The expression of selected non-ribosomal peptide synthetases inAspergillus fumigatusis controlled by the availability of free iron

Abstract

Three non-ribosomal peptide synthetase genes, termedsidD, sidC andsidE, have been identified inAspergillus fumigatus. Gene expression analysis by RT-PCR confirms that expression of bothsidD andC was reduced by up to 90% under iron-replete conditions indicative of a likely role in siderophore biosynthesis.SidE expression was less sensitive to iron levels. In addition, two proteins purified from mycelia grown under iron-limiting conditions corresponded to SidD (200 kDa) and SidC (496 kDa) as determined by MALDI ToF peptide mass fingerprinting and MALDI LIFT-ToF/ToF. Siderophore synthetases are unique in bacteria and fungi and represent an attractive target for antimicrobial chemotherapy.