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I. Introduction
From the
PDB:
Adenosine triphosphate (ATP) hydrolysis in the nitrogenase complex controls the
cycle of association and dissociation between the electron donor adenosine
triphosphatase (ATPase) (Fe-protein) and its target catalytic protein (MoFe-protein),
driving the reduction of dinitrogen into ammonia. Crystal structures in
different nucleotide states have been determined that identify conformational
changes in the nitrogenase complex during ATP turnover. These structures reveal
distinct and mutually exclusive interaction sites on the MoFe-protein surface
that are selectively populated, depending on the Fe-protein nucleotide state. A
consequence of these different docking geometries is that the distance between
redox cofactors, a critical determinant of the intermolecular electron transfer
rate, is coupled to the nucleotide state. More generally, stabilization of
distinct docking geometries by different nucleotide states, as seen for
nitrogenase, could enable nucleotide hydrolysis to drive the relative motion of
protein partners in molecular motors and other systems r.
For more information see
Biochemistry
Online: Chapter 2C - Understanding Protein Conformation
II. General Structure
Cartoon
Reducatase subuits: accepts electrons from Ferrodoxin, binds ATP, 4Fe-4S F Cluster
- E chain: light blue; - F chain: blue
Nitrogenase subuits - converts N2 to NH3, binds 8Fe-7S P cluster, FeMo M Cluster
- A chain: binds P and M cluster; magenta; - B chain: red
Cartoon with ATP analog in E/F chains (stick) and metal clusters (spacefil)
Reducatase subuits: accepts electrons from Ferrodoxin, binds ATP, 4Fe-4S F Cluster
- E chain: light blue
- F chain: blue