Structural and energetic aspects of Grb2-SH2 domain-swapping

Benfield, Aaron P.; Whiddon, Benjamin B.; Clements, John H.; Martin, Stephen F.

doi:10.1016/j.abb.2007.03.010

Cited by 33 publications

(47 citation statements)

References 37 publications

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“…Over the past decade or so, oligomerization of proteins through domain-swapping has emerged as a common mechanism for the assembly of proteins into higher-order structures [83–88]. From a thermodynamic standpoint, such intermolecular association would allow two participating monomers to bury additional surface area culminating in not only enhanced stability but also providing a greater interacting molecular surface for further oligomerization.…”

Section: Resultsmentioning

confidence: 99%

Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor

Bhat

Kurouski

Olenick

et al. 2012

Archives of Biochemistry and Biophysics

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Solution pH is believed to serve as an intricate regulatory switch in the induction of apoptosis central to embryonic development and cellular homeostasis. Herein, using an array of biophysical techniques, we provide evidence that acidic pH promotes the assembly of BclXL apoptotic repressor into a megaldalton oligomer with a plume-like appearance and harboring structural features characteristic of a molten globule. Strikingly, our data reveal that pH tightly modulates not only oligomerization but also ligand binding and membrane insertion of BclXL in a highly subtle manner. Thus, while oligomerization and the accompanying molten globular content of BclXL is least favorable at pH 6, both of these structural features become more pronounced under acidic and alkaline conditions. However, membrane insertion of BclXL appears to be predominantly favored under acidic conditions. In a remarkable contrast, while ligand binding to BclXL optimally occurs at pH 6, it is diminished by an order of magnitude at lower and higher pH. This reciprocal relationship between BclXL oligomerization and ligand binding lends new insights into how pH modulates functional versatility of a key apoptotic regulator and strongly argues that the molten globule may serve as an intermediate primed for membrane insertion in response to apoptotic cues.

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Section: Resultsmentioning

confidence: 99%

Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor

Bhat

Kurouski

Olenick

et al. 2012

Archives of Biochemistry and Biophysics

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“…We further identified (http://scansite.mit.edu) the growth factor receptor-binding protein, 2-Src homology 2 (Grb2-SH2, TLKDIVEYYNDSNGS) domain, within the ZAG sequence. The Grb2-SH2 domain has been described as docking site for activated receptors and, therefore, is important in the oncogenic Ras signal transduction pathway (Lung and Tsai, 2003;Benfield et al, 2007). We thus speculate that ZAG might exert its effect on TGF-b and Ras/ERK signaling through the Grb2-SH2 domain.…”

Section: Discussionmentioning

confidence: 98%

AZGP1 is a tumor suppressor in pancreatic cancer inducing mesenchymal-to-epithelial transdifferentiation by inhibiting TGF-β-mediated ERK signaling

et al. 2010

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Epithelial-to-mesenchymal transdifferentiation (EMT) mediated by transforming growth factor-b (TGF-b) signaling leads to aggressive cancer progression. In this study, we identified zinc-a2-glycoprotein (AZGP1, ZAG) as a tumor suppressor in pancreatic ductal adenocarcinoma whose expression is lost due to histone deacetylation. In vitro, ZAG silencing strikingly increased invasiveness of pancreatic cancer cells accompanied by the induction of a mesenchymal phenotype. Expression analysis of a set of EMT markers showed an increase in the expression of mesenchymal markers (vimentin (VIM) and integrin-a5) and a concomitant reduction in the expression of epithelial markers (cadherin 1 (CDH1), desmoplakin and keratin-19). Blockade of endogenous TGF-b signaling inhibited these morphological changes and the downregulation of CDH1, as elicited by ZAG silencing. In a ZAG-negative cell line, human recombinant ZAG (rZAG) specifically inhibited exogenous TGF-b-mediated tumor cell invasion and VIM expression. Furthermore, rZAG blocked TGF-b-mediated ERK2 phosphorylation. PCR array analysis revealed that ZAG-induced epithelial transdifferentiation was accompanied by a series of concerted cellular events including a shift in the energy metabolism and prosurvival signals. Thus, epigenetically regulated ZAG is a novel tumor suppressor essential for maintaining an epithelial phenotype.

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“…In particular, oligomerization of BclXL appears to be driven through domain-swapping such that the TM domain of one monomer occupies the canonical hydrophobic groove within the other monomer and vice versa in a trans-fashion. Over the past decade or so, homodimerization of proteins through domain-swapping has emerged as a common mechanism for protein oligomerization 60–65 . From a thermodynamic standpoint, such intermolecular association would allow two participating monomers to bury additional surface area culminating in not only enhanced stability but also providing a greater interacting molecular surface for further oligomerization (Figure 10a).…”

Section: Discussionmentioning

confidence: 99%

Ligand Binding and Membrane Insertion Compete with Oligomerization of the BclXL Apoptotic Repressor

Bhat

McDonald

Mikles

et al. 2012

Journal of Molecular Biology

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BclXL apoptotic repressor plays a central role in determining the fate of cells to live or die during physiological processes such as embryonic development and tissue homeostasis. Herein, using a myriad of biophysical techniques, we provide evidence that ligand binding and membrane insertion compete with oligomerization of BclXL in solution. Of particular importance is the observation that such oligomerization is driven by the intermolecular binding of its C-terminal transmembrane (TM) domain to the canonical hydrophobic groove in a domain-swapped trans-fashion, whereby the TM domain of one monomer occupies the canonical hydrophobic groove within the other monomer and vice versa. Binding of BH3 ligands to the canonical hydrophobic groove displaces the TM domain in a competitive manner allowing BclXL to dissociate into monomers upon hetero-association. Remarkably, spontaneous insertion of BclXL into DMPC/DHPC bicelles results in a dramatic conformational change such that it can no longer recognize the BH3 ligands in what has come to be known as the “hit-and-run” mechanism. Collectively, our data suggest that oligomerization of a key apoptotic repressor serves as an allosteric switch that fine tunes its ligand binding and membrane insertion pertinent to the regulation of apoptotic machinery.

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Structural and energetic aspects of Grb2-SH2 domain-swapping

Cited by 33 publications

References 37 publications

Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor

Acidic pH promotes oligomerization and membrane insertion of the BclXL apoptotic repressor

AZGP1 is a tumor suppressor in pancreatic cancer inducing mesenchymal-to-epithelial transdifferentiation by inhibiting TGF-β-mediated ERK signaling

Ligand Binding and Membrane Insertion Compete with Oligomerization of the BclXL Apoptotic Repressor

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