Fig 1.
Organization of syneptonemal complex and schematic view of domain organization of SYCP1.
(A) The cartoon of the structure of syneptonemal complex. (B) Schematic view of the domain boundary of SYCP1. The construct used for this structural study is magnified. (C) Size-exclusion chromatography profile. SDS-PAGE loaded fractions (black-bar) of Size-exclusionchromatography are shown under the profile. V.V.: Void volume, C.V.: Column volume, M: Marker, B:Sample just before loaded onto size-exclusion chromatography, F: Fractions loaded onto SDS-PAGE (D) Multi-angle light scattering (MALS) results. The red line indicates the experimental molecular weight. (E) Constructs that have been used for expression and purification of SYCP1.
Table 1.
Data collection and refinement statistics.
Fig 2.
Crystal structure of the SYCP1 CC.
(A) Cartoon figure of monomeric SYCP1 CC structure. The chain from the N- to C-termini is colored blue to red. (B) The dimeric structure of the SYCP1 CC detected at the crystallographic asymmetric unit. (C) Superimposition of chain A and chain B. Structurally different regions are indicated by red-dotted squares. (D) B factor distributions are shown by cartoon. Warm and cold colors indicate high and low B-factor levels, respectively. (E) Electrostatic surface representation of SYCP1 CC.
Fig 3.
Sequence alignment of SYCP1 CC from different species.
The range of solved structures in this study is shown above the sequences. Conserved residues are highlighted with yellow color. Charged and hydrophobic residues that are involved in the interface interaction are shown in blue and red colors, respectively. Red stars indicate mutations that disrupt dimer formations. Heptad repeats are shown below the sequences.
Fig 4.
The details of dimeric interfaces of the SYCP1 CC structure.
(A) Interhelical interactions of coiled coil within the asymmetric unit of the seleno-methionine crystal are shown. The residues in the positions a and d of heptad repeats are presented as a stick model at the top panel. Close-up views of three different parts are shown. The amino acid residues that participated in the interhelical interactions are labelled. L; Left, M; Middle, R; Right. (B) Helical wheel presentation of the heptad repeats in SYCP1 CC. Interhelical charged interactions are indicated by a red-line connecting paired residues. Charged residues and hydrophobic residues are colored blue and red, respectively.
Fig 5.
Disruption of the antiparallel left-handed SYCP1 CC.
(A) Expected critical residues for formation of the antiparallel left-handed SYCP1 CC based on the structure. The 2Fo-Fc simulated annealing omit map (2.0 Å, 1.2 σ) around the critical residues was calculated with the omission of the model. The red dots lines indicate salt bridges and the black dot lines indicate hydrogen bonds. (B) Gel-filtration profiles of wildtype and double mutant (D700R, K764E). (C) Multi angle light scattering (MALS) with selected peak positions of double mutant (D700R, K764E). The red line indicates the experimental molecular weight. (D) Circular dichroic spectra of wildtype and double mutant (D700R, K764E).
Fig 6.
Evidence of antiparallel left-handed SYCP1 CC in solution.
Size-exclusion chromatography profile of GST-fused SYCP1 CC. SDS-PAGE loaded fractions (black-bar) of Size-exclusion chromatography are shown next to the profile. V.V.: Void volume, C.V.: Column volume, M: Marker, B:Sample just before loaded onto size-exclusion chromatography, F: Fractions loaded onto SDS-PAGE, 1: Dimer of GST-fused SYCP1 CC position, 2: Tetramer position, 3: higher oligomer position. Cartoons of oligomeric states of GST-fused SYCP1 CC are shown.
Fig 7.
Putative model of synaptonemal complex based on the current structure of non-canonical anti-parallel coild-coil structure of SYCP1.