Structural and biochemical characterisation of an iterative GCN5-related N-acetyltransferase required for fungal siderophore tailoring
- 1Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
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.
Related
- Structural and immunogenic characterisation of ChAdOx1 Chik-derived Chikungunya VLPs supports a mechanistic rationale for vaccine-induced protection
- Structural characterisation of Burkholderia pseudomallei BPSL0610 reveals its thioesterase features
- Biochemical, structural, and functional characterization of the Nocardia asteroides dihydrofolate reductase: a primary target of anti-nocardiosis treatment
- CREBBP variants underlying Menke-Hennekam syndrome exhibit histone acetyltransferase hyperactivity with divergent phase behaviors
- Targeting N-acetyltransferase 10 reprograms Treg function to enhance anti-PD-1 immunotherapy sensitivity in murine lung tumors.
BibTeX
@misc{newman2026structural,
title = {{Structural and biochemical characterisation of an iterative GCN5-related N-acetyltransferase required for fungal siderophore tailoring}},
author = {J. D. Newman and Y. T. C. Ho and C. D. Fage and G. Winkelmann and L. M. Alkhalaf and J. R. Lewandowski and F. Alberti and M. Jenner},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.24.754016},
url = {https://www.biorxiv.org/content/10.64898/2026.09.24.754016v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Structural and biochemical characterisation of an iterative GCN5-related N-acetyltransferase required for fungal siderophore tailoring
AU - J. D. Newman
AU - Y. T. C. Ho
AU - C. D. Fage
AU - G. Winkelmann
AU - L. M. Alkhalaf
AU - J. R. Lewandowski
AU - F. Alberti
AU - M. Jenner
PY - 2026
DA - 2026/09/24
PB - bioRxiv
DO - 10.64898/2026.09.24.754016
UR - https://www.biorxiv.org/content/10.64898/2026.09.24.754016v1
AB - 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.
ER -