MATβV2 C-terminal interactions with MATα2. (a) Each MATβV2 subunit interacts with the core by inserting its C-terminus (green) in a tunnel created at the interface between two MATα2 subunits (slate, red). The residues involved in the interaction are in stick representation (hydrogen bonds in black dotted lines). (b) Superposition of MATβ (PDB entry 2ydy
) in blue with MATβV2 from the complex with MATα2 (green). The black arrow indicates the conformational change of the unfolded C-terminal loop. (c) Gel-filtration profiles for MAT(α2)4(βV2)2 (red), MAT(α2)4(βV1)2 (dark green) and MAT(α2)4 (blue). For complex formation MATα2 was incubated with both MATβ variants prior to being loaded onto a Superdex 200 10/300 column. The gel-filtration profiles clearly show the shift of the peak that contains the complex (top) and absence of complex formation when MATβV2ΔW309 (black) is used; MAT(α2)4 (blue) and MATβV2ΔW309 (light green) were loaded as controls (bottom). (d) ITC of MATα2 with MATβV2; the top graphs represent the differential heat released during the titration of MATβV2ΔW309 or MATβV2 with MATα2. The bottom graphs represent the fitted binding isotherms. (e) As in (d) ITC of MATα2 with MATβV1ΔW320 or MATβV1.