Fig. 3: CH6 is a conserved MT-binding element.

a Model of the human augmin N-clamp hammerhead region (PDB-7SQK) colored according to conservation score, shown from viewing angles distal and proximal to the coiled-coil (CC) region. Coiled-coil region and HAUS8-NT are indicated. Coloring scheme and conserved residues are indicated. b Augmin N-clamp hammerhead region from human (PDB-7SQK), X. laevis (PDB-8AT3), and AF2 predictions for D. melanogaster and A. thaliana were colored according to charge distribution. View distal to the coiled-coil region (see Supplementary Fig. 5a). c Pelleted fraction from tubulin co-sedimentation assays for wild-type and HAUS6^4A-mut (K84A, R90A, K91A, K98A) human augmin N-clamp variants plotted against tubulin concentration. Shown as mean ± SD with fitted binding curves (see Methods and Table 1), coloring as indicated. Curve of wild-type complex from Fig. 1. Experiments were performed in n = 3 repetitions. d Pelleted fraction from tubulin co-sedimentation assays for wild-type and Dgt6_HAUS6^3A-mut (K82A, R88A, K96A) N-clamp variants from D. melanogaster plotted against tubulin concentration. Shown as mean ± SD with fitted binding curves (see Methods and Table 1), coloring as indicated. Curve of wild-type complex from Fig. 1. Experiments were performed in n = 3 repetitions. e Immunofluorescence images following dsRNA-mediated Dgt6_HAUS6 knockdown in D. melanogaster S2 cells. Cells expressing either Dgt6_HAUS6^wild-type-GFP or Dgt6_HAUS6^3A-mut-GFP constructs were stained for α-tubulin, DAPI, and GFP (Dgt6_HAUS6). Representative sections of images showing metaphase cells from wild-type (left) and 3A-mut (right). Scale bars: 5 µm. Clear localization to spindle MTs is indicated with white arrowheads in case of wild-type (see Supplementary Fig. 6). f Quantification of Dgt6_HAUS6 spindle localization after Dgt6_HAUS6 dsRNA treatment (3 or 4 days, see Supplementary Fig. 6). The intensity values of eight line plots per spindle (GFP vs α-tubulin) were compared using Pearson correlation coefficients (PCC) and PCC values were plotted for WT = 68 cells (purple) and 3A-mut = 75 cells (gray). n = 4 experiments (see Supplementary Fig. 6e). The bars represent mean ± SD, statistical significance is indicated by p-values determined using two-sided Mann–Whitney U test. Source data are provided as a Source Data file.