Structural and biochemical characterisation of an iterative GCN5-related N -acetyltransferase required for fungal siderophore tailoring
Year: 2026
Type: preprint
Abstract: ABSTRACT Siderophore-mediated iron acquisition is essential for fungal survival, particularly under iron-limiting conditions. In Aspergillus fumigatus , SidG, a member of the GCN5-related N -acetyltransferase (GNAT) superfamily, catalyses the final step in the biosynthesis of the extracellular siderophore triacetylfusarinine C (TAFC) through sequential acetylation of the precursor fusarinine C (FsC). However, the timing, catalytic mechanism, and functional significance of this modification are not fully understood. Here, we reconstituted SidG activity in vitro and combined native mass spectrometry, X-ray crystallography, molecular dynamics simulations, and site-directed mutagenesis to investigate its catalytic properties. Our analyses demonstrate that SidG selectively binds acetyl-CoA from the cellular milieu and iteratively acetylates the FsC scaffold prior to iron chelation. Structural, biochemical, and molecular dynamics analyses support a direct transfer mechanism, identify key catalytic residues, and demonstrate the strict selectivity of SidG for short-chain acyl-CoA donors. Together, these findings establish the molecular basis for SidG-dependent siderophore tailoring and expand our understanding of GNAT-catalysed transformations in fungal natural product biosynthesis.
Authors: Joseph D. Newman, Y. T. Candace Ho, Christopher D. Fage, Günther Winkelmann, Lona M. Alkhalaf, Józef R. Lewandowski, Fabrizio Alberti, Matthew Jenner
Language: English
Subfield: Applied Microbiology and Biotechnology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
Funders: Joint Programming Initiative on Antimicrobial Resistance, UK Research and Innovation, Research Councils UK, University of Warwick, Agence Nationale de la Recherche, Medical Research Council, Engineering and Physical Sciences Research Council, Biotechnology and Biological Sciences Research Council
Awards: Adapting Versatile Opportunities for Glycopeptide Antibiotics against Drug-Resistant Organisms, G1343835162, DTP 2020-2021 University of Warwick, Idex Paris-Saclay, G31693196, Warwick Integrative Synthetic Biology Centre, G4122777843, Pushing the Limits of High-Field Solid-State NMR Technology: Enhancing Applications to Advanced Materials, the Life Sciences and Pharmaceuticals, Production of high-value chemicals in the button mushroom: a synthetic biology toolkit, Mechanisms of enoyl reductase recruitment and iterative module suppression in trans-acyltransferase polyketide synthases, G625002215, G6426520074, Dissecting and Harnessing Carrier Protein Interactions in Fungal Megasynth(et)ases, Multidisciplinary toolbox for characterising lipid II binding antibiotics, Elucidating and Exploiting Natural Combinatorial Biosynthesis of Hybrid Polyketide-Nonribosomal Peptide Histone Deacetylase Inhibitors, G896679083
OpenAlex ID: W7212714202