 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 2]](kw5082fig2mag.jpg)
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Figure 2
Crystal structures of wild-type ClpB NBD2 in the absence of nucleotide (a) and in complex with ADP (b) and the nonhydrolysable ATP analogue AMPPCP (c). The three structures are highly similar, showing an open and inactive arrangement of the catalytic site, independent of the nucleotide state. Strikingly, the Walker A lysine Lys601 is present in a fully stretched conformation, pointing away from the nucleotide and forming hydrogen bonds with the backbone carbonyl groups of Gly595 and Ser708. This leads to an unfavourable positioning of the catalytically essential residues of the Walker B motif (Asp667 and Glu668) and the sensor 2 motif (Asn709). The sensor 2 residue Arg806 is captured by a crystal contact with the neighbouring NBD2 molecule in both the ADP-bound and AMPPCP-bound forms. In the nucleotide-free state Arg806 interacts with the inorganic phosphate ion bound in the catalytic site. Distances are given in Å. |
![[Figure 2]](kw5082fig2.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
