Nadeau L J, Spain J C
Armstrong Laboratory, Tyndall Air Force Base, Florida 32403-5323, USA.
Appl Environ Microbiol. 1995 Feb;61(2):840-3. doi: 10.1128/aem.61.2.840-843.1995.
Pseudomonas sp. strain JS51 grows on m-nitrobenzoate (m-NBA) with stoichiometric release of nitrite. m-NBA-grown cells oxidized m-NBA and protocatechuate but not 3-hydroxybenzoate, 4-hydroxy-3-nitrobenzoate, 4-nitrocatechol, and 1,2,4-benzenetriol. Protocatechuate accumulated transiently when succinate-grown cells were transferred to media containing m-NBA. Respirometric experiments indicated that the conversion of m-NBA to protocatechuate required 1 mol of oxygen per mol of substrate. Conversions conducted in the presence of 18O2 showed the incorporation of both atoms of molecular oxygen into protocatechuate. Extracts of m-NBA-grown cells cleaved protocatechuate to 2-hydroxy-4-carboxymuconic semialdehyde. These results provide rigorous proof that m-NBA is initially oxidized by a dioxygenase to produce protocatechuate which is further degraded by a 4,5-dioxygenase.
假单胞菌属菌株JS51能在间硝基苯甲酸（m-NBA）上生长，并按化学计量比释放亚硝酸盐。以m-NBA为生长底物的细胞能氧化m-NBA和原儿茶酸，但不能氧化3-羟基苯甲酸、4-羟基-3-硝基苯甲酸、4-硝基邻苯二酚和1,2,4-苯三酚。当以琥珀酸盐为生长底物的细胞转移到含有m-NBA的培养基中时，原儿茶酸会短暂积累。呼吸测定实验表明，每摩尔底物将m-NBA转化为原儿茶酸需要1摩尔氧气。在18O2存在下进行的转化实验表明，分子氧的两个原子都掺入了原儿茶酸中。以m-NBA为生长底物的细胞提取物将原儿茶酸裂解为2-羟基-4-羧基粘康酸半醛。这些结果提供了确凿的证据，表明m-NBA首先被双加氧酶氧化生成原儿茶酸，原儿茶酸再被4,5-双加氧酶进一步降解。
