title: The molybdenum cofactor biosynthesis complex interacts with actin filaments via molybdenum insertase Cnx1 as anchor protein in Arabidopsis thaliana.
abstract: The pterin based molybdenum cofactor (Moco) plays an essential role in almost all organisms. Its biosynthesis is catalysed by six enzymes in a conserved four step reaction pathway. The last three steps are located in the cytoplasm, where a multimeric protein complex is formed to protect the intermediates from degradation. Bimolecular fluorescence complementation was used to test for cytoskeleton association of the Moco biosynthesis enzymes with actin filaments and microtubules using known cytoskeleton associated proteins, thus permitting non-invasive in vivo studies. Coding sequences of binding proteins were cloned via the GATEWAY system. No Moco biosynthesis enzyme showed any interaction with microtubules. However, alone the two domain protein Cnx1 exhibited interaction with actin filaments mediated by both domains with the Cnx1G domain displaying a stronger interaction. Cnx6 showed actin association only if unlabelled Cnx1 was co-expressed in comparable amounts. So Cnx1 is likely to be the anchor protein for the whole biosynthesis complex on actin filaments. A stabilization of the whole Moco biosynthesis complex on the cytoskeleton might be crucial. In addition a micro-compartmentation might either allow a localisation near the mitochondrial ATM3 exporter providing the first Moco intermediate or near one of the three molybdate transporters enabling efficient molybdate incorporation.
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: d.kaufholdt@tu-bs.de.
authors.forename: David
authors.initials: D
authors.lastname: Kaufholdt
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: c.baillie@tu-bs.de.
authors.forename: Christin-Kirsty
authors.initials: CK
authors.lastname: Baillie
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: bikker.rolf@mh-hannover.de.
authors.forename: Rolf
authors.initials: R
authors.lastname: Bikker
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: v.burkart@tu-bs.de.
authors.forename: Valentin
authors.initials: V
authors.lastname: Burkart
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: c.dudek@tu-bs.de.
authors.forename: Christian-Alexander
authors.initials: CA
authors.lastname: Dudek
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: l.von-pein@tu-bs.de.
authors.forename: Linn
authors.initials: L
authors.lastname: von Pein
authors.affiliation: Institut für Zoologie, Spielmannstrasse 7, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: m.rothkegel@tu-bs.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Rothkegel
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: r.mendel@tu-bs.de.
authors.forename: Ralf R
authors.initials: RR
authors.lastname: Mendel
authors.affiliation: Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, D-38106 Braunschweig, Germany. Electronic address: r.haensch@tu-bs.de.
authors.forename: Robert
authors.initials: R
authors.lastname: Hänsch
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D037281:Calnexin / Q000378:metabolism*; D003067:Coenzymes / Q000096:biosynthesis* / Q000378:metabolism; D005822:Genetic Vectors; D008667:Metalloproteins / Q000096:biosynthesis* / Q000378:metabolism; D000090006:Molybdenum Cofactors; D011621:Pteridines / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D037281:Calnexin; D003067:Coenzymes; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; C080351:CNX1 protein, Arabidopsis; C022261:molybdopterin
keywords: Bimolecular fluorescence complementation assay; Cytoskeleton binding proteins; GATEWAY-vectors; Micro-compartmentation; Molybdenum cofactor biosynthesis; Protein–protein interaction