Toxoflavin received its name because its chemical and
physical properties are similar to those of riboflavin, a
water-soluble vitamin. Riboflavin, essential for basic
metabolism, has important coenzyme forms: riboflavin
5-phosphate (FMN) and flavin adenine dinucleotide.
Knowledge about the pathway and genes for riboflavin biosynthesis
can provide useful information for understanding
the mechanism of toxoflavin biosynthesis by B. glumae. It is
known that, starting from guanosine 5-triphosphate (GTP)
and ribose-5-phosphate, six enzymatic reactions are specific
for the biosynthetic pathway of riboflavin (Bacher 1991).
The riboflavin synthesis genes of Bacillus subtilis, the most
extensively studied system, are located and co-regulated in
an operon structure that consists of five genes (Mironov et
al. 1989; Sorokin et al. 1993).