Crystal structure of diaphorin methanol monosolvaate isolated from diaphorina citri kuwayama, the insect vector of citrus greening disease

Authors: SZEBENYI, D. MARIAN - Cornell University; KRIKSUNOV, IRINIA - Cornell University; Howe, Kevin; Ramsey, John - John; Hall, David; Heck, Michelle; Krasnoff, Stuart

Submitted to: Acta Crystallographica Secion E
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2018
Publication Date: 3/2/2018
Citation: Szebenyi, D., Kriksunov, I., Howe, K.J., Ramsey, J.S., Hall, D.G., Heck, M.L., Krasnoff, S. 2018. Crystal structure of diaphorin methanol monosolvaate isolated from diaphorina citri kuwayama, the insect vector of citrus greening disease. Acta Crystallographica Secion E. 74(Pt 4):445-449. https://doi.org/10.1107/S2056989018002992.
DOI: https://doi.org/10.1107/S2056989018002992

Interpretive Summary: The three-dimensional structure of diaphorin, a small molecule produced by the Asian citrus psyllid, was solved using X-ray crystallography. The psyllid is the insect vector responsible for spreading the pathogen associated with the invasive citrus greening disease. Within the psyllid, diaphorin is produced by a beneficial bacterium housed in a specialized symbiotic organ. The structure of diaphorin is similar to pederin, a small molecule produced by a bacterial partner of the rove beetle. The diaphorin structure revealed important insights into the putative function of diaphorin in the Asian citrus psyllid. Blocking the production or function of diaphorin in the psyllid may be a novel means to specifically manage psyllid populations and citrus greening disease.

Technical Abstract: The title compound C22H39NO9 CH3OH [systematic name: (S)-N-((S)- {(2S,4R,6R)-6-[(S)-2,3-dihydroxypropyl]-4-hydroxy-5,5-dimethyltetrahydro-2H- pyran-2-yl}(hydroxy)methyl)-2-hydroxy-2-[(2R,5R,6R)-2-methoxy-5,6-dimeth- yl-4-methylenetetrahydro-2H-pyran-2-yl]acetamide methanol monosolvate], was isolated from the Asian citrus psyllid, Diaphorina citri Kuwayama, and crystallizes in the space group P21. ‘Candidatus Profftella armatura’ a bacterial endosymbiont of D. citri, biosynthesizes diaphorin, which is a hybrid polyketide– nonribosomal peptide comprising two highly substituted tetrahydropyran rings joined by an N-acyl aminal bridge [Nakabachi et al. (2013). Curr. Biol. 23, 1478– 1484]. The crystal structure of the title compound establishes the complete relative configuration of diaphorin, which agrees at all nine chiral centers with the structure of the methanol monosolvate of the di-p-bromobenzoate derivative of pederin, a biogenically related compound whose crystal structure was reported previously [Furusaki et al. (1968). Tetrahedron Lett. 9, 6301–6304]. Thus, the absolute configuration of diaphorin is proposed by analogy to that of pederin.