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Figure 3
Overview of fragment binding in the ATP-binding site (site 1). (a) A schematic representation of three crystal structures, apo HSP90N, HSP90N–ATP and the binding fragment compound, illustrated in different colors (green for apo, blue for HSP90N–ATP and purple for the binding fragment). (b) A detailed display of hydrogen bonding in apo HSP90N reveals hydrogen bonds between Glu25 and Lys112, as well as between Gln23 and Asn106. (c) An analysis of the HSP90N–ATP interaction shows that new hydrogen bonds are formed directly between Thr184 and Asp93 and ATP. Additionally, Lys112 forms two new hydrogen bonds to ATP, mediated by two water molecules. (d) A detailed interaction analysis between fragment 10T-0263 and HSP90N indicates π–π stacking between the benzene ring of the fragment and the benzene ring of Phe138. There is a direct hydrogen-bonding interaction between the fragment and Trp162 and Asp93, along with water-mediated hydrogen bonding to Leu103, Thr184 and Gly97. Hydrogen bonds are represented as black dashed lines, while small red dots denote water molecules.

IUCrJ
Volume 12| Part 2| March 2025|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252524012247