Two new loci affecting cell division identified as suppressors of an ftsQ-null mutation in Streptomyces coelicolor A3(2)

Mutations in fts genes partially or completely block both vegetative cell d ivision and sporulation septation in the filamentous bacterium Streptomyces coelicolor A3(2). Using a novel screen, we independently isolated two doub le-mutant strains, each containing a spontaneous suppressor mutation, which partially restores division to an ftsQ-null mutant. Genetic complementatio n experiments revealed that the suppressor mutations alone confer no observ able defect in sporulation. The suppressor mutations were genetically mappe d to regions of the chromosome, distinct from each other and the division a nd cell wall cluster containing ftsQ. Therefore, the genes identified by th e suppressor mutations were named sqnA and sqnB (suppressor of ftsQ-null) a nd may be representatives of a novel class of genes involved in cell divisi on or the regulation of cell division in this mycelial organism. (C) 2001 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.