Poster abstracts

Poster number 4 submitted by Ryan Hard

Screening of One-Bead-One-Compound Peptide Libraries for the Sequence Specificity of Tandem BRCT Domains

Ryan L. Hard (Ohio State Biochemistry Program, The Ohio State University)

Abstract:
Tandem BRCA1 C-Terminal (BRCT) domains are phosphopeptide binding modules that can interact with either internal or C-terminal phosphoserine motifs. There are 16 tandem BRCT domains found in 12 human proteins, most of which are involved in the DNA damage response pathway and cell cycle regulation. Knowledge of the types of phosphoserine sequences recognized by each BRCT domain tandem would aid in finding the in vivo binding partners of BRCT domain-containing proteins. The one-bead-one-compound (OBOC) combinatorial peptide library approach allows for the determination of individual binding sequences to proteins of interest, which can be compiled and analyzed to determine the binding specificity of a particular protein domain. To study the binding specificity of tandem BRCT domains, we synthesized an OBOC phosphopeptide library which presented free C-terminal peptides on the bead surface. We also synthesized an OBOC phosphopeptide library which presented peptides in the normal N-to-C-terminal orientation. Upon screening every tandem BRCT domain found in the human proteome, it was found that only a subset of BRCT tandems recognize relatively short and well-defined phosphopeptide motifs. Furthermore, the C-terminal BRCT domain tandem of Pax Transactivation Domain-Interacting Protein (PTIP) recognizes a novel dual phosphoserine motif.

Keywords: BRCT Domain, One-Bead-One-Compound Peptide Library, Binding Specificity