Talk abstracts

Talk on Wednesday 04:45-05:00pm submitted by Brandon Crowe

Structural basis for high-affinity binding of LEDGF PWWP to mononucleosomes

Brandon Crowe (Department of Chemistry and Biochemistry, The Ohio State University), Jocelyn Eidahl (Department of Pharmacy, The Ohio State University), Mamuka Kvaratskhelia (Department of Pharmacy, The Ohio State University), Mark Foster (Department of Chemistry and Biochemistry, The Ohio State University)

Abstract:
Lens epithelium derived growth factor p75 (LEDGF/p75) is a transcription factor that promotes resistance to stress induced cell death. LEDGF is a large multi domain protein containing a PWWP domain, two AT hook DNA binding domains, and a C-terminal integrase binding domain (IBD). HIV-1 has been shown to hijack LEDGF in order to facilitate integration into the host genome, as LEDGF knock-out cell lines reduce the ability of HIV-1 to infect cells by more than 95%. LEDGF functions as a bimodal tether for HIV-1 integration. The IBD interacts with the preintegration complex of HIV-1, whereas the PWWP domain and AT hooks bind cellular chromatin. The molecular basis for the integrase-LEDGF interaction is understood from structural studies, but not the mechanism of chromatin binding. We have determined the solution structure of the N-terminal PWWP domain and monitored binding to the histone H3 tail containing trimethylated Lys 36 (H3K36me3) and DNA by nuclear magnetic resonance (NMR). Results reveal two distinct binding interfaces of LEDGF PWWP: a well-defined hydrophobic cavity, which selectively interacts with the H3K36me3 peptide and adjacent basic surface, which non-specifically binds DNA. Binding studies on the PWWP domain with DNA alone, H3K36me3 alone, and reconstituted nucleosomes reveal cooperativity between DNA and peptide binding activities. These data allows us to make structural hypotheses for the direct interaction of LEDGF/p75 to chromatin and thus the targeting of HIV-1 integration that occurs in vivo.

References:
Eidahl, J.O., Crowe, B.L., et. al. (2013) Structural basis for high-affinity binding of LEDGF PWWP to mononucleosomes. Nucleic Acids Res 41, 3924-3936.

Keywords: HIV, LEDGF p75, NMR solution structure