Format

Send to

Choose Destination
See comment in PubMed Commons below
J Biochem. 2013 Jul;154(1):51-60. doi: 10.1093/jb/mvt023. Epub 2013 Mar 29.

Structural and mechanistic insights into the electron flow through protein for cytochrome c-tethering copper nitrite reductase.

Author information

1
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.

Abstract

Copper-containing nitrite reductases (CuNiRs), which catalyse the reversible one-electron reduction of nitrite to nitric oxide, are members of a large family of multi-copper enzymes that require an interprotein electron transfer (ET) reaction with redox partner proteins. Here, we show that the naturally fused type of CuNiR tethering a cytochrome c (Cyt c) at the C-terminus folds as a unique trimeric domain-swapped structure and has a self-sufficient electron flow system. The C-terminal Cyt c domain is located at the surface of the type 1 copper (T1Cu) site in the N-terminal CuNiR domain from the adjacent subunit, the heme-to-Cu distance (10.6 Å) of which is comparable to the transient ET complex of normal CuNiR with Cyt c. The structural aspects for the domain-domain interface and the ET kinetics indicate that the Cyt c-CuNiR domain interaction should be highly transient. The further electrochemical analysis of the interprotein ET reaction with a cognate redox partner protein suggested that an electron is directly transferred from the partner to the T1Cu. Structural and mechanistic comparisons of Cyt c-CuNiR with another cupredoxin-tethering CuNiR highlight the behaviours of extra domains on the fusion types of CuNiRs required for ET through proteins.

KEYWORDS:

X-ray crystal structure; copper nitrite reductase; multi-domain protein; protein electron transfer

PMID:
23543476
DOI:
10.1093/jb/mvt023
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Silverchair Information Systems
    Loading ...
    Support Center