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

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 investigat...

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Bibliographic Details
Published in:FEBS letters 2018-05, Vol.592 (10), p.1738-1750
Main Authors: Rasmussen, Kim K., Varming, Anders K., Schmidt, Simon N., Frandsen, Kristian E. H., Thulstrup, Peter W., Jensen, Malene Ringkjøbing, Lo Leggio, Leila
Format: Article
Language:English
Subjects:
Biochemistry, Molecular Biology
dimerization domain
helical hook motif
Life Sciences
phage repressor
protein–DNA complex
Structural Biology
transcription factor
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Summary: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.
ISSN:0014-5793
1873-3468
DOI:10.1002/1873-3468.13060