Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 12, 2012
Publication Date: March 12, 2013
Citation: Gold, S.E., Lin, X., Crenshaw, N.J., Glenn, A.E. 2013. Family disintegration: one fusarium verticillioides beta-lactamase at a time [abstract]. Fungal Genetics Reports 60(Suppl:Abstract #539. p. 253. Interpretive Summary: Beta-lactamase enzymes are nearly unexplored in fungi. In bacteria they are a major source of antibiotic resistance. In Fusarium verticillioides a rather large number of genes identified as potentially encoding beta-lactamases was discovered after finding that one of these enzymes is important for colonization of the corn plant host. In this report we describe a second beta-lactamase that is required for normal fungal growth. We hypothesize that we have deleted a gene that is required for resistance to an antifungal antibiotic produced by F. verticillioides itself.
Technical Abstract: Fusarium verticillioides is a mycotoxigenic fungus found commonly on maize, where it primarily exhibits asymptomatic endophytic growth. The F. verticillioides genome possesses approximately 30 regions that potentially encode beta-lactamase enzymatic domains. These enzymes are classically involved in bacterial resistance to beta-lactam antibiotics, for example penicillinase. Our attention was drawn to this enzymatic function by the recent finding that the gene FVEG_08291 is essential for resistance to maize phytoanticipins such as 2-benzoxazolinone (BOA), which possesses a gamma-lactam moiety, the presumed enzymatic target (see poster by Glenn et al.). FVEG_08291 belongs to a subset of these enzymes known as metallo-beta-lactamases. Beta-lactamase enzyme function is not well studied in the fungi, so, in order to further evaluate the roles of these enzymes in F. verticillioides, we are in the process of deleting the members of their encoding gene family. We assigned directed-research undergraduates each a specific gene, for which they produced deletion constructs by DelsGate and/or OSCAR methodology and generated fungal transformants for analysis. Deletion mutants in one of the other metallo-beta-lactamase encoding genes (FVEG_12159) showed a dramatic defective growth phenotype. This observation raises the interesting hypothesis that perhaps this mutant is no longer resistant to a lactam moiety containing compound produced by F. verticillioides itself. Data will be presented on initial progress with this project.