Biosynthesis of the 2-Pyridone Tenellin in the Insect Pathogenic FungusBeauveria bassiana (original) (raw)
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Tetrahedron, 1998
AbsWact.-The acyltetramic acid 6 previously proposed as a putative intermediate in tenellin biosynthesis in Beauveria bass/ana has been synthesised in two isotopically labelled forms. This compound was not incorporated into tenellin and was not identifiable in extracts of B. bass/ann and is unlikely to be involved in teneUin biosynthesis. On the other hand a re-evaluation of the role of tFrosine reveals that it is a good precursor to tenellin and is probably generated in vivo by the action of a phenylal=Lnine hydroxyluse directly from L-pbenylalanine. Thus the long held contention that acylteLramic acid 6 und=rgoos oxidative ring expansion to a pyridone no longer appears a valid hypothesis for tenellin biosynthesis.
Synthesis of beauvericin by a multifunctional enzyme
The Journal of Antibiotics, 1988
Beauvericin synthetase, a multifunctional enzyme catalyzing depsipeptide formation in Beauveria bassiana was purified to near homogeneity. The enzymeconsists of a single polypeptide chain with a molecular mass of about 250 kdaltons. The mechanismof beauvericin formation is very similar to that of the cyclohexadepsipeptide enniatin.
Chemistry & Biology, 2008
Beauvericin, a cyclohexadepsipeptide ionophore from the entomopathogen Beauveria bassiana, shows antibiotic, antifungal, insecticidal, and cancer cell antiproliferative and antihaptotactic (cell motility inhibitory) activity in vitro. The bbBeas gene encoding the BbBEAS nonribosomal peptide synthetase was isolated from B. bassiana and confirmed to be responsible for beauvericin biosynthesis by targeted disruption. BbBEAS utilizes D-2-hydroxyisovalerate (D-Hiv) and L-phenylalanine (Phe) for the iterative synthesis of a predicted N-methyl-dipeptidol intermediate, and forms the cyclic trimeric ester beauvericin from this intermediate in an unusual recursive process. Heterologous expression of the bbBeas gene in Escherichia coli to produce the 3189 amino acid, 351.9 kDa BbBEAS enzyme provided a strain proficient in beauvericin biosynthesis. Comparative infection assays with a BbBEAS knockout B. bassiana strain against three insect hosts revealed that beauvericin plays a highly significant but not indispensable role in virulence. 898 Chemistry & Biology 15, 898-907, September 22,
Current Microbiology, 2011
The cyclohexadepsipeptide beauvericin (BEA) is a mycotoxin produced by the fungus Beauveria bassiana (Bals.). Using ELISA, different accessions of B. bassiana, belonging to distinct genetic groups, were analyzed to determine their variability in BEA production. The cytotoxic effect of pure mycotoxins and crude extracts was also tested on insect cell lines SF-9 and SF-21. The results showed that BEA production was significantly different between all strains. Bb 9024 exhibited the highest levels (98.56 mg/l), while Bb 9001 the lowest (15.66 mg/l). Statistical difference was found when BEA CC 50 values (2.81 and 6.94 lM) were compared with those values from others mycotoxins (4.23-11.95 lM). Although no correlation has been observed between beauvericin production and phylogenetic grouping, the results suggest a comprehensible involvement of these metabolites during the infection process. The biological evaluation of metabolites produce by entomopathogenic fungi provides better criteria to design more effective formulations for pest management.
J. Nat. Prod, 2003
A limited number of insect pathogenic fungi have been investigated with respect to their secondary metabolite profiles. Pigments such as oosporein, 4 tenellin, and bassianin, 5,6 the cyclic depsipeptides destruxines, 7 beauvericin, bassianolides, and the beauveriolides, 8 and lactams such as ...
Mexican journal of biotechnology
The application of entomopathogenic fungi as biological control agent is an activity that has been carried out for a long time because they can regulate insect pests through specific formulations of spores and blastospores as infective units, as well as their endophytic ability in some plants offers protection against plant pathogens. Due to its wide distribution and antagonistic ability, Beauveria bassiana is widely used all around the world. Among its main mechanisms of infection is the REVIEW ARTICLE
FEMS Microbiology Letters
Iron is an essential element for life. However, the overload of iron can be toxic. Here, we investigated the significant increase of tenellin and iron–tenellin complex production in ferricrocin-deficient mutants of Beauveria bassiana. Our chemical analysis indicated that the ferricrocin-deficient mutants T1, T3 and T5 nearly abolished ferricrocin production. In turn, these mutants had significant accumulation of iron–tenellin complex in their mycelia at 247–289 mg g−1 cell dry weight under iron-replete condition. Both tenellin and iron–tenellin complex were not detected in the wild-type under such condition. Mass analysis of the mutants’ crude extracts demonstrated that tenellin formed a 3:1 complex with iron in the absence of ferricrocin. The unexpected link between ferricrocin and tenellin biosynthesis in ferricrocin-deficient mutants could be a survival strategy during iron-mediated oxidative stress.
Isolation and characterization of 2-pyridone alkaloids and alloxazines from Beauveria bassiana
Natural Product Research, 2016
Two novel compounds bearing heterocyclic nitrogen, 2-pyridone alkaloid (1) and alloxazine derivative (2), along with the known pretenellin B (3), pyridovericin (4) and lumichrome (5) were isolated from a culture of the entomopathogenic fungal strain Beauveria bassiana. The chemical structures of 2-pyridone alkaloid and alloxazine derivative were established on the basis of the interpretation of spectroscopic data. The isolated compounds were evaluated in a panel of five cancer cell lines and pyridovericin exhibited cytotoxicity (IC 50 , μM) against cancer cell lines: HL-60 (25.9 ± 0.3), HCT8 (34.6 ± 3.6), MDA-MB435 (34.8 ± 3.8) and SF295 (31.1 ± 0.6). Considering that other pyridone compounds display good cytotoxic activity, it would be suggested to obtain new semi synthetic derivatives of pyridovericin, for the development of new cytotoxic chemical entities.