Theoretical conformational analysis of cross-linking bonds in fungal hydrophobin from Aspergillus fumigatus.

Aspergillus fumigatus is a common saprophytic filamentous fungus that plays a crucial role in nutrient cycling but can become an opportunistic pathogen, posing a significant threat to immunocompromised individuals by causing invasive aspergillosis. A key feature of A. fumigatus is the presence of hydrophobins-small amphipathic proteins that form a protective rodlet layer on conidial surfaces, facilitating biofilm formation and immune evasion. This rodlet structure, stabilized by cross-linking disulfide bonds, provides resistance to desiccation, oxidative stress, and immune defenses, making these cross-links a compelling target for study. In this work, we employ all-atom simulations, incorporating quantum mechanics/molecular mechanics (QM/MM) calculations, to evaluate the energy and conformational effects of cross-linking disulfide bonds (CL1, CL2, CL3, and CL4) in the rodlet assembly. By integrating QM/MM approaches, we achieve a detailed representation of the electronic and structural properties of these bonds within the complex rodlet layer, gaining deeper insights into their essential role in maintaining the stability and integrity of the RodA hydrophobin protein from A. fumigatus conidial surface. We identify a group of ten residues that influence directly in the cross-linking, with Gln23 and Lys17 emerging as key candidates for experimental mutation to control rodlet assembly. Our findings shed light on the molecular mechanisms underlying rodlet formation and highlight potential targets for disrupting this protective layer, offering promising avenues for antifungal strategies.