Mass spectrometry of iron-sulfur cluster regulatory proteins

Iron-sulfur (FeS) cluster-containing regulatory proteins play key roles in sensing and responding to environmental change. The cluster functions as the sensory module, undergoing reaction that leads to protein conformational changes that enable the signal to be transduced. The [4Fe-4S] cluster containing WhiB-like (Wbl) family of regulators (named after the first discovered WhiB protein) are found in the actinobacteria, a phylum of Gram-positive bacteria that includes Streptomyces and important pathogens such as Mycobacterium tuberculosis. These proteins play key roles in cell development, controlling sporulation in Streptomyces and the transition into dormancy in M. tuberculosis. Recent work suggests that Wbl proteins may function through sensing nitric oxide (NO) and this project is focussed on understanding this reaction.
The principal technique that will be used is native mass spectrometry (MS), which detects intact proteins in their folded states where non-covalent interactions (including protein-metallocofactor) are preserved upon vaporisation/ionisation. Thus, native MS has the potential to observe not only resting states of enzymes/proteins, but also intermediates in which substrates are non-covalently attached. Initial experiments indicate that native MS can provide an unprecedented level of detail about the reactions of iron-sulfur clusters with physiologically relevant small molecule reactants such as nitric oxide.