Pyruvate-triggered TCA cycle regulation in Staphylococcus aureus promotes tolerance to betamethasone valerate.

Staphylococcus aureus is a resident skin bacterium involved in the exacerbation of atopic dermatitis. Here we report that S. aureus regulates the tricarboxylic acid (TCA) cycle via the production of pyruvate for tolerance to betamethasone valerate (BV), an anti-inflammatory drug used in the treatment of atopic dermatitis. The addition of BV or clobetasol propionate to the medium among 5 different anti-inflammatory steroids delayed the growth of S. aureus. Comprehensive gene expression analysis by RNA-seq revealed that BV increased the expression of genes related to glycolysis in S. aureus. Pyruvate, a product of glycolysis, suppressed the S. aureus growth inhibition by BV. The addition of oxaloacetate, a compound in the TCA cycle biosynthesized from pyruvate, was also suppressed the inhibitory effect of BV. Malonate, an inhibitor of succinate dehydrogenase in the TCA cycle, increased the inhibitory effect of BV on the growth of S. aureus. These findings suggest that S. aureus promotes tolerance to BV, an anti-inflammatory steroid, by regulating the TCA cycle via the production of pyruvate.

Peripherally cyclometalated iridium complexes of dipyridylporphyrin.

Two types of novel iridium pincer complexes bearing a porphyrin backbone were synthesized and characterized from dipyridylporphyrin. One of the complexes has a Lewis acidic site on the iridium center in the mer-coordination mode. The other complex takes the fac-coordination, which is rarely observed in benzene-based pincer complexes.