Abstract
The cyclic tetrapeptide HC-toxin is required for pathogenicity of the filamentous fungus Cochliobolus carbonum on maize. HC-toxin production is controlled by a complex locus, TOX2. The isolation and characterization of a new gene of the TOX2 locus, TOXF, is reported. It is shown that TOXF is specifically required for HC-toxin production and pathogenicity. It is present as two or three copies in all HC-toxin-producing (Tox2+) isolates and is absent in toxin-non-producing strains. The deduced amino acid sequence of TOXF has moderate homology to many known or putative branched-chain-amino-acid transaminases from various species. A strain of C. carbonum with all copies of TOXF disrupted grew normally but lost HC-toxin production and pathogenicity. It is proposed that TOXF has a biosynthetic role in HC-toxin synthesis, perhaps to aminate a precursor of Aeo (2-amino-9, 10-epoxi-8-oxodecanoic acid).
Original language | English |
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Pages (from-to) | 3539-3546 |
Number of pages | 8 |
Journal | Microbiology |
Volume | 145 |
Issue number | 12 |
DOIs | |
State | Published - Dec 1999 |
Keywords
- Branched-chain-amino-acid transaminase
- Cochliobolus (Helminthosporium) carbonum
- Cyclic peptide
- HC-toxin
- TOXF