The NTHI SulA ortholog is encoded in a dicistronic operon.

Schematic representation of the genetic context of the classical sulA (from E. coli) and the sulA-related ortholog in NTHI (A). See text for details. In contrast to the monocistronic message produced for the classical sulA, the SulA-related ortholog is produced from a dicistronic operon. RT-PCR was used to validate co-transcription of argR and sulA (B).