title: Identification of a novel Mcl-1 protein binding motif.
abstract: Recent characterization of Mcl-1 as the primary anti-apoptotic Bcl-2 family member expressed in solid tumors, coupled with its ability to enable therapeutic resistance, has provided the impetus for further study into how Mcl-1 is involved in apoptosis signaling. Here, we employ Sabutoclax, a potent and effective Mcl-1 antagonist, as a competing agent to screen a randomized 12-residue phage display library for peptides that bind strongly to the Bcl-2 homology 3 (BH3) binding groove of Mcl-1. Although the screen identified a number of α-helical peptides with canonical BH3 domain sequences, it also isolated a pair of unique peptide sequences. These sequences exhibit a reverse organization of conserved hydrophobic and acidic residues when compared with canonical BH3 sequences, and we therefore refer to them as reverse BH3 (rBH3) peptides. Furthermore, studies of the rBH3 peptides using NMR spectroscopy, fluorescence polarization displacement assays, and alanine scanning data all suggest that they bind to the BH3 binding groove of Mcl-1 selectively over Bcl-x(L). A search for proteins containing the rBH3 motif has identified a number of interesting Mcl-1 protein partners, some of which have previously been associated with apoptosis regulation involving Mcl-1. These findings provide insights into the development of more specific Mcl-1 antagonists and open the way to the identification of a previously unknown family of apoptosis-regulating and Mcl-1 interacting proteins.
authors.affiliation: Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Placzek
authors.forename: Mattia
authors.initials: M
authors.lastname: Sturlese
authors.forename: Bainan
authors.initials: B
authors.lastname: Wu
authors.forename: Jason F
authors.initials: JF
authors.lastname: Cellitti
authors.forename: Jun
authors.initials: J
authors.lastname: Wei
authors.forename: Maurizio
authors.initials: M
authors.lastname: Pellecchia
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D045744:Cell Line, Tumor; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D051020:bcl-X Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C474007:Bax protein (53-86); C494812:Bcl2l1 protein, mouse; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein