Fig. 5: Intermolecular contacts in 3-day-old apo and caspofungin-treated A. fumigatus. | Nature Communications

Fig. 5: Intermolecular contacts in 3-day-old apo and caspofungin-treated A. fumigatus.

From: Adaptative survival of Aspergillus fumigatus to echinocandins arises from cell wall remodeling beyond β−1,3-glucan synthesis inhibition

Fig. 5

a DNP enhances NMR sensitivity of the caspofungin-treated 3-day-old sample by 17-fold when microwave (MW) is activated. Inset shows the DNP sample with 30 mg hydrated mycelial material enclosed in a 3.2-mm sapphire rotor. Dash lines mark the baseline of the spectra. b DNP 2D 15N-13C correlation spectra of caspofungin-treated sample. Interactions happen between the 15N-site of the chitin amide (ChNH) or chitosan amine (CsN) and the carbons of polysaccharides. For example, CsN-A1 represents the cross peak between chitosan nitrogen with α−1,3-glucan carbon 1. c, DNP 2D 13C-13C correlation spectra of caspofungin-treated sample. Most interactions happen between α-glucan and chitin. The carbonyl region showed four types of chitin signals. d Site-specific summary of intermolecular cross peaks identified among different polysaccharides. Diagonal regions exhibit intramolecular cross peaks. Off-diagonal regions show intermolecular interactions happening only in the apo sample (green), only in the drug-treated sample (blue), or in both samples (yellow). Strong intermolecular interactions from short-mixing spectra are marked with asterisks. The plot can be asymmetric relative to the diagonal due to the directionality of polarization transfer, e.g., Ch1-A3 differs from A3-Ch1. The left and bottom axes indicate the carbohydrate carbon numbers observed in indirect (ω1) and direct (ω2) spectral dimensions. Representative short-range interactions observed during 1 μs all-atom MD are shown between e, chitin, and glucans, and f, chitosan, and other polymers. Atoms in gray, red, blue, and white represent carbon, oxygen, nitrogen, and hydrogen, respectively. Packing interactions within 5 Å are highlighted. g Contact map of intermolecular interactions within 5 Å identified in MD models. The coordination number (see Methods) represents the number of contacts between two carbon sites of different polysaccharides. Magenta lines separate the sections of chitin/chitosan (Ch: chitin; Cs: chitosan; Ch-Cs: chitin-chitosan copolymer), α−1,3-glucan (A), and β-glucans (B: linear β−1,3-glucan; G: β−1,3/1,4-glucan; BBr: β−1,3/1,6-glucan). Carbon and nitrogen numbers are provided on both axes (M: Me or methyl; C’ carbonyl). Regions boxed in black highlight extensive interactions.

Back to article page