Characterization of RomX and RomY, two novel motility regulators in Myxococcus xanthus

The rod-shaped Myxococcus xanthus cells move with defined leading and lagging cell poles on surfaces. Occasionally, cells undergo reversals, which correspond to an inversion of the leading-lagging polarity axis. Reversals depend on relocalization between the poles of three polarly localized proteins that regulate polarity, i.e. the Ras-like GTPase MglA, its cognate GAP MglB, and the response regulator RomR. To understand how these three proteins localize dynamically to the cell poles, we performed a phylogenomic analysis and identified two uncharacterized proteins, RomX and RomY, that co-occur with RomR. Here, we report on the function of RomX and RomY in motility.