5a7l
TP901-1 CI NTD (res 1-80)
Structural highlights
FunctionPublication Abstract from PubMedThe CI repressor from the temperate bacteriophage TP901-1 consists of two folded domains, an N-terminal helix-turn-helix DNA-binding domain (NTD) and a C-terminal oligomerization domain (CTD), which we here suggest to be further divided into CTD1 and CTD2. Full-length CI is a hexameric protein, whereas a truncated version, CI58, forms dimers. We identify the dimerization region of CI58 as CTD1 and determine its secondary structure to be helical both within the context of CI58 and in isolation. To our knowledge this is the first time that a helical dimerization domain has been found in a phage repressor. We also precisely determine the length of the flexible linker connecting the NTD to the CTD. Using electrophoretic mobility shift assays and native mass spectrometry, we show that CI58 interacts with the OL operator site as one dimer bound to both half-sites, and with much higher affinity than the isolated NTD domain thus demonstrating cooperativity between the two DNA binding domains. Finally, using small angle X-ray scattering data and state-of-the-art ensemble selection techniques, we delineate the conformational space sampled by CI58 in solution, and we discuss the possible role that the dynamics play in CI-repressor function. Structural and dynamics studies of a truncated variant of CI repressor from bacteriophage TP901-1.,Rasmussen KK, Frandsen KE, Boeri Erba E, Pedersen M, Varming AK, Hammer K, Kilstrup M, Thulstrup PW, Blackledge M, Jensen MR, Lo Leggio L Sci Rep. 2016 Jul 12;6:29574. doi: 10.1038/srep29574. PMID:27403839[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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