Sammalkorpi, M. | bioRxiv Science

bioRxiv2026

Non-ribosomal Peptides as Structural Determinants of Fungal Hydrophobicity

Fungal surfaces must remain hydrophobic to enable growth, dispersal, and survival under fluctuating environmental conditions, yet the molecular basis of this property remains incompletely understood. Here, we identify fungisporins, fusahexins, and related cyclic non-ribosomal peptides (NRPs) as members of a conserved functional class of fungal metabolites, termed WAter Repellent Peptides (WARPs), that are required for fungal surface hydrophobicity. Across filamentous fungi, WARPs vary substantially in sequence and length but share conserved structural features, including cyclization, hydrophobic amino acid composition, and alternating D- and L-configurations, consistent with a flexible amphiphilic scaffold. Loss of WARP-producing non-ribosomal peptide synthetases results in rapid collapse of aerial hyphae upon water exposure, demonstrating that these peptides are required for maintenance of hydrophobic aerial structures. Using phage-display-derived antibodies, we localize WARPs to the hyphal surface, supporting their role as surface-associated structural components. Together, these findings identify a conserved NRPS-encoded peptide system that contributes to fungal hydrophobicity and establish WARPs as a broadly distributed class of surface-associated metabolites with structural function in filamentous fungi.

microbiology↗

bioRxiv2019

Analyzing the weak dimerization of a cellulose binding module by sedimentation velocity experiments

Cellulose binding modules (CBMs) are found widely in different proteins that act on cellulose. Because they allow a very easy way of binding recombinant proteins to cellulose, they have become widespread in many biotechnological applications involving cellulose. One commonly used variant is the CBMCipA from Clostridium thermocellum. Here we studied the dimerization of CBMCipA, because we were interested if its solution behavior could have an impact on its use in biotechnical applications. As the principal approach, we used sedimentation velocity analytical ultracentrifugation. To enhance our understanding of the possible interactions, we used molecular dynamics simulations. By analysis of the sedimentation velocity data using a discrete model genetic algorithm we found that the CBMCipA shows a weak dimerization interaction with a dissociation constant KD of about 87 M. As the KD of CBMCipA binding to cellulose is about 0.6 M, we conclude that the dimerization is unlikely to affect cellulose binding. However, at the high concentrations used in some applications of the CMBCipA, its dimerization is likely to have an effect on its solution behavior. The work shows that analytical ultracentrifugation is a very efficient tool to analyze this type of weak interactions. Moreover, we provide here a protocol for data analysis in the program Ultrascan for determining dissociation constants by sedimentation velocity experiments.

biophysics↗