Research Seminar: The radical SAM protein HemW is a Haem Chaperone

Dr. Martina Jahn, Institute of Microbiology, Technical University of Braunschweig

Tuesday 4th December, 1.00 p.m., Stacey Lecture Theatre 1


Haem transfer has so far been studied only for the formation of cytochrome c type hemoproteins. We identified bacterial HemW as a haem chaperone responsible for the insertion of haem b into respiratory chain enzymes. The [4Fe-4S] cluster of the radical SAM enzyme HemW is required for protein dimerization and haem transfer. A bacterial two-hybrid system screen identified bacterioferritins and subunit NarI of the respiratory nitrate reductase as proteins interacting with HemW, with bacterioferritines serving as haem donors. Haem covalently bound to HemW was actively transferred to a haem-depleted, catalytically inactive nitrate reductase in membrane vesicles, restoring its nitrate-reducing enzyme activity.