Polarity of the cysJIH operon of Salmonella typhimurium

Certain point and deletion mutants with lesions in the cysJ gene of Salmonella typhimurium have low levels of enzymes coded by the cysI and cysH genes. These results support the hypothesis that an operon exists comprising genes cysJ, I and H which is transcribed in the direction from cysJ to H. The nearby cysC and cysD genes do not form part of this cysJIH operon.