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. Author manuscript; available in PMC: 2009 Mar 21.
Published in final edited form as: J Mol Biol. 2008 Jan 26;377(2):551–564. doi: 10.1016/j.jmb.2008.01.042

Figure 6.

Figure 6

Effect of ppGpp on transcription initiation by T. thermophilus RNAP. (A) ppGpp (1 mM) does not inhibit transcription by T. thermophilus RNAP. Multi-round transcription from pRLG6770 was measured in 170 mM NaCl transcription buffer at 65°C on a supercoiled template carrying the T. thermophilus 16S rRNA promoter and vector-derived RNA-I promoter (see Materials and Methods). (B) ppGpp (1 mM) does not reduce the lifetime of a promoter complex containing T. thermophilus RNAP. Representative plots show the fraction of heparin-resistant complexes containing T. thermophilus RNAP and the RNA-I promoter on a supercoiled plasmid as a function of time after heparin addition (55°C in 100 mM KCl transcription buffer; see Materials and Methods). The mean ratio of the observed half-lives with/without ppGpp was 0.84 ± 0.17 (3 experiments).