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PDBsum entry 6fbx
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Cell Death Dis
9:967
(2018)
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PubMed id:
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A structural investigation of NRZ mediated apoptosis regulation in zebrafish.
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C.D.Suraweera,
S.Caria,
M.Järvå,
M.G.Hinds,
M.Kvansakul.
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ABSTRACT
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Bcl-2 family proteins play a crucial role in regulating apoptosis, a process
critical for development, eliminating damaged or infected cells, host-pathogen
interactions and in disease. Dysregulation of Bcl-2 proteins elicits an
expansive cell survival mechanism promoting cell migration, invasion and
metastasis. Through a network of intra-family protein-protein interactions Bcl-2
family members regulate the release of cell death factors from mitochondria. NRZ
is a novel zebrafish pro-survival Bcl-2 orthologue resident on mitochondria and
the endoplasmic reticulum (ER). However, the mechanism of NRZ apoptosis
inhibition has not yet been clarified. Here we examined the interactions of NRZ
with pro-apoptotic members of the Bcl-2 family using a combination of isothermal
calorimetry and mutational analysis of NRZ. We show that NRZ binds almost all
zebrafish pro-apoptotic proteins and displays a broad range of affinities.
Furthermore, we define the structural basis for apoptosis inhibition of NRZ by
solving the crystal structure of both apo-NRZ and a holo form bound to a peptide
spanning the binding motif of the pro-apoptotic zBad, a BH3-only protein
orthologous to mammalian Bad. The crystal structure of NRZ revealed that it
adopts the conserved Bcl-2 like fold observed for other cellular pro-survival
Bcl-2 proteins and employs the canonical ligand binding groove to bind Bad BH3
peptide. NRZ engagement of Bad BH3 involves the canonical ionic interaction
between NRZ R86 and Bad D104 and an additional ionic interaction between NRZ D79
and Bad R100, and substitution of either NRZ R86 or D79 to Ala reduces the
binding to Bad BH3 tenfold or more. Our findings provide a detailed mechanistic
understanding for NRZ mediated anti-apoptotic activity in zebrafish by revealing
binding to both Bad and Noxa, suggesting that NRZ is likely to occupy a unique
mechanistic role in zebrafish apoptosis regulation by acting as a highly
promiscuous pro-apoptotic Bcl-2 binder.
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');
}
}
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