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

Abstract

Three non-ribosomal peptide synthetase genes, termed sidD, sidC and sidE, have been identified in Aspergillus fumigatus. Gene expression analysis by RT-PCR confirms that expression of both sidD and C 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 ( approximately 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.

Targeted Disruption of Nonribosomal Peptide Synthetase pes3 Augments the Virulence of Aspergillus fumigatus

“…Since relatively little is known about the biological role of NRP synthetases in A. fumigatus, a starting point for investigation was to probe pathways in which fungal NRP synthetase involvement has already been demonstrated. Phenotypic analyses eliminated a role for pes3 in siderophore biosynthesis and protection against oxidative stress, despite widely reported roles for A. fumigatus and other fungal NRP synthetases in these processes (36,51,57,58,60). Expression of pes3 was detected at low levels in liquid cultures in our study, in agreement with an earlier study by Cramer et al (16).…”

“…A few A. fumigatus NRP synthetases encoding secreted or intracellularly located peptides have been elucidated to date, mainly facilitated through targeted gene deletion and comparative metabolomic studies. Two NRP synthetases, SidC and SidD, were found to be essential for siderophore biosynthesis in A. fumigatus (58,60). GliP, a bimodular NRP synthetase, was shown to be responsible for gliotoxin biosynthesis (5,15); however, the contribution to organismal virulence remains to be definitely established.…”

Analysis of major intracellular proteins of Aspergillus fumigatus by MALDI mass spectrometry: Identification and characterisation of an elongation factor 1B protein with glutathione transferase activity

“…Yet, it is quite surprising that reliable methods for the extraction of proteins from filamentous fungi did not emerge until the early 2000s. Since then, we, and others, have reported essentially similar strategies for mycelial lysis involving vigorous physical disruption (bead-beating [19], grinding in liquid N 2 [7,20], sonication or the use of French press technology [21]). Despite the availability of efficient approaches to cell wall disruption, it is only recently that a strategy for the identification of intracellular proteins from A. fumigatus has been forthcoming [22].…”

“…More recently, we have undertaken the identification of nonribosomal peptide synthetases in A. fumigatus using a combined proteomic and molecular approach [7]. Along with Candida albicans, A. fumigatus is a significant opportunistic pathogen of immunocompromised individuals, indeed approximately 5% of all hospital based nosocomial deaths are due to Aspergillus infections [8].…”

Genome sequencing and analysis of the versatile cell factory Aspergillus niger CBS 513.88

“…Siderophores are secondary metabolites involved in iron assimilation and storage 43 and protection against oxidative stress. One clear example of a siderophore cluster was identified in the genome (Supplementary Table 19).…”