ABSTRACT
Myxococcus xanthus, a gram-negative soil bacterium, responds to amino acid starvation by entering a process of multicellular development which culminates in the assembly of spore-filled fruiting bodies. Previous studies utilizing developmental inhibitors (such as methionine, lysine, or threonine) have revealed important clues about the mechanisms involved in fruiting body formation. We used Biolog phenotype microarrays to screen 384 chemicals for complete inhibition of fruiting body development in M. xanthus. Here, we report the identification of a novel inhibitor of fruiting body formation and sporulation, β-d-allose. β-d-Allose, a rare sugar, is a member of the aldohexose family and a C3 epimer of glucose. Our studies show that β-d-allose does not affect cell growth, viability, agglutination, or motility. However, β-galactosidase reporters demonstrate that genes activated between 4 and 14 h of development show significantly lower expression levels in the presence of β-d-allose. Furthermore, inhibition of fruiting body formation occurs only when β-d-allose is added to submerged cultures before 12 h of development. In competition studies, high concentrations of galactose and xylose antagonize the nonfruiting response to β-d-allose, while glucose is capable of partial antagonism. Finally, a magellan-4 transposon mutagenesis screen identified glcK, a putative glucokinase gene, required for β-d-allose-mediated inhibition of fruiting body formation. Subsequent glucokinase activity assays of the glcK mutant further supported the role of this protein in glucose phosphorylation.
FibA and PilA act cooperatively during fruiting body formation of Myxococcus xanthus
