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NifS-Mediated Assembly of [4Fe-4S] Clusters in the N- and C-Terminal Domains of the NifU Scaffold Protein.
- Source :
-
Biochemistry . 10/4/2005, Vol. 44 Issue 39, p12955-12969. 15p. - Publication Year :
- 2005
-
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 U-type N-terminal scaffolding domain and the assembly of [4Fe-4S]2+ clusters in the Nfu-type C-terminal scaffolding domain. Both scaffolding domains of NifU are shown to be competent for in vitro maturation of nitrogenase component proteins, as evidenced by rapid transfer of [4Fe-4S]2+ clusters preassembled on either the N- or C-terminal domains to the apo nitrogenase Fe protein. Mutagenesis studies indicate that a conserved aspartate (Asp37) plays a critical role in mediating cluster transfer. The assembly and transfer of clusters on NifU are compared with results reported for U- and Nfu-type scaffold proteins, and the need for two functional Fe-S cluster scaffolding domains on NifU is discussed. [ABSTRACT FROM AUTHOR]
- Subjects :
- *BIOMOLECULES
*SULFUR
*MUTAGENESIS
*GENETIC mutation
*RADIOGENETICS
*NITROGENASES
Subjects
Details
- Language :
- English
- ISSN :
- 00062960
- Volume :
- 44
- Issue :
- 39
- Database :
- Academic Search Index
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 18530623
- Full Text :
- https://doi.org/10.1021/bi051257i