Figure 6
Native MS spectra of HypC and HypD dissociated from HypCD complexes reveal absence of the + 136 Da modification on HypC in isc mutants but presence of the [4Fe–4S] cluster on HypD. (a) Mass spectrum of the dissociation of the + 12 charged ion species of the HypCD heterodimer into HypC (charge states + 4 through + 6, red spheres) and HypD (charge states + 6 through + 8, green spheres) at a collision energy of 90 V isolated from strain DHP-D transformed with plasmid pT-hypDCStrep as positive control. (b) Zoom in for HypC (charge state + 5), as well as (c) zoom in for HypD (charge state + 7) are shown for isolated complexes from strains transformed with pT-hypDCStrep: DHP-D (“WT”), CP1233 (∆sufA), CP1244 (∆iscU) and CP411 (∆entC-feoB), and HypCC2A dissociated from the HypCC2AHypD complex isolated from strain DHP-D (∆hypD) transformed with pT-hypDC(C2A)Strep. Signals are labeled with the corresponding m/z value in the first zoomed row. Potential modifications are indicated above the colored overlay. Note that a putative methyl thiazolidine modification accounting for the + 26 Da species is not indicated in the Figure.
