Structural basis of the bacteriophage TP901-1 CI repressor dimerization and interaction with DNA

Kim Rasmussen (1) , Anders Varming (1) , Simon Schmidt (1) , Kristian Frandsen (1) , Peter Thulstrup (1) , Malene Ringkjøbing Jensen (2) , Leila Lo Leggio (1)

1 Department of Chemistry [Copenhagen]
2 IBS - UMR 5075 - Institut de biologie structurale

Temperate bacteriophages are known for their bistability, which in TP901-1 is controlled by two proteins, CI and MOR. Clear 1 repressor (CI) is hexameric and binds three palindromic operator sites via an N-terminal helix-turn-helix domain (NTD). A dimeric form, such as the truncated CI∆58 investigated here, is necessary for high-affinity binding to DNA. The crystal structure of the dimerization region (CTD1 ) is determined here, showing that it forms a pair of helical hooks. This newly determined structure is used together with the known crystal structure of the CI-NTD and small angle X-ray scattering data, to determine the solution structure of CI∆58 in complex with a palindromic operator site, showing that the two NTDs bind on opposing sides of the DNA helix.

Mots clés: dimerization domain; helical hook motif; phage repressor; protein-DNA complex; transcription factor

Domaines: Biologie structurale [q-bio.BM]

Kim Rasmussen, Anders Varming, Simon Schmidt, Kristian Frandsen, Peter Thulstrup, et al.. Structural basis of the bacteriophage TP901-1 CI repressor dimerization and interaction with DNA. FEBS Letters, 2018, 592 (10), pp.1738-1750. ⟨10.1002/1873-3468.13060⟩. ⟨hal-01995906⟩