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Crystal structure of Hop2-Mnd1 and mechanistic insights into its role in meiotic recombination.

Kang HA, Shin HC, Kalantzi AS, Toseland CP, Kim HM, Gruber S, Peraro MD, Oh BH - Nucleic Acids Res. (2015)

Bottom Line: One end of the rod is linked to two juxtaposed winged-helix domains, and the other end is capped by extra α-helices to form a helical bundle-like structure.Deletion analysis shows that the helical bundle-like structure is sufficient for interacting with the Dmc1-ssDNA nucleofilament, and molecular modeling suggests that the curved rod could be accommodated into the helical groove of the nucleofilament.Remarkably, the winged-helix domains are juxtaposed at fixed relative orientation, and their binding to DNA is likely to perturb the base pairing according to molecular simulations.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, KAIST Institute for the Biocentury, Cancer Metastasis Control Center, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.

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Related in: MedlinePlus

Overall structure of Hop2–Mnd1. (A) Two orthogonal views of the heterodimer. The two proteins are organized into an elongated complex with a parallel coiled coil and two WHDs at the N-terminal ends. Domain organizations (boxes) and intermolecular interactions (arrows) derived from the structure are shown schematically. Helical wheels of the three leucine zippers (LZ1, LZ2, LZ3) are shown. Hydrophobic residues at the a and d positions are in red. LZ3 is atypical in that it contains less leucine residues at the d positions. The experimental SAD map (contoured at 1σ) together with the final refined model is shown for the boxed region that contains selenomethione residues. (B) Structure-based sequence alignment of Hop2 and Mnd1. The two segments were aligned by Clustal X, and amino acid positions were adjusted according to the structural superposition of Hop2 and Mnd1. Two proteins exhibit 20% sequence identity. Identical residues are shown in orange and other conserved residues in apricot. Secondary structure elements are shown above (Hop2) and below (Mnd1) the alignment. Boxes indicate the positions a (sky blue) and d (black) in the heptad repeats.
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Figure 1: Overall structure of Hop2–Mnd1. (A) Two orthogonal views of the heterodimer. The two proteins are organized into an elongated complex with a parallel coiled coil and two WHDs at the N-terminal ends. Domain organizations (boxes) and intermolecular interactions (arrows) derived from the structure are shown schematically. Helical wheels of the three leucine zippers (LZ1, LZ2, LZ3) are shown. Hydrophobic residues at the a and d positions are in red. LZ3 is atypical in that it contains less leucine residues at the d positions. The experimental SAD map (contoured at 1σ) together with the final refined model is shown for the boxed region that contains selenomethione residues. (B) Structure-based sequence alignment of Hop2 and Mnd1. The two segments were aligned by Clustal X, and amino acid positions were adjusted according to the structural superposition of Hop2 and Mnd1. Two proteins exhibit 20% sequence identity. Identical residues are shown in orange and other conserved residues in apricot. Secondary structure elements are shown above (Hop2) and below (Mnd1) the alignment. Boxes indicate the positions a (sky blue) and d (black) in the heptad repeats.

Mentions: The heterodimeric complex of full-length G. lamblia Hop2 (231 residues) and Mnd1 (203 residues) was crystallized subsequently. Nearly all the crystals exhibited very high anisotropic mosaicity, which was likely to arise from weak crystal packing interactions and intrinsic flexibility of the Hop2–Mnd1 heterodimer as described below. After extensive crystal screening to collect suitable X-ray data sets, the structure of Hop2–Mnd1 was determined by the single wavelength anomalous dispersion method using a selenomethionine-derivatized crystal (Table 1). A total of 14 methionine positions in the heterodimer facilitated chain tracing. The asymmetric unit of the crystal contained three copies of Hop2–Mnd1. Only one Hop2–Mnd1 heterodimer, referred to as Heterodimer I, exhibited electron densities for nearly the entire length of the molecules. This copy is used for the following structural description (Figure 1A).


Crystal structure of Hop2-Mnd1 and mechanistic insights into its role in meiotic recombination.

Kang HA, Shin HC, Kalantzi AS, Toseland CP, Kim HM, Gruber S, Peraro MD, Oh BH - Nucleic Acids Res. (2015)

Overall structure of Hop2–Mnd1. (A) Two orthogonal views of the heterodimer. The two proteins are organized into an elongated complex with a parallel coiled coil and two WHDs at the N-terminal ends. Domain organizations (boxes) and intermolecular interactions (arrows) derived from the structure are shown schematically. Helical wheels of the three leucine zippers (LZ1, LZ2, LZ3) are shown. Hydrophobic residues at the a and d positions are in red. LZ3 is atypical in that it contains less leucine residues at the d positions. The experimental SAD map (contoured at 1σ) together with the final refined model is shown for the boxed region that contains selenomethione residues. (B) Structure-based sequence alignment of Hop2 and Mnd1. The two segments were aligned by Clustal X, and amino acid positions were adjusted according to the structural superposition of Hop2 and Mnd1. Two proteins exhibit 20% sequence identity. Identical residues are shown in orange and other conserved residues in apricot. Secondary structure elements are shown above (Hop2) and below (Mnd1) the alignment. Boxes indicate the positions a (sky blue) and d (black) in the heptad repeats.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402518&req=5

Figure 1: Overall structure of Hop2–Mnd1. (A) Two orthogonal views of the heterodimer. The two proteins are organized into an elongated complex with a parallel coiled coil and two WHDs at the N-terminal ends. Domain organizations (boxes) and intermolecular interactions (arrows) derived from the structure are shown schematically. Helical wheels of the three leucine zippers (LZ1, LZ2, LZ3) are shown. Hydrophobic residues at the a and d positions are in red. LZ3 is atypical in that it contains less leucine residues at the d positions. The experimental SAD map (contoured at 1σ) together with the final refined model is shown for the boxed region that contains selenomethione residues. (B) Structure-based sequence alignment of Hop2 and Mnd1. The two segments were aligned by Clustal X, and amino acid positions were adjusted according to the structural superposition of Hop2 and Mnd1. Two proteins exhibit 20% sequence identity. Identical residues are shown in orange and other conserved residues in apricot. Secondary structure elements are shown above (Hop2) and below (Mnd1) the alignment. Boxes indicate the positions a (sky blue) and d (black) in the heptad repeats.
Mentions: The heterodimeric complex of full-length G. lamblia Hop2 (231 residues) and Mnd1 (203 residues) was crystallized subsequently. Nearly all the crystals exhibited very high anisotropic mosaicity, which was likely to arise from weak crystal packing interactions and intrinsic flexibility of the Hop2–Mnd1 heterodimer as described below. After extensive crystal screening to collect suitable X-ray data sets, the structure of Hop2–Mnd1 was determined by the single wavelength anomalous dispersion method using a selenomethionine-derivatized crystal (Table 1). A total of 14 methionine positions in the heterodimer facilitated chain tracing. The asymmetric unit of the crystal contained three copies of Hop2–Mnd1. Only one Hop2–Mnd1 heterodimer, referred to as Heterodimer I, exhibited electron densities for nearly the entire length of the molecules. This copy is used for the following structural description (Figure 1A).

Bottom Line: One end of the rod is linked to two juxtaposed winged-helix domains, and the other end is capped by extra α-helices to form a helical bundle-like structure.Deletion analysis shows that the helical bundle-like structure is sufficient for interacting with the Dmc1-ssDNA nucleofilament, and molecular modeling suggests that the curved rod could be accommodated into the helical groove of the nucleofilament.Remarkably, the winged-helix domains are juxtaposed at fixed relative orientation, and their binding to DNA is likely to perturb the base pairing according to molecular simulations.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, KAIST Institute for the Biocentury, Cancer Metastasis Control Center, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.

Show MeSH
Related in: MedlinePlus