Table 1.
Data collection and refinement statistics of HMA6N-AA.
Table 2.
Data collection and refinement statistics of HMA8N.
Fig 1.
3D structures of HMA6 and HMA8 N-domains.
A The structure of HMA6N-AA with β-strands shown in blue and α-helices in red. Missing loops are outlined by dashed lines. B The structure of HMA8N; colouring is as in A. C Superimposition of the two structures with HMA6N-AA in red and HMA8N in blue.
Fig 2.
Sequence alignment of PIB-type ATPase N-domains.
Alignment of the region covering the N-domains of HMA1, HMA6 and HMA8 from A. thaliana, CopA and CopB from A. fulgidus, CopA from L. pneumophila, CopB from S. solfataricus, the human Menkes (ATP7A) and Wilson proteins (ATP7B) and ZntA from S. sonnei. Disordered regions in HMA6 and HMA8 are marked by a red rectangle. The mutated residues in HMA6 are marked in orange. The secondary structures of HMA6 and HMA8 are indicated above and below the alignment, respectively. Multiple sequence alignment was done using MUSCLE (http://www.ebi.ac.uk/Tools/msa/muscle) and visualized using ESPript 3.0 [35].
Fig 3.
Comparison of PIB-type ATPase N-domains of structural homologs.
Superimposition of HMA6N-AA (gray), HMA8N (red), LpCopA (3RFU, green), AfCopA (2B8E, cyan) and AfCopB (3SKX, orange), SsCopB (2IYE, yellow) and the Wilson disease protein (2ARF, blue).
Table 3.
A matrix of sequence identity values among the PIB-type ATPase N-domains compared to HMA (1, 6 and 8) N-domains.
Table 4.
A matrix of RMSD values (in Å) among the N-domains of structural homologs of HMA6N and HMA8N compared in Fig 3 using the CA positions.
Fig 4.
Effect of the double alanine mutant in HMA6N.
Interface of helix 4 from chain A and the symmetry related chain A* with glutamate modelled at position 709 and 710, matching the WT sequence instead of the two alanine, as found in the structure. Helix 4 is shown in orange in the symmetry related side chain marked with an asterisk.
Fig 5.
A Superimposition of the ATP binding site of HMA6N-AA (red), HMA8N (orange), SsCopB (blue, 2YJ4) and AfCopA (light-blue, 3A1D). Conserved residues are shown as sticks, coloured as the corresponding chain and numbered according to their position in HMA6. ATP and ADP of SsCopB and AfCopA are shown as sticks with carbon atoms show in grey, nitrogen atoms in blue, oxygen atoms in red and phosphate atoms in orange. B Structure of HMA6N-AA and C HMA8N, each with the ATP of the SsCopB structure modelled. For the positioning of the nucleotide the N-domains of HMA6N-AA, HMA8N and SsCopB (2YJ4) were superimposed and as the conserved residues are spatially in close proximity a model of HMA6N-AA and HMA8N together with the ATP of SsCopB was generated. Conserved residues important for the binding are shown in sticks and the ATP as spheres. Colouring as in A.