1ahd | pdb_00001ahd
DETERMINATION OF THE NMR SOLUTION STRUCTURE OF AN ANTENNAPEDIA HOMEODOMAIN-DNA COMPLEX
Structural highlights
Function[ANTP_DROSU] Sequence-specific transcription factor which is part of a developmental regulatory system that regulates segmental identity in the mesothorax. Provides cells with specific positional identities on the anterior-posterior axis (By similarity).[UniProtKB:P02833] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe nuclear magnetic resonance (NMR) solution structure of a complex formed by the mutant Antennapedia homeodomain with Cys39 replaced by Ser, Antp(C39S), and a 14 base-pair DNA duplex containing the BS2 operator sequence was determined using uniform 13C and 15N-labeling of the protein. Two-dimensional nuclear Overhauser enhancement spectroscopy ([1H,1H]NOESY) with 15N(omega 2)-half-filter and 13C(omega 1, omega 2)-double-half-filter, and three-dimensional heteronuclear-correlated [1H,1H]NOESY yielded a total of 855 intramolecular NOE upper distance constraints in the homeodomain, 151 upper distance constraints within the DNA duplex, and 39 intermolecular protein-DNA upper distance constraints. These data were used as the input for the structure calculation with simulated annealing followed by molecular dynamics in a water bath and energy refinement. A group of 16 conformers was thus generated which represent the solution structure of the Antp(C39S) homeodomain-DNA complex. The new structure determination confirms the salient features reported previously from a preliminary investigation of the same complex, in particular the location of the recognition helix in the major groove with the turn of the helix-turn-helix motif outside the contact area with the DNA, and the N-terminal arm of the homeodomain contacting the minor groove of the DNA. In addition, distinct amino acid side-chain-DNA contacts could be identified, and evidence was found that the invariant residue Asn51 (and possibly also Gln50) is in a slow dynamic equilibrium between two or several different DNA contact sites. The molecular dynamics calculations in a water bath yielded structures with hydration water molecules in the protein-DNA interface, which coincides with direct NMR observations of hydration waters. In the Appendix the experimental data obtained with the Antp(C39S) homeodomain-DNA complex and the techniques used for the structure calculation are evaluated using a simulated input data set derived from the X-ray crystal structure of a DNA complex with a homologous homeodomain. This study indicates that a nearly complete set of NOE upper distance constraints for the Antp(C39S) homeodomain and the protein-DNA interface was presently obtained. It further shows that the structure calculation used here yields a precise reproduction of the crystal structure from the simulated input data, and also results in hydration of the protein-DNA interface in the recalculated complex. Determination of the nuclear magnetic resonance solution structure of an Antennapedia homeodomain-DNA complex.,Billeter M, Qian YQ, Otting G, Muller M, Gehring W, Wuthrich K J Mol Biol. 1993 Dec 20;234(4):1084-93. PMID:7903398[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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