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
Volume427
Issue15
Pagination2468-90
Date Published2015 Jul 31
ISSN1089-8638
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
Abstract

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.

DOI10.1016/j.jmb.2015.05.015
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