Figure 4

asl2028 promoter- gfp was expressed in vegetative cells. A. Map of full length and truncated promoter regions upstream of asl2028 that were used to drive GFP reporter expression. Black bar indicates HetR binding site. B. The asl2028 full length promoter fused to gfp in WT cells was expressed in vegetative cells (0 h) and showed a slight increase in expression in vegetative cells at 6, 12, and 21 hours after nitrogen deprivation. The asl2028-gfp reporter was not expressed in heterocysts at 21 hours after nitrogen deprivation. The full-length asl2028 promoter was expressed at a lower level in the ΔhetR mutant background compared to its expression in WT cells.