PMID:21346172

Citation	Tanaka, K, Nguyen, CT, Libault, M, Cheng, J and Stacey, G (2011) Enzymatic activity of the soybean ecto-apyrase GS52 is essential for stimulation of nodulation. Plant Physiol. 155:1988-98
Abstract	Nitrogen is an essential nutrient for plant growth. In the Rhizobium-legume symbiosis, root nodules are the sites of bacterial nitrogen fixation, in which atmospheric nitrogen is converted into a form that plants can utilize. While recent studies suggested an important role for the soybean (Glycine max) ecto-apyrase GS52 in rhizobial root hair infection and root nodule formation, precisely how this protein impacts the nodulation process remains undetermined. In this study, the biochemical characteristics of the GS52 enzyme were investigated. Computer modeling of the GS52 apyrase structure identified key amino acid residues important for catalytic activity, which were subsequently mutagenized. Although the GS52 enzyme exhibited broad substrate specificity, its activity on pyrimidine nucleotides and diphosphate nucleotides was significantly higher than on ATP. This result was corroborated by structural modeling of GS52, which predicted a low specificity for the adenine base within the substrate-binding pocket of the enzyme. The wild-type enzyme and its inactive mutant forms were expressed in soybean roots in order to evaluate the importance of GS52 enzymatic activity for nodulation. The results indicated a clear correlation between GS52 enzymatic activity and nodule number. Altogether, our study indicates that the catalytic activity of the GS52 apyrase, likely acting on extracellular nucleotides, is critical for rhizobial infection and nodulation.
Links	PubMed PMC3091080 Online version:10.1104/pp.110.170910
Keywords	Apyrase/genetics; Apyrase/metabolism; Catalytic Domain; Gene Expression Regulation, Plant; Models, Molecular; Mutagenesis; Nucleotides/metabolism; Plant Proteins/genetics; Plant Proteins/metabolism; Plant Root Nodulation; Plants, Genetically Modified/enzymology; Plants, Genetically Modified/genetics; Plants, Genetically Modified/microbiology; Protein Structure, Tertiary; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Soybeans/enzymology; Soybeans/genetics; Soybeans/microbiology; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
GLYSO:Q9FVC2		GO:0009877: nodulation	ECO:0000315:		P		Figure 4 shows that transgenic plants expressing wild type GS52 have increase nodulation, and those expressing mutant GS52 do not have increased nodulation.	complete CACAO 5592
GLYSO:Q9FVC2		GO:0017110: nucleoside-diphosphatase activity	ECO:0000314:		F		Figure 1D shows that purified GS52 can release phosphate from a variety of nucleoside diphosphates.	complete CACAO 5591
GLYSO:Q9FVC2		GO:0017111: nucleoside-triphosphatase activity	ECO:0000314:		F		Figure 1D shows that purified GS52 can release phosphate from a variety of nucleoside triphosphates.	complete CACAO 5590
GLYSO:Q9FVC2		GO:0043273: CTPase activity	ECO:0000314:		F		Figure 1D shows GS52 has signifiant CTPase activity; it releases phosphate when reacted with CTP.	complete CACAO 5950
GLYSO:Q9FVC2	enables	GO:0017110: nucleoside-diphosphatase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
GLYSO:Q9FVC2	enables	GO:0043273: CTPase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
GLYSO:Q9FVC2	involved_in	GO:0009877: nodulation	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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