The LYR protein subunit NB4M/NDUFA6 of mitochondrial complex I anchors an acyl carrier protein and is essential for catalytic activity.
Mitochondrial complex I is the largest and most complicated enzyme of the oxidative phosphorylation system. It comprises a number of so-called accessory subunits of largely unknown structure and function. Here we studied subunit NB4M [NDUFA6, LYR motif containing protein 6 (LYRM6)], a member of the LYRM family of proteins. Chromosomal deletion of the corresponding gene in the yeast Yarrowia lipolytica caused concomitant loss of the mitochondrial acyl carrier protein subunit ACPM1 from the enzyme complex and paralyzed ubiquinone reductase activity. Exchanging the LYR motif and an associated conserved phenylalanine by alanines in subunit NB4M also abolished the activity and binding of subunit ACPM1. We show, by single-particle electron microscopy and structural modeling, that subunits NB4M and ACPM1 form a subdomain that protrudes from the peripheral arm in the vicinity of central subunit domains known to be involved in controlling the catalytic activity of complex I.
Institute of Biochemistry II, Structural Bioenergetics Group, Medical School, Goethe University Frankfurt, 60438 Frankfurt, Germany.
Heike
H
Angerer
Michael
M
Radermacher
Michalina
M
Mańkowska
Mirco
M
Steger
Klaus
K
Zwicker
Heinrich
H
Heide
Ilka
I
Wittig
Ulrich
U
Brandt
Volker
V
Zickermann
D000213:Acyl Carrier Protein / Q000378:metabolism*; D055162:Biocatalysis; D004578:Electron Spin Resonance Spectroscopy; D042967:Electron Transport Complex I / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D025062:Yarrowia / Q000378:metabolism
D000213:Acyl Carrier Protein; D005656:Fungal Proteins; D042967:Electron Transport Complex I