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LiAu is alpha-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Li1+ is bonded in a distorted hexagonal planar geometry to six equivalent Au1- atoms. All Li–Au bond lengths are 2.73 Å. Au1- is bonded in a 6-coordinate geometry to six equivalent Li1+ atoms.
LiAu is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Li1+ is bonded in a body-centered cubic geometry to eight equivalent Au1- atoms. All Li–Au bond lengths are 2.72 Å. Au1- is bonded in a body-centered cubic geometry to eight equivalent Li1+ atoms.
LiAu(S2O7)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six SO4 tetrahedra. There are a spread of Li–O bond distances ranging from 2.11–2.26 Å. Au3+ is bonded in a square co-planar geometry to four O2- atoms. All Au–O bond lengths are 2.03 Å. There are two inequivalent S6+ sites. In the first S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent LiO6 octahedra and a cornercorner with one SO4 tetrahedra. The corner-sharing octahedra tilt angles range from 6–42°. There are a spread of S–O bond distances ranging from 1.43–1.64 Å. In the second S6+ site, S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one LiO6 octahedra and a cornercorner with one SO4 tetrahedra. The corner-sharing octahedral tilt angles are 39°. There are a spread of S–O bond distances ranging from 1.43–1.68 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Au3+ and one S6+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Au3+ and one S6+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Li1+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Li1+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two S6+ atoms. In the seventh O2- site, O2- is bonded in a single-bond geometry to one S6+ atom.
Code and WEAKLIB data for Liau et al. 2021 (ApJ Supplement Series)
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The RAS–RAF pathway is one of the most commonly dysregulated in human cancers. Despite decades of study, understanding of the molecular mechanisms underlying dimerization and activation of the kinase RAF remains limited. Recent structures of inactive RAF monomer and active RAF dimer bound to 14-3-3 have revealed the mechanisms by which 14-3-3 stabilizes both RAF conformations via specific phosphoserine residues. Prior to RAF dimerization, the protein phosphatase 1 catalytic subunit (PP1C) must dephosphorylate the N-terminal phosphoserine (NTpS) of RAF to relieve inhibition by 14-3-3, although PP1C in isolation lacks intrinsic substrate selectivity. SHOC2 is as an essential scaffolding protein that engages both PP1C and RAS to dephosphorylate RAF NTpS, but the structure of SHOC2 and the architecture of the presumptive SHOC2–PP1C–RAS complex remain unknown. Here we present a cryo-electron microscopy structure of the SHOC2–PP1C–MRAS complex to an overall resolution of 3Å, revealing a tripartite molecular architecture in which a crescent-shaped SHOC2 acts as a cradle and brings together PP1C and MRAS. Our work demonstrates the GTP dependence of multiple RAS isoforms for complex formation, delineates the RAS-isoform preference for complex assembly, and uncovers how the SHOC2 scaffold and RAS collectively drive specificity of PP1C for RAF NTpS. Our data indicate that disease-relevant mutations affect complex assembly, reveal the simultaneous requirement of two RAS molecules for RAF activation, and establish rational avenues for discovery of new classes of inhibitors to target this pathway.