Characteristics of bypass glnAp2 transcription using wild-type sigma 54. Unless otherwise indicated, reactions were at standard conditions (37°C, supercoiled DNA, 10 mM added KCl; ATP, CTP, and GTP added before heparin and UTP; no activator) yielding the RNA shown in lane 2. Lanes: 1, activated transcription with phosphorylated NtrC and only ATP added prior to heparin; 3, temperature increased to 47°C; 4, sigma 54 omitted; 5, heparin (100 μg/ml) added prior to nucleotides; 6, ATP substituted with nonhydrolyzable β–γ bond analog AMP–PNP; 7, linear template.