Dimerization of the plant molybdenum insertase Cnx1E is required for synthesis of the molybdenum cofactor.
The molybdenum cofactor (Moco) is a redox active prosthetic group, essentially required for numerous enzyme-catalyzed two electron transfer reactions. Moco is synthesized by an evolutionarily old and highly conserved multistep pathway. In the last step of Moco biosynthesis, the molybdenum center is inserted into the final Moco precursor adenylated molybdopterin (MPT-AMP). This unique and yet poorly characterized maturation reaction finally yields physiologically active Moco. In the model plant Arabidopsis, the two domain enzyme, Cnx1, is required for Moco formation. Recently, a genetic screen identified novel Arabidopsis cnx1 mutant plant lines each harboring a single amino acid exchange in the N-terminal Cnx1E domain. Biochemical characterization of the respective recombinant Cnx1E variants revealed two different amino acid exchanges (S197F and G175D) that impair Cnx1E dimerization, thus linking Cnx1E oligomerization to Cnx1 functionality. Analysis of the Cnx1E structure identified Cnx1E active site-bound molybdate and magnesium ions, which allowed to fine-map the Cnx1E MPT-AMP-binding site.
Department of Plant Biology, Braunschweig University of Technology, Braunschweig 38106, Germany.|Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
Joern
J
Krausze
Department of Plant Biology, Braunschweig University of Technology, Braunschweig 38106, Germany.
Corinna
C
Probst
Institute for Biophysical Chemistry, Hannover Medical School, Hannover 30625, Germany.
Ute
U
Curth
Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
Joachim
J
Reichelt
Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
Sayantan
S
Saha
Department of Plant Biology, Braunschweig University of Technology, Braunschweig 38106, Germany.
David
D
Schafflick
Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
Dirk W
DW
Heinz
Department of Plant Biology, Braunschweig University of Technology, Braunschweig 38106, Germany.
Ralf R
RR
Mendel
Department of Plant Biology, Braunschweig University of Technology, Braunschweig 38106, Germany t.kruse@tu-bs.de.
Tobias
T
Kruse
D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D037281:Calnexin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D003067:Coenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008667:Metalloproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000090006:Molybdenum Cofactors; D020125:Mutation, Missense; D055503:Protein Multimerization / Q000502:physiology*; D017433:Protein Structure, Secondary; D011621:Pteridines / Q000737:chemistry / Q000378:metabolism
D029681:Arabidopsis Proteins; D037281:Calnexin; D003067:Coenzymes; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; C080351:CNX1 protein, Arabidopsis; C022261:molybdopterin
Mo-insertase; molybdenum cofactor maturation; molybdenum cofactor synthesis