2ka1 | pdb_00002ka1
Solution NMR structure of BNIP3 transmembrane peptide dimer in detergent micelles
Structural highlights
Function[BNIP3_HUMAN] Apoptosis-inducing protein that can overcome BCL2 suppression. May play a role in repartitioning calcium between the two major intracellular calcium stores in association with BCL2. Involved in mitochondrial quality control via its interaction with SPATA18/MIEAP: in response to mitochondrial damage, participates to mitochondrial protein catabolic process (also named MALM) leading to the degradation of damaged proteins inside mitochondria. The physical interaction of SPATA18/MIEAP, BNIP3 and BNIP3L/NIX at the mitochondrial outer membrane regulates the opening of a pore in the mitochondrial double membrane in order to mediate the translocation of lysosomal proteins from the cytoplasm to the mitochondrial matrix. Plays an important role in the calprotectin (S100A8/A9)-induced cell death pathway.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMutagenesis data suggest that BNIP3 transmembrane domain dimerization depends critically on hydrogen bonding between His 173 and Ser 172, but a recent structural analysis indicates that these residues adopt multiple conformations and are not always hydrogen bonded. We show that in dodecylphosphocholine micelles the structure of the BNIP3 transmembrane domain is modulated by phospholipids and that appropriate reconstitution and lipid titration yield a single set of peptide resonances. NMR structure determination reveals a symmetric dimer in which all interfacial residues, including His 173 and Ser 172, are well-defined. Small residues Ala 176, Gly 180, and Gly 184 allow close approach of essentially ideal helices in a geometry that supports intermonomer hydrogen bond formation between the side chains of His 173 and Ser 172. Bulky residues Ile 177 and Ile 181 pack against small residues of the opposite monomer, and favorable polar backbone-backbone contacts at the interface likely include noncanonical Calpha-H.O=C hydrogen bonds from Gly 180 to Ile 177. Modeling mutations into the structure shows that most deleterious hydrophobic substitutions eliminate the His-Ser hydrogen bond or introduce an intermonomer clash, indicating critical roles for sterics and hydrogen bonding in the sequence dependence of dimerization. Substitutions at most noninterfacial positions do not alter dimerization, but the disruptive effects of substitutions at Ile 183 cannot be rationalized in terms of peptide-peptide contacts and therefore may indicate a role for peptide-detergent or peptide-lipid interactions at this position. Structural basis for dimerization of the BNIP3 transmembrane domain.,Sulistijo ES, Mackenzie KR Biochemistry. 2009 Jun 16;48(23):5106-20. PMID:19415897[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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