Figure 2.

Use of SYNZIP domains in the design of catalytically efficient PKSs harboring a split module. (A) Design of a bimodular DEBS derivative comprised of LDD(4), intact (5)M1(2) or a split version thereof, and (3)M2-TE. (B) Model of DEBS M1 with the natural AT-KR linker (top) and the SYNZIP-containing variant (bottom). This model was built based on SAXS analysis of DEBS M3.³² Fusion sites of the SYNZIP domains to either the AT or KR are indicated by blue and pink dots, illustrating the parallel orientation of the heterospecific coiled-coil. An eight-residue flexible Gly-Ser linker is used to connect the SYNZIP domain to the PKS protein (see protein sequence Table S2). (C) Turnover rates of bimodular PKSs employing M1 or a split M1. Except for intact M1, at least two independently purified protein preparations were evaluated (1 or 2): each preparation of the N-terminal part is shown in a separate column, whereas preparations of the C-terminal part are indicated as black and white dots. All initial rate data was obtained at 2 μM enzyme concentration and nonlimiting concentrations of propionyl-CoA, methylmalonyl-CoA, and NADPH. Measurements were performed in triplicate, and the grand mean is indicated.