A global analysis of developmentally regulated genes in Myxococcus xanthus

Abstract

Tn 5 lac is a transposon that fuses the transcription of lacZ to exogenous promoters. We generated 2374 Tn 5 lac insertion-containing strains of Myxococcus xanthus, a soil bacterium that undergoes multicellular development which culminates in the formation of spores. Thirty-six strains were identified that specifically increase β-galactosidase expression at some particular time during development and these expression times range from minutes after starvation initiates development to 24 hr, when sporulation begins. Different maximum levels of β-galactosidase expression were also observed and the maximum for many strains that begin β-galactosidase expression late in development was observed only if spores were disrupted. Seven of the 36 strains display mild to severe defects in aggregation and/or sporulation, as did an additional five strains whose β-galactosidase expression was not devlopmentally regulated. Restriction maps of the DNA adjacent to the Tn 5 lac insertions that are developmentally regulated and/or cause developmental defects show that most of the 41 insertions are in different regions of the Myxococcus genome. The developmentally regulated Tn 5 lac insertions described here provide a set of at least 29 new developmental markers for Myxococcus.