Locating Herpesvirus Bcl-2 Homologs in the Specificity Landscape of Anti-Apoptotic Bcl-2 Proteins.

TitleLocating Herpesvirus Bcl-2 Homologs in the Specificity Landscape of Anti-Apoptotic Bcl-2 Proteins.
Publication TypeJournal Article
Year of Publication2015
AuthorsFoight GWink, Keating AE
JournalJ Mol Biol
Date Published2015 Jul 31
KeywordsAmino Acid Sequence, Humans, Microarray Analysis, Models, Molecular, Molecular Sequence Data, Oncogene Proteins, Peptide Fragments, Protein Binding, Protein Interaction Domains and Motifs, Protein Interaction Maps, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Sequence Homology, Substrate Specificity, Viral Proteins

Viral homologs of the anti-apoptotic Bcl-2 proteins are highly diverged from their mammalian counterparts, yet they perform overlapping functions by binding and inhibiting BH3 (Bcl-2 homology 3)-motif-containing proteins. We investigated the BH3 binding properties of the herpesvirus Bcl-2 homologs KSBcl-2, BHRF1, and M11, as they relate to those of the human Bcl-2 homologs Mcl-1, Bfl-1, Bcl-w, Bcl-xL, and Bcl-2. Analysis of the sequence and structure of the BH3 binding grooves showed that, despite low sequence identity, M11 has structural similarities to Bcl-xL, Bcl-2, and Bcl-w. BHRF1 and KSBcl-2 are more structurally similar to Mcl-1 than to the other human proteins. Binding to human BH3-like peptides showed that KSBcl-2 has similar specificity to Mcl-1, and BHRF1 has a restricted binding profile; M11 binding preferences are distinct from those of Bcl-xL, Bcl-2, and Bcl-w. Because KSBcl-2 and BHRF1 are from human herpesviruses associated with malignancies, we screened computationally designed BH3 peptide libraries using bacterial surface display to identify selective binders of KSBcl-2 or BHRF1. The resulting peptides bound to KSBcl-2 and BHRF1 in preference to Bfl-1, Bcl-w, Bcl-xL, and Bcl-2 but showed only modest specificity over Mcl-1. Rational mutagenesis increased specificity against Mcl-1, resulting in a peptide with a dissociation constant of 2.9nM for binding to KSBcl-2 and >1000-fold specificity over other Bcl-2 proteins, as well as a peptide with >70-fold specificity for BHRF1. In addition to providing new insights into viral Bcl-2 binding specificity, this study will inform future work analyzing the interaction properties of homologous binding domains and designing specific protein interaction partners.

Alternate JournalJ. Mol. Biol.
PubMed ID26009469
PubMed Central IDPMC4520770
Grant ListR01 GM084181 / GM / NIGMS NIH HHS / United States
R01GM110048 / GM / NIGMS NIH HHS / United States
T32 GM007287 / GM / NIGMS NIH HHS / United States