title: The P34 syringolide elicitor receptor interacts with a soybean photorespiration enzyme, NADH-dependent hydroxypyruvate reductase.
abstract: The syringolide receptor P34 mediates avrD-Rpg4 gene-for-gene complementarity in soybean. However, the mechanism underlying P34 signal transmission after syringolide binding is unknown. In an effort to identify a second messenger for P34, soybean leaf proteins were run though a P34-affinity column. A 42-kDa protein which specifically bound to the column was identified as a putative plant NADH-dependent hydroxypyruvate reductase (HPR) by N-terminal peptide sequencing. HPR is an important enzyme involved in the plant photorespiration system. Screening of a soybean cDNA library yielded two distinct HPR clones that encoded proteins with 97% identity (P42-1 and P42-2). Surprisingly, only P42-2 displayed good binding with P34 in a yeast two-hybrid assay, indicating that P42-2, but not P42-1, is a potential second messenger for P34. Glycerate and its analogs, which are utilized in the photorespiration system, were tested for their inhibitory effect on syringolide-induced hypersensitive response (HR) to evaluate the biological significance of P42-2. Interestingly, the downstream products of HPR (glycerate and 3-phosphoglycerate) inhibited HR but the upstream compounds (hydroxypyruvate or serine) did not have a significant effect on HR. These results suggest that P42-2 is a primary target for a P34/syringolide complex and that P42-2 binding with the complex probably induces HR by inhibiting one or more HPR functions in soybean.
authors.affiliation: Department of Plant Pathology and Center for Plant Cell Biology, University of California, Riverside 92521 USA. okinakayas@aol.com
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Okinaka
authors.forename: Ching-Hong
authors.initials: CH
authors.lastname: Yang
authors.forename: Eliot
authors.initials: E
authors.lastname: Herman
authors.forename: Anthony
authors.initials: A
authors.lastname: Kinney
authors.forename: Noel T
authors.initials: NT
authors.lastname: Keen
mesh_terms: D000485:Allergens; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001665:Binding Sites / Q000235:genetics; D002237:Carbohydrate Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D008027:Light; D008969:Molecular Sequence Data; D010101:Oxygen Consumption / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D030262:Soybean Proteins; D013025:Glycine max / Q000201:enzymology / Q000235:genetics*; D020798:Two-Hybrid System Techniques
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D018076:DNA, Complementary; D010940:Plant Proteins; D030262:Soybean Proteins; C075135:P34 protein, Glycine max; D002237:Carbohydrate Dehydrogenases; C020669:Glycerate dehydrogenase