6h5l

Publication Abstract from PubMed

The hydroxylamine oxidoreductase/hydrazine dehydrogenase (HAO/HDH) protein family constitutes an important group of octaheme cytochromes c (OCCs). The majority of these proteins form homotrimers, with their subunits being covalently attached to each other via a rare cross-link between the catalytic heme moiety and a conserved tyrosine residue in an adjacent subunit. This covalent cross-link has been proposed to modulate the active-site heme towards oxidative catalysis by distorting the heme plane. In this study, the crystal structure of a stable complex of an HAO homologue (KsHAOr) with its diheme cytochrome c redox partner (KsDH) from the anammox bacterium Kuenenia stuttgartiensis was determined. KsHAOr lacks the tyrosine cross-link and is therefore tuned to reductive catalysis. The molecular model of the KsHAOr-KsDH complex at 2.6 A resolution shows a heterododecameric (alpha6beta6) assembly, which was also shown to be the oligomeric state in solution by analytical ultracentrifugation and multi-angle static light scattering. The 60-heme-containing protein complex reveals a unique extended electron transfer pathway and provides deeper insights into catalysis and electron transfer in reductive OCCs.

A 60-heme reductase complex from an anammox bacterium shows an extended electron transfer pathway.,Dietl A, Maalcke WJ, Ferousi C, Jetten MSM, Kartal B, Barends TRM Acta Crystallogr D Struct Biol. 2019 Mar 1;75(Pt 3):333-341. doi:, 10.1107/S2059798318017473. Epub 2019 Feb 28. PMID:30950404^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.