The enzyme macrophomate synthase converts 5-acetyl-4-methoxy-6-methyl-2-pyrone to 4-acetyl-3-methoxy-5-methyl-benzoic acid ( macrophomic acid ) through an unusual intermolecular Diels-Alder reaction ( "'Scheme 1 "').
22.
The systematic name of this enzyme is "'2-pyrone-4, 6-dicarboxylate lactonase "'but is also known as LigI . This enzyme is found to play an important role in the metabolism of lignin-derived aromatic compounds in both the syringate degradation pathway and the protocatechuate 4, 5-cleavage pathway.
23.
When activated by external treatments such as high temperature ( ), exposure to vapors of toxic solvents, or contact with a water-toluene mixture, " T . caerulea " produces an antibiotic named cortalcerone ( 2-hydroxy-6H-3-pyrone-2-carboxaldehyde hydrate ), that inhibits the growth of " Streptococcus pyogenes ".
24.
"' Myxopyronin "'( "'Myx "') is an alpha-pyrone antibiotic, the first in a new class of inhibitors of bacterial RNA polymerase ( RNAP ) that target switch 1 and switch 2 of the RNAP " switch region . " Rifamycin antibacterial agents, which are first-line treatments for tuberculosis, and lipiarmycin ( fidaxomicin, Dificid ) also target RNAP, but target different sites in RNAP . Myxopyronin does not have cross-resistance with rifamycins and lipiarmycin.
