Junker F, Leisinger T, Cook A M
Institute of Microbiology, Swiss Federal Institute of Technology, Zurich.
Microbiology (Reading). 1994 Jul;140 ( Pt 7):1713-22. doi: 10.1099/13500872-140-7-1713.
Alcaligenes sp. strain O-1 utilizes three sulphonated aromatic compounds as sole sources of carbon and energy for growth in minimal salts medium-benzenesulphonate (BS), 4-toluenesulphonate (TS) and 2-aminobenzenesulphonate (2AS). The degradative pathway(s) in 2AS-grown cells are initiated with membrane transport, NADH-dependent dioxygenation and meta ring cleavage. The specific activity of the NADH-dependent dioxygenation(s) varied with the growth phase and was maximal near the end of exponential growth for each growth substrate. Cells were harvested at this point from BS-, TS- and 2AS-salts medium. Cells grown with each sulphonated substrate could oxygenate all three compounds, but only 2AS-grown cells consumed 2 mol O2 per mol 2AS or BS or TS. BS- and TS-grown cells consumed 2 mol O2 per mol BS or TS but failed to oxygenate the product of oxygenation of 2AS, 3-sulphocatechol (3SC). These observations were repeated with cell extracts and we concluded that there were two sets of desulphonative pathways in the organism, one for 2AS and one for BS and TS. We confirmed this hypothesis by separating the degradative enzymes from 2AS-, BS- or TS-grown cells. A 2AS dioxygenase system and a 3SC-2,3-dioxygenase (3SC23O) were detected in 2AS-grown cells only. In both BS- and TS-grown cells a dioxygenase system for BS and TS was observed as well as a principal catechol 2,3-dioxygenase (C23O-III), neither of which was present in 2AS-grown cells. The 3SC23O was purified to near homogeneity, found to be monomeric (M(r) 42,000), and to catalyse 2,3-dioxygenation to a product that decayed spontaneously to sulphite and 2-hydroxymuconate. The 2AS dioxygenase system could cause not only deamination of 2AS but also desulphonation of BS and TS. The BS dioxygenase could desulphonate BS and apparently either desulphonate or deaminate 2AS. Strain O-1 thus seems to contain two putative, independently regulated operons involving oxygenation and spontaneous desulphonation(s). One operon encodes at least the 2AS dioxygenase system and 3SC23O whereas the other encodes at least the BS/TS dioxygenase system and C23O-III.
产碱菌属菌株O-1利用三种磺化芳香族化合物作为唯一的碳源和能源，在最低盐培养基中生长——苯磺酸盐（BS）、4-甲苯磺酸盐（TS）和2-氨基苯磺酸盐（2AS）。在以2AS生长的细胞中，降解途径始于膜转运、依赖NADH的双加氧作用和间位环裂解。依赖NADH的双加氧作用的比活性随生长阶段而变化，并且对于每种生长底物，在指数生长接近结束时达到最大值。此时从BS、TS和2AS盐培养基中收获细胞。用每种磺化底物生长的细胞可以氧化所有三种化合物，但只有以2AS生长的细胞每摩尔2AS或BS或TS消耗2摩尔氧气。以BS和TS生长的细胞每摩尔BS或TS消耗2摩尔氧气，但不能氧化2AS氧化产物3-磺基邻苯二酚（3SC）。用细胞提取物重复了这些观察结果，我们得出结论，该生物体中有两组脱硫途径，一组用于2AS，另一组用于BS和TS。我们通过从以2AS、BS或TS生长的细胞中分离降解酶来证实这一假设。仅在以2AS生长的细胞中检测到2AS双加氧酶系统和3SC-2,3-双加氧酶（3SC23O）。在以BS和TS生长的细胞中，观察到用于BS和TS的双加氧酶系统以及主要的儿茶酚2,3-双加氧酶（C23O-III），而这两种酶在以2AS生长的细胞中均不存在。3SC23O被纯化至接近同质，发现是单体（相对分子质量42,000），并催化2,3-双加氧作用生成一种自发降解为亚硫酸盐和2-羟基粘康酸的产物。2AS双加氧酶系统不仅可以导致2AS脱氨基，还可以导致BS和TS脱硫。BS双加氧酶可以使BS脱硫，并且显然可以使2AS脱硫或脱氨基。因此，菌株O-1似乎包含两个假定的、独立调控的操纵子，涉及氧化作用和自发脱硫作用。一个操纵子至少编码2AS双加氧酶系统和3SC23O，而另一个操纵子至少编码BS/TS双加氧酶系统和C23O-III。
