Clustering of genes involved in nitrate assimilation in the cyanobacterium Synechococcus.

A region of the genome of the cyanobacterium Synechococcus R2, that bears a cluster of genes involved in nitrate assimilation, has been cloned and the relative positions of some of the genes in the region have been determined. Mutations generated by insertion of an antibiotic-resistance gene cassette into the gene encoding nitrite reductase are associated with reduced expression of nitrate reductase; cotranscription of nitrate assimilation genes in the cluster is inferred from this finding.