Project description:Fusicoccadiene synthase from Phomopsis amygdali (PaFS) catalyzes the first committed step in the biosynthesis of Fusicoccin A, a diterpene glycoside and a a potential therapeutic agent. PaFS contains a C-terminal prenyltransferase domain that generates geranylgeranyl diphosphate (GGPP) and an N-terminal cyclase domain that utilizes GGPP to generate fusicoccadiene, which comprises the complex 5-8-5 tricyclic hydrocarbon skeleton of Fusicoccin A. The C-termimal domain octamerizes to form a central core, with the eight cyclase domains radiating outward via flexible linker segments with variable extended conformations. Crosslinking-mass spectrometry (XL-MS) experiments affirm and reveal inter-domain interactions, showing that compact conformations can be achieved. These studies, complemented by cryo-EM and functional studies, provide a framework for understanding substrate channeling between consecutive catalytic domains.
Project description:BackgroundPhomopsis longicolla T. W. Hobbs (syn. Diaporthe longicolla) is a seed-borne fungus causing Phomopsis seed decay in soybean. This disease is one of the most devastating diseases reducing soybean seed quality worldwide. To facilitate investigation of the genomic basis of pathogenicity and to understand the mechanism of the disease development, the genome of an isolate, MSPL10-6, from Mississippi, USA was sequenced, de novo assembled, and analyzed.ResultsThe genome of MSPL 10-6 was estimated to be approximately 62 Mb in size with an overall G + C content of 48.6%. Of 16,597 predicted genes, 9866 genes (59.45%) had significant matches to genes in the NCBI nr database, while 18.01% of them did not link to any gene ontology classification, and 9.64% of genes did not significantly match any known genes. Analysis of the 1221 putative genes that encoded carbohydrate-activated enzymes (CAZys) indicated that 715 genes belong to three classes of CAZy that have a direct role in degrading plant cell walls. A novel fungal ulvan lyase (PL24; EC 4.2.2.-) was identified. Approximately 12.7% of the P. longicolla genome consists of repetitive elements. A total of 510 potentially horizontally transferred genes were identified. They appeared to originate from 22 other fungi, 26 eubacteria and 5 archaebacteria.ConclusionsThe genome of the P. longicolla isolate MSPL10-6 represented the first reported genome sequence in the fungal Diaporthe-Phomopsis complex causing soybean diseases. The genome contained a number of Pfams not described previously. Information obtained from this study enhances our knowledge about this seed-borne pathogen and will facilitate further research on the genomic basis and pathogenicity mechanism of P. longicolla and aids in development of improved strategies for efficient management of Phomopsis seed decay in soybean.
