Contains a 1.9kb HindIII-NaeI fragment which encodes ems sequence from 1.5kb upstream of the transcription start site to base pair 117 of the coding region fused in frame to lacZ. Also contains a 1.6kb ems fragment containing an element necessary for early ems expression (-8.2kb to -6.6kb relative to the transcription start site) upstream of the 1.9kb ems fragment.