Evidence for selective sulfhydryl reactivity in cytochalasin A--mediated bacterial inhibitions.

Cytochalasin A (CA) at 5 × 10^?5$\text{M}$ strongly inhibits glucose transport in Arthrobacter sialophilis. This effect and other bacteriostatic and metabolic inhibitions of gram-positive bacteria are not caused by the closely related congeners cytochalasin B or D. Inhibitions by CA are nullified by prior drug incubation with sulfhydryl compounds. It was also found that the characterized adduct of CA with β-mercaptoethanol is devoid of biological activity. N-ethylmaleimide, p-chloromercuribenzoate and ethacrynic acid (a known, liposoluble, sulfhydryl reactant) were each shown at 5 × 10^?5$\text{M}$ to be relatively ineffective in inhibiting D-glucose transport in $\text{A. sialophilus}$. These observations suggest that CA reacts at the molecular biological level in a site-specific manner.