NifS-mediated assembly of [4Fe-4S] clusters in the N- and C-terminal domains of the NifU Scaffold protein

Abstract

NifU is a homodimeric modular protein comprising N- and C-terminal domains and a central domain with a redox-active [2Fe-2S]2+,+ cluster. It plays a crucial role as a scaffold protein, for the assembly of the Fe-S clusters required for the maturation of nif-specific Fe-S proteins. In this work, the time course and products of in vitro NifS-mediated iron-sulfur cluster assembly on full-length NifU and truncated forms involving only the N-terminal domain or the central and C-terminal domains have been investigated using UV-vis absorption and Mössbauer spectroscopies, coupled with analytical studies. The results demonstrate sequential assembly of labile [2Fe-2S]2+ and [4Fe-4S]2+ clusters in the..