Oyster IKK-like protein shares structural and functional properties with its mammalian homologues.
In our search for genes involved in oyster immunity we isolated a cDNA encoding a polypeptide closely related to the mammalian IkappaB kinase (IKK) family. IKK proteins play a central role in cell signaling by regulating nuclear factor-kappaB (NF-kappaB) activation. We report here the cloning of an oyster IKK-like protein (oIKK) which possesses the characteristic organization of the mammalian IKK proteins, namely an amino-terminal kinase domain followed by a leucine zipper region and a carboxyl-terminal helix-loop-helix motif. When transfected into human cell lines, oIKK activated the expression of NF-kappaB-controlled reporter gene, whereas transfections with mutants of oIKK deleted within the kinase domain or within the helix-loop-helix motif respectively abolished and greatly reduced reporter gene activation. These results indicate that oIKK can replace the hIKK-alpha in catalyzing NF-kappaB nuclear translocation, and in triggering gene expression. Our results sustain the concept of an evolutionarily conserved signaling machinery in which IKK plays a major role.
Escoubas
J M
JM
Laboratoire de Défense et Résistance chez les Invertébrés Marins, Université de Montpellier II, France. jmescoub@ifremer.fr
Briant
L
L
Montagnani
C
C
Hez
S
S
Devaux
C
C
Roch
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D020134:Catalytic Domain; D018257:Helix-Loop-Helix Motifs; D051550:I-kappa B Kinase; D008969:Molecular Sequence Data; D010125:Ostreidae / Q000201:enzymology / Q000235:genetics* / Q000276:immunology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014018:Tissue Distribution
D012333:RNA, Messenger; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D051550:I-kappa B Kinase