Characterization of the mac-1 gene encoding a putative ABC transporter from Myxococcus xanthus

The mac-1 gene of Myxococcus xanthus TA, an antibiotic TA producer, encoded a protein with strong sequence similarity to the antibiotic ATP-binding ca ssette (ABC) transporter for macrolide antibiotics. The mac-1 gene encoding protein (Mac-1) had two ATP-binding domains containing Walker A and B moti fs, and no hydrophobic transmembrane regions. Insertional inactivation of m ac-1 caused enhanced sensitivity to oleandomycin, a macrolide antibiotic, w hile the mac-1 mutant showed normal export of antibiotic TA into the extrac ellular fluid. The mac-1 mutant could form mounds, but was unable to form f ruiting bodies or sporulate under nutrient starvation. A primary role for M ac-1 in M. xanthus may be as a transporter which exports or imports a molec ule required for the sporulation process.