Biogenesis of a respiratory complex is orchestrated by a single accessory protein.
The biogenesis of respiratory complexes is a multistep process that requires finely tuned coordination of subunit assembly, metal cofactor insertion, and membrane-anchoring events. The dissimilatory nitrate reductase of the bacterial anaerobic respiratory chain is a membrane-bound heterotrimeric complex nitrate reductase A (NarGHI) carrying no less than eight redox centers. Here, we identified different stable folding assembly intermediates of the nitrate reductase complex and analyzed their redox cofactor contents using electron paramagnetic resonance spectroscopy. Upon the absence of the accessory protein NarJ, a global defect in metal incorporation was revealed. In addition to the molybdenum cofactor, we show that NarJ is required for specific insertion of the proximal iron-sulfur cluster (FS0) within the soluble nitrate reductase (NarGH) catalytic dimer. Further, we establish that NarJ ensures complete maturation of the b-type cytochrome subunit NarI by a proper timing for membrane anchoring of the NarGH complex. Our findings demonstrate that NarJ has a multifunctional role by orchestrating both the maturation and the assembly steps.
Lanciano
Pascal
P
Laboratoire de Chimie Bactérienne, Institut de Biologie Structurale et Microbiologie, CNRS, Université de Provence (Aix-Marseille I), Marseille cedex 09, France.
Vergnes
Alexandra
A
Grimaldi
Stéphane
S
Guigliarelli
Bruno
B
Magalon
Axel
A
D000693:Anaerobiosis; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes; D050901:Nitrate Reductase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; C508364:NarJ protein, E coli; D021122:Protein Subunits; D050901:Nitrate Reductase; C494404:napA protein, E coli