Insights into the structural basis of the GADD45beta-mediated inactivation of the JNK kinase, MKK7/JNKK2.
NF-kappaB/Rel factors control programmed cell death (PCD), and this control is crucial to oncogenesis, cancer chemoresistance, and antagonism of tumor necrosis factor (TNF) alpha-induced killing. With TNFalpha, NF-kappaB-mediated protection involves suppression of the c-Jun-N-terminal kinase (JNK) cascade, and we have identified Gadd45beta, a member of the Gadd45 family, as a pivotal effector of this activity of NF-kappaB. Inhibition of TNFalpha-induced JNK signaling by Gadd45beta depends on direct targeting of the JNK kinase, MKK7/JNKK2. The mechanism by which Gadd45beta blunts MKK7, however, is unknown. Here we show that Gadd45beta is a structured protein with a predicted four-stranded beta-sheet core, five alpha-helices, and two acidic loops. Association of Gadd45beta with MKK7 involves a network of interactions mediated by its putative helices alpha3 and alpha4 and loops 1 and 2. Whereas alpha3 appears to primarily mediate docking to MKK7, loop 1 and alpha4-loop 2 seemingly afford kinase inactivation by engaging the ATP-binding site and causing conformational changes that impede catalytic function. These data provide a basis for Gadd45beta-mediated blockade of MKK7, and ultimately, TNFalpha-induced PCD. They also have important implications for treatment of widespread diseases.
Papa
Salvatore
S
The Ben May Institute for Cancer Research, University of Chicago, Chicago, Illinois 60637, USA.
Monti
Simona M
SM
Vitale
Rosa Maria
RM
Bubici
Concetta
C
Jayawardena
Shanthi
S
Alvarez
Kellean
K
De Smaele
Enrico
E
Dathan
Nina
N
Pedone
Carlo
C
Ruvo
Menotti
M
Franzoso
Guido
G
D000595:Amino Acid Sequence; D000943:Antigens, Differentiation / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D048688:MAP Kinase Kinase 7 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology; D013329:Structure-Activity Relationship; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D000097642:GADD45 Proteins
D000943:Antigens, Differentiation; D048688:MAP Kinase Kinase 7; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C086470:GADD45B protein, human; D000097642:GADD45 Proteins; C482569:MAP2K7 protein, human