Structure-specific recognition protein-1 (SSRP1) is an elongated homodimer that binds histones

Gabriele Marciano*, Stefano Da Vela, Giancarlo Tria, Dmitri I. Svergun, Olwyn Byron, Danny T. Huang

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Web of Science)

Abstract

The histone chaperone complex facilitates chromatin transcription (FACT) plays important roles in DNA repair, replication, and transcription. In the formation of this complex, structure-specific recognition protein-1 (SSRP1) heterodimerizes with suppressor of Ty 16 (SPT16). SSRP1 also has SPT16-independent functions, but how SSRP1 functions alone remains elusive. Here, using analytical ultracentrifugation (AUC) and small-angle X-ray scattering (SAXS) techniques, we characterized human SSRP1 and that from the amoeba Dictyostelium discoideum and show that both orthologs form an elongated homodimer in solution. We found that substitutions in the SSRP1 pleckstrin homology domain known to bind SPT16 also disrupt SSRP1 homodimerization. Moreover, AUC and SAXS analyses revealed that SSRP1 homodimerization and heterodimerization with SPT16 (resulting in FACT) involve the same SSRP1 surface, namely the PH2 region, and that the FACT complex contains only one molecule of SSRP1. These observations suggest that SSRP1 homo- and heterodimerization might be mutually exclusive. Moreover, isothermal titration calorimetry analyses disclosed that SSRP1 binds both histones H2A-H2B and H3-H4 and that disruption of SSRP1 homodimerization decreases its histone-binding affinity. Together, our results provide evidence for regulation of SSRP1 by homodimerization and suggest a potential role for homodimerization in facilitating SPT16-independent functions of SSRP1.
Original languageEnglish
Pages (from-to)10071-10083
Number of pages13
JournalJournal of Biological Chemistry
Volume293
Issue number26
DOIs
Publication statusPublished - 29 Jun 2018

Keywords

  • analytical ultracentrifugation
  • small-angle X-ray scattering (SAXS)
  • histone chaperone
  • oligomerization
  • histone
  • H2A-H2B
  • H3-H4
  • homodimer
  • SSRP1
  • SMALL-ANGLE SCATTERING
  • DNA-POLYMERASE ALPHA
  • N-TERMINAL DOMAIN
  • CHAPERONE FACT
  • SACCHAROMYCES-CEREVISIAE
  • TRANSCRIPTIONAL ACTIVATION
  • NUCLEOSOME REORGANIZATION
  • CHROMATIN
  • REPLICATION
  • SPT16

Cite this