PMID:23630326

Citation	Kaufholdt, D, Gehl, C, Geisler, M, Jeske, O, Voedisch, S, Ratke, C, Bollhöner, B, Mendel, RR and Hänsch, R (2013) Visualization and quantification of protein interactions in the biosynthetic pathway of molybdenum cofactor in Arabidopsis thaliana. J. Exp. Bot. 64:2005-16
Abstract	The molybdenum cofactor (Moco) is the active compound at the catalytic site of molybdenum enzymes. Moco is synthesized by a conserved four-step pathway involving six proteins in Arabidopsis thaliana. Bimolecular fluorescence complementation was used to study the subcellular localization and interaction of those proteins catalysing Moco biosynthesis. In addition, the independent split-luciferase approach permitted quantification of the strength of these protein-protein interactions in vivo. Moco biosynthesis starts in mitochondria where two proteins undergo tight interaction. All subsequent steps were found to proceed in the cytosol. Here, the heterotetrameric enzyme molybdopterin synthase (catalysing step two of Moco biosynthesis) and the enzyme molybdenum insertase, which finalizes Moco formation, were found to undergo tight protein interaction as well. This cytosolic multimeric protein complex is dynamic as the small subunits of molybdopterin synthase are known to go on and off in order to become recharged with sulphur. These small subunits undergo a tighter protein contact within the enzyme molybdopterin synthase as compared with their interaction with the sulphurating enzyme. The forces of each of these protein contacts were quantified and provided interaction factors. To confirm the results, in vitro experiments using a technique combining cross-linking and label transfer were conducted. The data presented allowed the outline of the first draft of an interaction matrix for proteins within the pathway of Moco biosynthesis where product-substrate flow is facilitated through micro-compartmentalization in a cytosolic protein complex. The protected sequestering of fragile intermediates and formation of the final product are achieved through a series of direct protein interactions of variable strength.
Links	PubMed PMC3638830 Online version:10.1093/jxb/ert064
Keywords
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:CNX1		GO:0005515: protein binding	ECO:0000021:	UniProtKB:O22827	F		Table 1a and Figure 2a.	complete CACAO 8341
ARATH:MOC2B		GO:0047485: protein N-terminus binding	ECO:0000021:	UniProtKB:Q9S7A3	F		Figure 2I, Table 1a	complete CACAO 8342
ARATH:CNX2		GO:0005739: mitochondrion	ECO:0000314:		C		Figure 4a.	complete CACAO 8343
ARATH:CNX2	part_of	GO:0005739: mitochondrion	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ARATH:CNX3		GO:0005739: mitochondrion	ECO:0000314:		C		Figure 4B.	complete CACAO 8344
ARATH:CNX3	part_of	GO:0005739: mitochondrion	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

See Help:References for how to manage references in GONUTS.