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Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 3/26/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Trichothecenes are sesquiterpenoid toxins produced by several Fusarium species. The importance of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) in the regulation of trichothecene production was investigated in G. pulicaris R-6380. A portion of the gene encoding HMGR (Ipr1) was isolated from G. pulicaris R-6380 and its nucleotide sequence determined. The gene fragment specifies the C-terminal 340 amino acids of HMGR representing the highly conserved catalytic domain of this enzyme. The G. pulicaris sequence is 76% homologous with the corresponding region of HMGR from S. cerevisiae. The Ipr1 gene is present in a single copy and hybridizes to an mRNA of 3.1 Kb. Transcription of Ipr1 in G. pulicaris was analyzed in both the wild- type strain R-6380 and the mutant strain BC51 (Tri5-) which is blocked in the first step of the trichothecene pathway. Under growth conditions that support trichothecene production mRNA levels increased 3-fold in R-6380 cultures and 6 to 7-fold in BC51 cultures over a time period of 18 h. The levels of HMGR activity were also observed to increase 2 to 3-fold in R-6380 and 5 to 6-fold in BC51. The results suggest that increases in both Ipr1 expression and HMGR activity are closely correlated with trichothecene biosynthesis in G. pulicaris, and that the observed increases in HMGR activity do not require the presence of a functional trichothecene pathway. |
