Identification and Characterization of an FTSQ-Null Suppressor Gene in Streptomyces

Streptomyces coelicolor is a filamentous Gram-positive soil bacterium that grows similarly to fungi. The bacteria grow together in a mycelium-like structure that produces aerial hyphae above the media surface for sporulation. Evenly spaced crosswalls develop during cell division of the aerial filaments with the aid of division genes, including ftsZ and ftsQ. These cell division genes are essential for growth in the common bacterium and if silenced will cause the bacterium to die. Streptomyces uniquely retains the ability for growth after a deletion of either the ftsZ or ftsQ gene which causes a loss of septum formation in the aerial hyphae. Streptomyces proves versatile in that it can survive without any form of division. Discovery and characterization of three new ftsQ-null suppressor strains is the main objective of this study and discovered though visual phenotyping and bioinformatics. An ftsQ-null suppressor mutation was identified through absence of the bellwether overproduction of the antibiotic actinorhodin which normally causes a “blue halo” to form around colonies of the ftsQ-null mutant. This suppressor is able to restore partial septation to the ftsQ-null strain. Subsequently two additional spontaneous suppressors of the ftsQ-null allele were identified with an indistinguishable phenotype from that of the original isolate. Illumina whole genome sequencing was used to find new cell division genes containing single nucleotide polymorphisms in these strains. I discovered that all three strains had a mutation within the same gene referred to as sqnA (suppressor of ftsQ-null). Bioinformatic databases were used to characterize this gene and determine that it is a histidine kinase responsible for signal transduction