A GLGC GENE ESSENTIAL ONLY FOR THE FIRST OF 2 SPATIALLY DISTINCT PHASES OF GLYCOGEN-SYNTHESIS IN STREPTOMYCES-COELICOLOR A3(2)

By using a PCR approach based on conserved regions of ADP-glucose pyro phosphorylases, a glgC gene was cloned from Streptomyces coelicolor A3 (2). The deduced glgC gene product showed end-to-end relatedness to ot her bacterial ADP-glucose pyrophosphorylases. The glgC gene is about 1 ,000 kb from the leftmost chromosome end and is not Closely linked to either of the two glgB genes of S. coelicolor, which encode glycogen b ranching enzymes active in different locations in differentiated colon ies. Disruption of glgC eliminated only the first of two temporal peak s of GDP-glucose pyrophosphorylase activity and glycogen accumulation and prevented cytologically observable glycogen accumulation in the su bstrate mycelium of colonies (phase I), while glycogen deposition in y oung spore chains (phase II) remained readily detectable. The cloned g lgC gene therefore encodes an ADP-glucose pyrophosphorylase essential only for phase I (and it is therefore named glgCI). A second, phase II -Specific, glgC gene should also exist in S. coelicolor, though it was not detected by hybridization analysis.