title: The asgE locus is required for cell-cell signalling during Myxococcus xanthus development.
abstract: In response to starvation, Myxococcus xanthus undergoes a multicellular developmental process that produces a dome-shaped fruiting body structure filled with differentiated cells called myxospores. Two insertion mutants that block the final stages of fruiting body morphogenesis and reduce sporulation efficiency were isolated and characterized. DNA sequence analysis revealed that the chromosomal insertions are located in open reading frames ORF2 and asgE, which are separated by 68 bp. The sporulation defect of cells carrying the asgE insertion can be rescued phenotypically when co-developed with wild-type cells, whereas the sporulation efficiency of cells carrying the ORF2 insertion was not improved when mixed with wild-type cells. Thus, the asgE insertion mutant appears to belong to a class of developmental mutants that are unable to produce cell-cell signals required for M. xanthus development, but they retain the ability to respond to them when they are provided by wild-type cells. Several lines of evidence indicate that asgE cells fail to produce normal levels of A-factor, a cell density signal. A-factor consists of a mixture of heat-stable amino acids and peptides, and at least two heat-labile extracellular proteases. The asgE mutant yielded about 10-fold less heat-labile A-factor and about twofold less heat-stable A-factor than wild-type cells, suggesting that the primary defect of asgE cells is in the production or release of heat-labile A-factor.
authors.affiliation: Section of Microbiology, One Shields Avenue, University of California, Davis, Davis, CA 95616, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: Garza
authors.forename: B Z
authors.initials: BZ
authors.lastname: Harris
authors.forename: J S
authors.initials: JS
authors.lastname: Pollack
authors.forename: M
authors.initials: M
authors.lastname: Singer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D003470:Culture Media / Q000494:pharmacology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005816:Genetic Complementation Test / Q000379:methods; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000187:drug effects / Q000235:genetics; D016254:Mutagenesis, Insertional; D016941:Myxococcus xanthus / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D010641:Phenotype; D010770:Phosphotransferases; D011402:Pronase / Q000494:pharmacology; D012045:Regulatory Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C063576:CsgA protein, Myxococcus xanthus; D003470:Culture Media; D004269:DNA, Bacterial; D010770:Phosphotransferases; C093119:AsgA protein, Myxococcus xanthus; D011402:Pronase