Ablation of the creA regulator results in amino acid toxicity, temperature sensitivity, pleiotropic effects on cellular development and loss of virulence in the filamentous fungus Beauveria bassiana. (7th January 2014)

• Record Type: Journal Article
• Authors: Luo, Zhibing; Qin, Yuqi; Pei, Yan; Keyhani, Nemat O.
• Is Part Of: Environmental microbiology. Volume 16:Number 4(2014:Apr.)
• Page Start: 1122
• Page End: 1136
• Publication Date: 2014-01-07
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12352
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>For most organisms, carbon and nitrogen uptake are essential for growth, development and, where applicable, pathogenesis. The role of the carbon catabolite repressor transcription factor homologue <italic>BbcreA</italic> in the entomopathogenic fungus <italic>B</italic><italic>eauveria bassiana</italic> was investigated. Deletion of <italic>BbcreA</italic> resulted in pleiotropic effects, including nutrient toxicity, leading to a novel cell lytic phenotype. Fungal growth in rich media and minimal media containing select amino acids/peptides was severely compromised, with microscopic examination revealing conidial‐base germ tube degeneration and cell lysis occurring during growth, a phenomenon exacerbated at higher temperatures (32°C). Depending upon nutrient conditions, growth, pigment and aerial mycelium production, sporulation and dimorphic transition to blastospore production were also impaired in the Δ<italic>BbcreA</italic> strain. Although loss of <italic>BbcreA</italic> resulted in de‐repression of secreted protease and lipase, enzymes critical in mediating pathogenesis, insect bioassays indicated severe defects in virulence using both topical and intra‐haemocoel injection assays, with eruption and subsequent sporulation on host cadavers greatly reduced in the mutant. These data suggest that <italic>BbcreA</italic> functions as more than a carbon repressor and plays important roles in nutrient utilization, cell homeostasis and virulence. In particular, <italic>BbcreA</italic> is required for proper assimilation of select amino acids and peptides, including asparagine, arginine and proline.</p> </abstract>