engleski

Analysis of the fumitremorgin gene cluster in a human pathogen, Aspergillus fumigatus.

Aspergillus fumigatus strains have been reported to produce a variety of secondary metabolites, including toxic prenylated alkaloids such as fumitremorgin C, and many putative secondary metabolic gene clusters have been identified in the genome reference strain Af293 following the completion of the genome sequence.A gene ftmA encoding a dimodular non-ribosomal peptide syntetase (NRPS) was found within one of the putative secondary metabolic gene clusters. ftmA was overexpressed in strain Af293 by insertion of multiple copies, and in the naï ve host Aspergillus nidulans, which lacks the equivalent gene cluster, under the control of the alcA promoter.Though neither fumitremorgins nor the dipeptide intermediate brevianamide F, cyclo-L-Trp- L-Pro, could be detected in wild-type strains, brevianamide F accumulated in liquid cultures of both species following increased expression of the NRPS gene.The cyclic dipeptide brevianamide F is the precursor of a variety of prenylated alkaloids, including fumitremorgins A, B, C, tryprostatin B and verruculogen.RT-PCR indicated that some of the genes in this cluster are poorly transcribed in Af293.We have also observed that overexpressing both ftmA and ftmB, a prenyl transferase, under a regulatable promoter alcA in A. fumigatus and in A.nidulans led to the accumulation of tryprostatin B which is the next intermediate in the fumitremorgin pathway.In order to determine the function of other genes in the cluster and to understand why it is poorly expressed in Af293, we have begun analysis of a fumitremorgin producing strain Af6460.

fumitremorgin C; mycotoxin; aspergillus; RT-PCR; gene

Rad je nastao kao produkt suradnje sa Zavodom za molekularnu biologiju i biotehnologiju Sveučičišta u Sheffieldu (suradnja dr. Ivan Kosalec).