Distinct echinocandin responses of Candida albicans and Candida auris cell walls revealed by solid-state NMR

Invasive candidiasis affects 1.6 million people annually, with high mortality among immunocompromised and hospitalized patients. Echinocandins are frontline antifungals, but rising resistance limits their efficacy. Here, we show that Candida albicans and multidrug-resistant Candida auris share a conserved cell wall architecture yet differ markedly in their adaptive responses to echinocandins. Solid-state NMR reveals that both species possess a rigid inner layer of tightly associated chitin microfibrils and β-1,3-glucans, supported by a flexible matrix of β-1,6-glucans and additional β-1,3-glucans. Outer mannan fibrils rely on α-1,2-linked sidechains to maintain contact with the inner wall. In both species, caspofungin rigidifies β-1,6-glucans and mannan sidechains and reduces water permeability during β-1,3-glucan depletion; however, C. albicans undergoes wall thickening and alterations in chitin and glucan dynamics, whereas C. auris maintains integrity through β-1,6-glucan upregulation. Deletion of KRE6a, which encodes β-1,6-glucan synthase, reduces echinocandin susceptibility in C. auris, further highlighting β-1,6-glucan's critical role in adaptive remodeling.