title: Complete activation of Bax by a single site mutation.
abstract: Bax translocation from the cytosol to mitochondria culminates a key step by which this protein mediates cell death. Here, we identified two amino acids, L70 and D71, within the BH3 domain of Bax that play a critical role in regulating Bax's cytosolic vs mitochondrial distribution. Individual substitution of these amino acids with alanine resulted in Bax conformational change, oligomerization, localization to mitochondria and cell death. Further mutational analysis indicated that L70 interacts with T174, V177 and A178 of Bax's C-terminal hydrophobic segment, while the negative charge of D71 is required for maintaining Bax in its soluble monomeric state. In summary, we have identified a new regulatory site that controls Bax's subcellular distribution and activation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: H
authors.initials: H
authors.lastname: Zhou
authors.forename: Q
authors.initials: Q
authors.lastname: Hou
authors.forename: J L
authors.initials: JL
authors.lastname: Hansen
authors.forename: Y-T
authors.initials: YT
authors.lastname: Hsu
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D003600:Cytosol / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D007930:Leucine / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation / Q000235:genetics*; D051028:bcl-2-Associated X Protein / Q000235:genetics* / Q000378:metabolism*; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C494826:BAX protein, human; C494811:BCL2L1 protein, human; D024101:Mitochondrial Proteins; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D001224:Aspartic Acid; D007930:Leucine