5MGY

The flavinyl transferase ApbE of Pseudomonas stutzeri matures the NosR protein required for nitrous oxide reduction.

(2016) Biochim Biophys Acta 1858: 95-102

• PubMed: 27864152 Search on PubMed
• DOI: https://doi.org/10.1016/j.bbabio.2016.11.008
• Primary Citation of Related Structures:  
  5MGY


• PubMed Abstract: 
  

  The copper-containing enzyme nitrous oxide reductase (N ₂ OR) catalyzes the transformation of nitrous oxide (N ₂ O) to dinitrogen (N ₂ ) in microbial denitrification. Several accessory factors are essential for assembling the two copper sites Cu _A and Cu _Z , and for maintaining the activity. In particular, the deletion of either the transmembrane iron-sulfur flavoprotein NosR or the periplasmic protein NosX, a member of the ApbE family, abolishes N ₂ O respiration. Here we demonstrate through biochemical and structural studies that the ApbE protein from Pseudomonas stutzeri, where the nosX gene is absent, is a monomeric FAD-binding protein that can serve as the flavin donor for NosR maturation via covalent flavinylation of a threonine residue. The flavin transfer reaction proceeds both in vivo and in vitro to generate post-translationally modified NosR with covalently bound FMN. Only FAD can act as substrate and the reaction requires a divalent cation, preferably Mg ²⁺ that was also present in the crystal structure. In addition, the reaction is species-specific to a certain extent.

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Organizational Affiliation: 

Institute for Biochemistry, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.