title: The natively disordered loop of Bcl-2 undergoes phosphorylation-dependent conformational change and interacts with Pin1.
abstract: Bcl-2 plays a central role in the regulation of apoptosis. Structural studies of Bcl-2 revealed the presence of a flexible and natively disordered loop that bridges the Bcl-2 homology motifs, BH3 and BH4. This loop is phosphorylated on multiple sites in response to a variety of external stimuli, including the microtubule-targeting drugs, paclitaxel and colchicine. Currently, the underlying molecular mechanism of Bcl-2 phosphorylation and its biological significance remain elusive. In this study, we investigated the molecular characteristics of this anti-apoptotic protein. To this end, we generated synthetic peptides derived from the Bcl-2 loop, and multiple Bcl-2 loop truncation mutants that include the phosphorylation sites. Our results demonstrate that S87 in the flexible loop of Bcl-2 is the primary phosphorylation site for JNK and ERK2, suggesting some sequence or structural specificity for the phosphorylation by these kinases. Our NMR studies and molecular dynamics simulation studies support indicate that phosphorylation of S87 induces a conformational change in the peptide. Finally, we show that the phosphorylated peptides of the Bcl-2 loop can bind Pin1, further substantiating the phosphorylation-mediated conformation change of Bcl-2.
authors.affiliation: Division of Structural and Computational Biology, School of Biological Sciences, Nanyang Technological University, Singapore, Singapore. cbkang@etc.a-star.edu.sg
authors.forename: Congbao
authors.initials: C
authors.lastname: Kang
authors.forename: Nagakumar
authors.initials: N
authors.lastname: Bharatham
authors.forename: Joel
authors.initials: J
authors.lastname: Chia
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Mu
authors.forename: Kwanghee
authors.initials: K
authors.lastname: Baek
authors.forename: Ho Sup
authors.initials: HS
authors.lastname: Yoon
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D019696:Peptidylprolyl Isomerase / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase