YaeL proteolysis of RseA is controlled by the PDZ domain of YaeL and a Gln-rich region of RseA.
sigmaE is an alternative sigma factor involved in a pathway of extracytoplasmic stress responses in Escherichia coli. Under normal growth conditions, sigmaE activity is down-regulated by the membrane-bound anti-sigmaE protein, RseA. Extracytoplasmic stress signals induce degradation of RseA by two successive proteolytic events: DegS-catalyzed first cleavage at a periplasmic site followed by YaeL-mediated second proteolysis at an intramembrane region. Normally, the second reaction (site-2 proteolysis) only occurs after the first cleavage (site-1 cleavage). Here, we show that YaeL variants with the periplasmic PDZ domain deleted or mutated allows unregulated cleavage of RseA and consequent sigmaE activation. It was also found that a glutamine-rich region in the periplasmic domain of RseA was required for the avoidance of the YaeL-mediated proteolysis in the absence of site-1 cleavage. These results indicate that multiple negative elements both in the enzyme (PDZ domain) and in the substrate (glutamine-rich region) determine the strict dependence of the site-2 proteolysis on the site-1 cleavage.
Kanehara
Kazue
K
Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
Ito
Koreaki
K
Akiyama
Yoshinori
Y
D000595:Amino Acid Sequence; D001665:Binding Sites; D010450:Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005816:Genetic Complementation Test; D005973:Glutamine; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*
D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C433802:RseA protein, E coli; D014157:Transcription Factors; D005973:Glutamine; D010450:Endopeptidases; C440001:RseP protein, E coli