Poster Presentation The 45th Lorne Conference on Protein Structure and Function 2020

The structural details of the interaction of single-stranded DNA- binding protein hSSB2 (NABP1/OBFC2A) with UV-damaged DNA (#506)

Teegan Lawson 1 , Serene El-Kamand 1 , Didier Boucher 2 , Duc Cong Duong 1 , Ruvini Kariawasam 1 , Alexandre M.J.J Bonvin 3 , Derek J Richard 2 , Roland Gamsjaeger 1 , Liza Cubeddu 1
  1. School of Science and health, Western Sydney University , Sydney, NSW, Australia
  2. Genome Stability Laboratory, Cancer and Ageing Research Program, Institute of Health and Biomedical Innovation, Translational Research Institute,, Queensland University of Technology, , Woolloongabba, , QLD
  3. Bijvoet Centre for Biomolecular Research , Utrecht University, Utrecht, The Netherlands

Single-stranded DNA-binding proteins (SSBs) are required for all known DNA metabolic event such as DNA replication, recombination and repair. While a wealth of structural and functional data is available on the essential human SSB, hSSB1 (NABP2/OBFC2B), the close homolog hSSB2 (NABP1/OBFC2A) remains relatively uncharacterised. Both SSBs possess a well-structured OB (oligonucleotide/oligosaccharide-binding) domain which is able to recognise single-stranded DNA (ssDNA) and a flexible carboxyl-tail implicated in the interaction with other proteins. Despite the high sequence similarity of the OB domain, several recent studies have revealed distinct differences between hSSB1 and hSSB2. In this study, we were able to show that hSSB2 is involved in the nucleotide excision repair (NER) pathway and is able to recognise cyclobutane pyrimidine dimers (CPD) that form in cells as a consequence of UV damage. Using a combination of BLI and NMR, we determined the molecular details of hSSB2 binding to CPD-containing ssDNA confirming the role of four key aromatic residues in hSSB2 (W59, Y78, W82 and Y89) that are also conserved in hSSB1. From a molecular perspective, our structural data demonstrate that ssDNA recognition of hSSB2 is highly similar to hSSB1 indicating that one might be able to compensate for the other in initial ssDNA binding events.