Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2015
Publication Date: 8/1/2015
Citation: Gao, M., Glenn, A.E., Gold, S.E. 2015. Molecular Exploration of Beta-Lactamases in Fusarium verticillioides. American Phytopathological Society Annual Meeting. August 1-5, 2015. Pasadena, CA.
Interpretive Summary: Bacterial beta-lactamases are well studied in bacterial systems where they play important roles in antibiotic resistance. In contrast, almost nothing is known about proteins with similar motifs in fungi. In the mycotoxigenic fungus Fusarium verticillioides there are 46 such related lactamase genes. We hypothesize that most of these likely are involved in breakdown of anti-fungal compounds. We are exploring their roles in response to specific lactam compounds with the initial focus on one produced by another fungus named Acremonium zeae that, like F. verticillioides, inhabits maize seed.
Technical Abstract: The mycotoxigenic fungus Fusarium verticillioides (Fv) is one of the most prevalent maize fungal pathogens. Fv mycotoxins are a significant food safety issue and have given rise to exposure concerns worldwide. The FDB1 locus, a beta-lactamase-containing Fv gene cluster, was previously shown to be induced by and responsible for the breakdown of and resistance to the maize benzoxazolinones phytoanticipins. Examination of the Fv genome indicates a large expansion of genes with beta-lactamase domains. Of 46 identified Fv lactamase domain containing proteins, 38 were predicted to be associated with lactam hydrolysis and fall into two families, the metallo-beta-lactamases and cephalosporinases. We hypothesize that many of these beta-lactamases contribute to tolerance to additional unidentified lactam xenobiotics. Based on the results at the FDB1 locus, in order to better understand the function of beta-lactamase genes and their putative clusters, we will assess the induction of particular subsets of beta-lactamase genes upon exposure to select lactams. Mutants in induced beta-lactamase genes will be tested for altered sensitivity to the gene inducing lactams. Amongst our current lactam collection we will initially focus on pyrrocidine A, isolated from Acremonium zeae, a coinhabitant of maize seed with Fv. We will present current results on bioinformatic analysis of the Fv beta-lactamase gene family and on global gene expression in response to specific lactam molecules.