Neutron reflectometry and NMR spectroscopy of full-length Bcl-2 protein reveal its membrane localization and conformation.

B-cell lymphoma 2 (Bcl-2) proteins are the main regulators of mitochondrial apoptosis. Anti-apoptotic Bcl-2 proteins possess a hydrophobic tail-anchor enabling them to translocate to their target membrane and to shift into an active conformation where they inhibit pro-apoptotic Bcl-2 proteins to ensure cell survival. To address the unknown molecular basis of their cell-protecting functionality, we used intact human Bcl-2 protein natively residing at the mitochondrial outer membrane and applied neutron reflectometry and NMR spectroscopy.

Bax to the future - A novel, high-yielding approach for purification and expression of full-length Bax protein for structural studies.

Mitochondria-mediated apoptosis (programmed cell death) involves a sophisticated signaling and regulatory network that is regulated by the Bcl-2 protein family. Members of this family have either pro- or anti-apoptotic functions. An important pro-apoptotic member of this family is the cytosolic Bax.

Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization.

Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e.

The oxidized phospholipid PazePC promotes permeabilization of mitochondrial membranes by Bax.

Mitochondria play a crucial role in programmed cell death via the intrinsic apoptotic pathway, which is tightly regulated by the B-cell CLL/lymphoma-2 (Bcl-2) protein family. Intracellular oxidative stress causes the translocation of Bax, a pro-apoptotic family member, to the mitochondrial outer membrane (MOM) where it induces membrane permeabilization. Oxidized phospholipids (OxPls) generated in the MOM during oxidative stress directly affect the onset and progression of mitochondria-mediated apoptosis.

Enthalpy-entropy compensation at play in human copper ion transfer.

Copper (Cu) is an essential trace element but toxic in free form. After cell uptake, Cu is transferred, via direct protein-protein interactions, from the chaperone Atox1 to the Wilson disease protein (WD) for incorporation into Cu-dependent enzymes. Cu binds to a conserved C(1)XXC(2) motif in the chaperone as well as in each of the cytoplasmic metal-binding domains of WD.

Human cytoplasmic copper chaperones Atox1 and CCS exchange copper ions in vitro.

After Ctr1-mediated copper ion (Cu) entry into the human cytoplasm, chaperones Atox1 and CCS deliver Cu to P1B-type ATPases and to superoxide dismutase, respectively, via direct protein-protein interactions. Although the two Cu chaperones are presumed to work along independent pathways, we here assessed cross-reactivity between Atox1 and the first domain of CCS (CCS1) using biochemical and biophysical methods in vitro. By NMR we show that CCS1 is monomeric although it elutes differently from Atox1 in size exclusion chromatography (SEC).

T versus D in the MTCXXC motif of copper transport proteins plays a role in directional metal transport.

To avoid toxicity and control levels of metal ions, organisms have developed specific metal transport systems. In humans, the cytoplasmic Cu chaperone Atox1 delivers Cu to metal-binding domains of ATP7A/B in the Golgi, for incorporation into Cu-dependent proteins. The Cu-binding motif in Atox1, as well as in target Cu-binding domains of ATP7A/B, consists of a MX1CXXC motif where X1 = T.