CLONING AND NUCLEOTIDE SEQUENCING OF A 15 KB REGION OF THE BACILLUS-SUBTILIS GENOME CONTAINING THE IOL OPERON

Within the framework of an international project on the sequencing of the whole Bacillus subtilis genome, a 15 kb chromosome segment, which contains the iol operon involved in inositol utilization, has been cloned and sequenced. This region (14974 bp) contains 12 complete open reading frames (ORFs; genes) and two partial ones; the seventh gene (E83G) is the idh gene encoding inositol dehydrogenase. All the genes identified are transcribed in the same direction as that of the movement of the replication fork. A homology search for their products deduced from the 12 complete ORFs revealed that eight of them exhibit significant homology to known proteins such as fructokinase, acetolactate synthase, fructose-1,6-bisphosphate aldolase (B. subtilis). and PhoB and FtsE proteins (Escherichia coli). It also implied that two genes (B65D and B65E) might encode a set of two-component regulatory proteins and that the BGSF gene might encode a protein belonging to the ATP-binding cassette (ABC) family. Based on the features of the nucleotide sequence determined and the results of the homology search, the primary structure of the iol operon is predicted.