Analysis of functional properties of PirA and ScdA in Myxococcus xanthus

The twin-arginine translocation (Tat) system contributes to export of various important proteins for development and growth for Myxococcus xanthus. In this study, two genes encoding putative Tat protein substrates (a Pirin (PirA) and a short chain dehydrogenase (ScdA)) were disrupted by insertion of the kanamycine resistance gene, and the biological function of these proteins were determined. Both mutants showed normal growth in non-osmotic and osmotic condition. When allowed to develop on starvation medium, pirA and scd4 mutants formed normal fruiting bodies, however, the spores of scdA mutant were slightly decreased. Under non-osmotic or osmotic-stress, the pirA mutant spores germinated at the same rate as wild-type spores.