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PROSITE documentation PDOC00085Nitrogenases component 1 alpha and beta subunits signatures
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PURL: https://purl.expasy.org/prosite/documentation/PDOC00085
Nitrogenase (EC 1.18.6.1) [1] is the enzyme system responsible for biological nitrogen fixation. Nitrogenase is an oligomeric complex which consists of two components: component 2 is an homodimer of an iron-sulfur protein, while component 1 which contains the active site for the reduction of nitrogen to ammonia exists in three different forms:
- A molybdenum-iron containing protein (MoFe). The MoFe protein is a hetero- tetramer consisting of two pairs of α (nifD) and β (nifK) subunits.
- A vanadium-iron containing protein (VFe). The VFe protein is a hexamer of two pairs each of α (vnfD), β (vnfK), and delta (vnfG) subunits.
- The third form of component 1 seems to only contain iron. Like the vanadium form it is a hexamer composed of α (anfD), β (anfK), and delta (anfG) subunits.
The α and β chains of the three types of component 1 are evolutionary related and they are also related to proteins nifE and nifN, which are most probably involved in the iron-molybdenum cofactor biosynthesis [2].
We selected as signature patterns for this family of proteins two stretches of residues which are located in the N-terminal section and which each contain a conserved cysteine thought to be one of the ligands for the metal-sulfur clusters.
Last update:May 2004 / Text revised.
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PROSITE methods (with tools and information) covered by this documentation:
| 1 | Authors | Pau R.N. |
| Title | Nitrogenases without molybdenum. | |
| Source | Trends Biochem. Sci. 14:183-186(1989). | |
| PubMed ID | 2672439 |
| 2 | Authors | Aguilar O.M. Taormino J. Thony B. Ramseier T. Hennecke H. Szalay A.A. |
| Title | The nifEN genes participating in FeMo cofactor biosynthesis and genes encoding dinitrogenase are part of the same operon in Bradyrhizobium species. | |
| Source | Mol. Gen. Genet. 224:413-420(1990). | |
| PubMed ID | 2266945 |
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