Structural and Biochemical Investigation of Plant‐Nematode Interactions

Abstract

Chorismate, the branch point metabolite in aromatic amino acid biosynthesis, is synthesized by plants, bacteria, and fungi. In plants, the three aromatic amino acids, phenylalanine, tyrosine, and tryptophan produce several compounds such as plant growth hormone indole‐3‐acetic‐acid (IAA) and the defense compound salicylic acid (SA). Several plant parasitic nematodes, such as Meloidogyne javanica and Heterodera schachtii secrete chorismate mutase (MjCM and HsCM, respectively), an enzyme that converts chorismate to prephenate, during early stages of infection. The secretion of chorismate mutase competes with the plant for chorismate, reducing IAA and SA, and inhibiting the vascularization and formation of roots. A recently discovered Arabidopsis thaliana (thale cress) protein, GH3.7, is capable of conjugating chorismate to cysteine, and may play an important role during nematode infections. Here, we found that wild‐type and gh3.7 plants infected with the pathogenic bacterium Pseudomonas syringae pv. tomato do not show a significant difference in pathogenic susceptibility. Steady‐state kinetic assays determined that the turnover rate and catalytic efficiency of MjCM and HsCM is significantly reduced compared to the chorismate mutases in Arabidopsis thaliana. MjCM and HsCM structural models were generated through computation modeling and most closely resembled Mycobacterium tuberculosis chorismate mutase. The kinetic and structural characterization of nematode chorismate mutase will provide an insight into the molecular machinery used by plants to ward off parasitic infections.Support or Funding InformationThis work was funded by the National Science Foundation and supported by the Howard Hughes Medical Institute.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.