Low-temperature induction of Myxococcus xanthus developmental gene expression in wild-type and csgA suppressor cells.
The csgA gene encodes an extracellular protein that plays an essential role in the regulation of fruiting-body formation and sporulation of Myxococcus xanthus. The csgA suppressor allele soc-500 (formerly referred to as csp-500) was selected based on its ability to restore sporulation to csgA cells under developmental conditions at 32 degrees C. The soc-500 allele was subsequently found to induce sporulation of csgA+ or csgA cells simply by shifting the temperature of vegetatively growing cells to 15 degrees C. Low-temperature-induced sporulation of soc-500 strains occurred in the absence of two requirements for fruiting-body sporulation: low nutrient levels and a high temperature. Low temperature alone caused the expression of many developmentally regulated genes but did not support the development of wild-type cells. The soc-500 allele appears to activate genes involved with sensing nutritional stress. At low temperature on a nutritionally rich medium, soc-500 induced expression of the tps gene which is normally expressed following nutritional shiftdown. The soc-500 allele was cloned and integrated into the wild-type chromosome by site-specific recombination. It was dominant over the wild-type allele in merodiploids and is contained on a 3-kbp DraI-ClaI restriction fragment. The soc-500 transcriptional unit spans a 300-bp PstI-PstI restriction fragment, since deletion of the PstI restriction fragment inhibits both csgA suppression and low-temperature induction. These results suggest that the soc-500 mutation lies in a gene that is involved in nutrient sensing.
Rhie
H G
HG
Department of Microbiology, University of Georgia, Athens 30602.
Shimkets
L J
LJ
D000483:Alleles; D002454:Cell Differentiation; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D015964:Gene Expression Regulation, Bacterial; D016153:Genes, Suppressor; D009231:Myxococcales / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D015183:Restriction Mapping; D013171:Spores, Bacterial
D011993:Recombinant Fusion Proteins