title: Self-regulated cleavage of the mitochondrial intramembrane-cleaving protease PARL yields Pbeta, a nuclear-targeted peptide.
abstract: Regulated intramembrane proteolysis (RIP) is an emerging paradigm in signal transduction. RIP is mediated by intramembrane-cleaving proteases (I-CliPs), which liberate biologically active nuclear or secreted domains from their membrane-tethered precursor proteins. The yeast Pcp1p/Rbd1p protein is a Rhomboid-like I-CliP that regulates mitochondrial membrane remodeling and fusion through cleavage of Mgm1p, a regulator of these essential activities. Although this ancient function is conserved in PARL (Presenilins-associated Rhomboid-like protein), the mammalian ortholog of Pcp1p/Rbd1p, the two proteins show a strong divergence at their N termini. However, the N terminus of PARL is significantly conserved among vertebrates, particularly among mammals, suggesting that this domain evolved a distinct but still unknown function. Here, we show that the cytosolic N-terminal domain of PARL is cleaved at positions 52-53 (alpha-site) and 77-78 (beta-site). Whereas alpha-cleavage is constitutive and removes the mitochondrial targeting sequence, beta-cleavage appears to be developmentally controlled and dependent on PARL I-CliP activity supplied in trans. The beta-cleavage of PARL liberates Pbeta, a nuclear targeted peptide whose sequence is conserved only in mammals. Thus, in addition to its evolutionarily conserved function in regulating mitochondrial dynamics, PARL might mediate a mammalian-specific, developmentally regulated mitochondria-to-nuclei signaling through regulated proteolysis of its N terminus and release of the Pbeta peptide.
authors.affiliation: Centre de Recherche Robert Giffard, l'Université Laval, G1J 2G3 Quebec, Canada.
authors.forename: Attila
authors.initials: A
authors.lastname: Sík
authors.forename: Brent J
authors.initials: BJ
authors.lastname: Passer
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Luca
authors.initials: L
authors.lastname: Pellegrini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D045726:Metalloproteases / Q000737:chemistry* / Q000378:metabolism*; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000378:metabolism*; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011233:Precipitin Tests; D053764:Presenilin-1; D017434:Protein Structure, Tertiary; D051381:Rats; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D018797:Cell Cycle Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C508853:PSEN1 protein, human; D010455:Peptides; D053764:Presenilin-1; D029702:Schizosaccharomyces pombe Proteins; C454082:pcp1 protein, S pombe; D049452:Green Fluorescent Proteins; D045726:Metalloproteases; C485223:PARL protein, human