Regulation of FRUA expression during vegetative growth and development of Myxococcus xanthus.
Expression of the fruA gene, encoding a putative transcription factor essential for fruiting body formation of Myxococcus xanthus, is specifically activated during development. In the present study, we have analyzed the mechanism of the transcriptional regulation of fruA expression. From gel retardation and footprinting assays using various fruA regulatory regions as probes and competitors, a protein designated factor X was found to specifically bind to a sequence (xbs) located downstream of the transcription-initiation site (+78 to +94) of the fruA gene. Factor X activity was present during vegetative growth and decreased during early development. Analysis of promoter activities of various segments of the fruA regulatory region using the lacZ reporter gene in vivo indicated that a DNA segment extending 45-bp upstream from the transcription-initiation site was required for developmentally regulated fruA expression at a low level. In addition, cis-acting regulatory regions located upstream and downstream of the fruA promoter region and including C-box and xbs, were found to be involved in regulation of fruA expression during development. When inserted into the vegA gene, the xbs element inhibited vegA expression during vegetative growth. Together with previously reported results, our studies reveal that fruA expression is regulated by both positive and negative mechanisms during the M. xanthus life cycle.
Department of Biology, Tokyo Metropolitan University, Hachioji, Tokyo, Japan.
Takayuki
T
Horiuchi
Takuya
T
Akiyama
Sumiko
S
Inouye
Teruya
T
Komano
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D018983:DNA Footprinting; D004742:Enhancer Elements, Genetic; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C104848:FruA protein, Myxococcus xanthus; D014157:Transcription Factors