FIG. 4.

5′ RACE was performed to determine transcripts beginning upstream of nifB1, nifH1, and an internal region of nifU1 (A) and vnfH and ava4055 transcripts (B). Arrows indicate the products that were sequenced. The region amplified is shown as a black line over the gene next to the corresponding RT lanes. (C) The transcription start sites in nifU1 and upstream of nifB1 and ava4055. The distance from the transcription start sites to the start codons of nifH1, nifB1, and ava4055 are shown for each strain. Putative −10 regions (underlined) were selected based only on their location for nifU1 and ava4055 because a consensus −10 site is not present upstream of these transcription start sites. The putative −10 region for nifB was selected due to its similarity to a consensus −10. A direct repeat located approximately −35 to the internal nifU transcriptional start site is also underlined. Transcriptional start sites are shown in boldface and underlined.