Figure 4.

S114A MATα2 mutant structure. (A) I222 crystal form has closed gating loop (red) with PPNP and ADO in the active site. (B) In P22₁2₁ crystal form, one monomer shows well‐ordered and closed conformation of the gating loop; ADO and PPNP are bound in the active site, while the other subunit shows a ordered, visible gating loop in the open conformation and no ligand in the active site. (C) Close views of S114A mutation site show the omit map contoured around Ala114 and ligands, ADO, and PPNP. (D) Ordered gating loop (residues 113–125) is in open conformation. Fo‐Fc omit maps are contoured at the 3 σ level and colored in green. (E) Structural alignments of an archaeal MAT in open (PDB: http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4L4Q, gray) and closed gating loop (PDB: http://www.rcsb.org/pdb/search/structidSearch.do?structureId=4L7I, cyan) are shown. Gating loop is shown in red ribbon and all active site ligands (SAMe and Pi) are shown as sticks. (F) Structural alignments of human MATα2 in open (PDB: http://www.rcsb.org/pdb/search/structidSearch.do?structureId=6FAJ, gray) and closed gating loop (PDB: http://www.rcsb.org/pdb/search/structidSearch.do?structureId=5A1I, cyan) are illustrated. Gating loop is shown in red ribbon. SAMe and PPNP are shown as stick.