Molecular Basis of Bcl-xL’s Target Recognition Versatility Revealed by the Structure of Bcl-xL in Complex with the BH3 Domain of Beclin-1

Feng, Wei; Huang, Siyi; Wu, Hao; Zhang, Mingjie

doi:10.1016/j.jmb.2007.06.069

Cited by 166 publications

(202 citation statements)

References 56 publications

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“…Despite a similar strategy among Bcl-2 family proteins of BH3 domain binding to a surface hydrophobic groove, there is a high degree of specificity in the interactions (42,47). Furthermore, the binding pockets of some Bcl-2 family members, including Bcl-x L , have considerable conformational flexibility to accommodate different BH3 domains (48,49). Such structural flexibility may explain the interaction with the BH3-like domains in the InsP 3 R.…”

Section: Discussionmentioning

confidence: 99%

Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability

Yang

Vais

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Antiapoptotic Bcl-2 family members interact with inositol trisphosphate receptor (InsP 3 R) Ca 2+ release channels in the endoplasmic reticulum to modulate Ca 2+ signals that affect cell viability. However, the molecular details and consequences of their interactions are unclear. Here, we found that Bcl-x L activates single InsP 3 R channels with a biphasic concentration dependence. The Bcl-x L Bcl-2 homology 3 (BH3) domain-binding pocket mediates both high-affinity channel activation and low-affinity inhibition. Bcl-x L activates channel gating by binding to two BH3 domain-like helices in the channel carboxyl terminus, whereas inhibition requires binding to one of them and to a previously identified Bcl-2 interaction site in the channelcoupling domain. Disruption of these interactions diminishes cell viability and sensitizes cells to apoptotic stimuli. Our results identify BH3-like domains in an ion channel and they provide a unifying model of the effects of antiapoptotic Bcl-2 proteins on the InsP 3 R that play critical roles in Ca 2+ signaling and cell viability.T he inositol trisphosphate receptors (InsP 3 R) are a family of intracellular cation channels that release Ca 2+ from the endoplasmic reticulum (ER) in response to a variety of extracellular stimuli (1). Three InsP 3 R isoforms are ubiquitously expressed and regulate diverse cell processes, including cell viability (1). Activation of the channels by InsP 3 elicits changes in cytoplasmic Ca 2+ concentration ([Ca 2+ ] i ) that provide versatile signals to regulate molecular processes with high spatial and temporal fidelity (1). Regions of close proximity to mitochondria enable localized Ca 2+ release events to be transduced to mitochondria (2, 3). Ca 2+ released from the ER during cell stimulation modulates activities of effector molecules and is taken up by mitochondria to stimulate oxidative phosphorylation and enhance ATP production (4-6) to match energetic supply with enhanced demand. In addition, cells in vivo are constantly exposed to low levels of circulating hormones, transmitters, and growth factors that bind to plasma membrane receptors to provide a background level of cytoplasmic InsP 3 (7) that generates low-level stochastic InsP 3 R-mediated localized or propagating [Ca 2+ ] i signals (8-10). Such signals also play an important role in maintenance of cellular bioenergetics (8). Nevertheless, under conditions of cell stress the close proximity of mitochondria to Ca 2+ release sites may result in mitochondrial Ca 2+ overload and initiate Ca 2+ -dependent forms of cell death, including necrosis and apoptosis (11-13). It has been suggested that high levels of ER Ca 2+ (14-16) and enhanced activity of the InsP 3 R (17-19) promote cell death by providing a higher quantity of released Ca 2+ to mitochondria (3,20,21).Protein interactions modulate the magnitude and quality of InsP 3 R-mediated [Ca 2+ ] i signals that regulate apoptosis and cell viability. Notable in this regard is the Bcl-2 protein family. Proapoptotic Bcl-2-related proteins Bax ...

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Section: Discussionmentioning

confidence: 99%

Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability

Yang

Vais

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…The sufficiency of the Beclin-1 BH3-domain alone to induce apoptosis through its binding to Bcl-xL (Maiuri et al, 2007a, b) has raised the suggestion that there are counteracting regulatory sequences that may normally prevent the BH3 motif in Beclin-1 from activating apoptosis when present within the full-length protein, as discussed by Levine et al (2008). Different binding interactions for the BH3-domain of Beclin-1 bound to Bcl-xL compared with other BH3-domains were also reported (Feng et al, 2007;Oberstein et al, 2007). Moreover, Beclin-1 is bound to many other proteins in addition to Bcl-2 family members (Vps34 (Furuya et al, 2005), UVRAG (Liang et al, 2006;Takahashi et al, 2007), Bif1 (Takahashi et al, 2007) Ambra (Fimia et al, 2007)), which may further obscure the function of the BH3-domain.…”

Section: Discussionmentioning

confidence: 99%

“…BH3-only proteins are pro-apoptotic regulators of apoptosis, the binding of which to anti-apoptotic Bcl-2 members is one mechanism of facilitating the activation of Bax/Bak, crucial mediators of the mitochondrial pathway of apoptosis (Scorrano and Korsmeyer, 2003;Certo et al, 2006;Adams and Cory, 2007). Like other BH3-only proteins, the BH3 domain of Beclin-1 binds to anti-apoptotic Bcl-2 family proteins within their hydrophobic groove (Feng et al, 2007;Oberstein et al, 2007;Maiuri et al, 2007b;Ku et al, 2008;Sinha et al, 2008). Thus, in reconstituted systems it is displaced from Bcl-2/-xL/-w by Bad, tBid or the BH3-mimetic compound, ABT737, though not by Bax/Bak (Erlich et al, 2007;Maiuri et al, 2007b).…”

Section: Introductionmentioning

confidence: 99%

Bcl-2 complexed with Beclin-1 maintains full anti-apoptotic function

et al. 2009

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The binding of Bcl-2 to Beclin-1 reduces Beclin-1's capacity to induce autophagy. Here, we have tested whether the interaction is reciprocated by loss of Bcl-2's anti-apoptotic function. We targeted Bcl-2 to mitochondria or endoplasmic reticulum (ER) and induced apoptosis using several apoptotic stimuli that initiate ER and/or mitochondrial signaling pathways (UV radiation, TNF and cycloheximide, staurosporine, thapsigargin and tunicamycin). When Beclin-1 and Bcl-2 were expressed together in HeLa cells, Beclin-1 (but not Beclin-1 lacking the Bcl-2-binding domain) followed Bcl-2 to the appropriate organelle with complete or near-complete overlap (comprising 60 and 30% of cells, respectively). The interaction between Beclin-1 and Bcl-2 was verified by immunoprecipitation, and a membrane-proximate localization of Beclin-1 was shown by immunoelectron microscopy. Apoptosis was followed by measuring changes in nuclear morphology, caspase-3 activity, poly-ADP-ribose polymerase cleavage or punctation of mRFP-Bax on mitochondria. Binding of Beclin-1 to Bcl-2 did not modify apoptosis irrespective of Bcl-2 concentration, location or apoptotic stimulus. A similar result was obtained in Atg5À/À cells that are autophagy-deficient, arguing against compensation for the loss of protection by Bcl-2 by autophagy-mediated survival induced by Beclin-1. Hence, although Beclin-1 contains a BH3-only motif typical of pro-apoptotic proteins, it is a negligible modulator of Bcl-2's anti-apoptotic function.

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“…41 Two complementary approaches, structural analyses and functional analyses in the background of appropriate mutations, have conclusively proven that Beclin 1 possesses a functional BH3 domain. The structural evidence obtained from molecular modeling, 16 crystal structures of Bcl-X L complexed to a peptide corresponding to the BH3 domain of Beclin 1, 41 and HSQC NMR spectra of 15 N-labeled Bcl-X L measured in the presence and absence of saturating amounts of Beclin 1 BH3 domain peptides 42 demonstrated that the amphipathic BH3 helix of Beclin 1 binds to a conserved hydrophobic groove of Bcl-X L . These findings are similar to previously determined interactions between Bcl-X L -and other BH3 domains.…”

Section: Beclin 1 As a Novel Bh3-only Proteinmentioning

confidence: 98%

Bcl-2 family members: Dual regulators of apoptosis and autophagy

Levine¹,

Sinha²,

Kroemer³

2008

Autophagy

751

608

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Molecular Basis of Bcl-xL’s Target Recognition Versatility Revealed by the Structure of Bcl-xL in Complex with the BH3 Domain of Beclin-1

Cited by 166 publications

References 56 publications

Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability

Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability

Bcl-2 complexed with Beclin-1 maintains full anti-apoptotic function

Bcl-2 family members: Dual regulators of apoptosis and autophagy

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Molecular Basis of Bcl-xL’s Target Recognition Versatility Revealed by the Structure of Bcl-xL in Complex with the BH3 Domain of Beclin-1

Cited by 166 publications

References 56 publications

Biphasic regulation of InsP 3 receptor gating by dual Ca 2+ release channel BH3-like domains mediates Bcl-x L control of cell viability

Biphasic regulation of InsP 3 receptor gating by dual Ca 2+ release channel BH3-like domains mediates Bcl-x L control of cell viability

Bcl-2 complexed with Beclin-1 maintains full anti-apoptotic function

Bcl-2 family members: Dual regulators of apoptosis and autophagy

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Product

Resources

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Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability

Biphasic regulation of InsP ₃ receptor gating by dual Ca ²⁺ release channel BH3-like domains mediates Bcl-x _L control of cell viability