is activated by a unique class of small, zinc- binding proteins.
Using plasmid expression systems, we compared activators from two P2-like
(helper) phages with those encoded by two satellite phages. The helper
phage activators have more activity on the P4 phage sid promoter. In
contrast, the satellite phage activators function better on the four late
P2 promoters and on the P4 late leftward promoter. We purified one
activator encoded by a P2-like phage and an activator from a satellite
phage and determined their binding sites within the P2 and P4 late
promoters. Differences in activity levels correlate with binding
specificities; promoters that function best with the satellite phage
activators have only one activator binding site centered at -55, while the
P4 sid promoter, which has more activity with helper phage activators, has
a second binding site centered at -18. Surprisingly, DNase I footprinting
revealed only very minor differences in promoter binding by the two
activators reported here and the P4 activator reported previously. Thus,
the differences in transcriptional activity are probably due to
interactions between the activators and RNA polymerase, rather than
interactions between the activators and DNA.
Copyright © 1996, American Society for Microbiology
Bacteriophage PSP3 and phiR73 activator proteins: analysis of promoter specificities
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3204, USA.
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»