1i1s

SOLUTION STRUCTURE OF THE TRANSCRIPTIONAL ACTIVATION DOMAIN OF THE BACTERIOPHAGE T4 PROTEIN MOTASOLUTION STRUCTURE OF THE TRANSCRIPTIONAL ACTIVATION DOMAIN OF THE BACTERIOPHAGE T4 PROTEIN MOTA

Structural highlights 1i1s is a 1 chain structure with sequence from Escherichia virus T4. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MOTA_BPT4 Required for the transcriptional activation of middle promoters. Middle promoters are characterized by the presence of the conserved sequence [AT]3TGCTTNA (MotA box). MotA binds directly to MotA boxes. Publication Abstract from PubMed Bacteriophage T4 encodes a transcription factor, MotA, that binds to the -30 region of middle-mode promoters and activates transcription by host RNA polymerase. The crystal structure of the N-terminal domain of MotA (MotNF) revealed a six-helix domain in which the two C-terminal alpha-helices mediate the formation of a dimer via a coiled-coil motif and hydrophobic interactions. This structure suggested that full-length MotA binds DNA as a dimer, but subsequent biochemical results have shown that a monomeric form of MotA binds DNA. In this study, gel filtration chromatography, dynamic light scattering, and NMR-based diffusion measurements show conclusively that MotNF is a monomer, and not a dimer, in solution. In addition, we have determined the monomeric solution structure of MotNF using NMR spectroscopy, and have compared this with the dimer structure observed in crystals. The core of the protein assumes the same helical conformation in solution and in crystals, but important differences are observed at the extreme C-terminus. In solution, helix alpha5 is followed by five disordered residues that probably link the N-terminal and C-terminal domains of MotA. In crystals, helix alpha5 forms the dimer interface and is followed by a short sixth helix that further stabilizes the dimer configuration. The solution structure of MotNF supports the conclusion that MotA functions as a monomer, and suggests that the existence of the sixth helix in crystals is a consequence of crystal packing. Our work highlights the importance of investigating protein structures in both crystals and solution to fully understand biomolecular structure and to accurately deduce relationships between structure and function. Solution structure of the transcriptional activation domain of the bacteriophage T4 protein, MotA.,Li N, Zhang W, White SW, Kriwacki RW Biochemistry. 2001 Apr 10;40(14):4293-302. PMID:11284685 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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