ANAEROBIC FUMARATE TRANSPORT IN ESCHERICHIA-COLI BY AN FNR-DEPENDENT DICARBOXYLATE UPTAKE SYSTEM WHICH IS DIFFERENT FROM THE AEROBIC DICARBOXYLATE UPTAKE SYSTEM
ANAEROBIC FUMARATE TRANSPORT IN ESCHERICHIA-COLI BY AN FNR-DEPENDENT DICARBOXYLATE UPTAKE SYSTEM WHICH IS DIFFERENT FROM THE AEROBIC DICARBOXYLATE UPTAKE SYSTEM
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DOI：
10.1128/jb.174.17.5533-5539.1992
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发表时间：
1992-09-01
影响因子：
3.2
通讯作者：
UNDEN, G
中科院分区：
文献类型：
--
作者：
ENGEL, P;KRAMER, R;UNDEN, G
以富马酸盐为电子受体厌氧生长的大肠杆菌能够通过特定的运输系统吸收c4 -二羧酸盐。该系统在所有测试参数不同于已知的有氧c4 -二羧酸转运体。与好氧系统相比，厌氧系统显示出更高的富马酸转运速率（95 mu-mol/g[干重]/min比30 mu-mol/g/min）和更高的K(m)s （400 vs 30 mu-m）。缺乏需氧二羧酸盐摄取系统的突变体能够以富马酸呼吸为代价进行厌氧生长，并且在厌氧生长后以野生型速率运输二羧酸盐，而在需氧生长后则不能。通过用二羧酸预负荷细菌来刺激厌氧系统的运输。厌氧转运系统可催化二羧酸的同源和异源反端口，而好氧转运系统仅在单向模式下运作。厌氧反端口仅在fnr+背景下厌氧生长的细菌中可测量。此外，休眠细菌与生理电子受体（如O2、硝酸盐、二甲基亚砜和富马酸盐）孵育可抑制该系统。这种抑制作用因还原剂的存在而逆转。这表明该系统的生理作用是在富马酸呼吸条件下的富马酸/琥珀酸反转运。
Escherichia coli grown anaerobically with fumarate as electron acceptor is able to take up C4-dicarboxylates by a specific transport system. The system differs in all tested parameters from the known aerobic C4-dicarboxylate transporter. The anaerobic transport system shows higher transport rates (95-mu-mol/g [dry weight] per min versus 30-mu-mol/g/min) and higher K(m)s (400 versus 30-mu-M) for fumarate than for the aerobic system. Mutants lacking the aerobic dicarboxylate uptake system are able to grow anaerobically at the expense of fumarate respiration and transport dicarboxylates with wild-type rates after anaerobic but not after aerobic growth. Transport by the anaerobic system is stimulated by preloading the bacteria with dicarboxylates. The anaerobic transport system catalyzes homologous and heterologous antiport of dicarboxylates, whereas the aerobic system operates only in the unidirectional mode. The anaerobic antiport is measurable only in anaerobically grown bacteria with fnr+ backgrounds. Additionally, the system is inhibited by incubation of resting bacteria with physiological electron acceptors such as O2, nitrate, dimethyl sulfoxide, and fumarate. The inhibition is reversed by the presence of reducing agents. It is suggested that the physiological role of the system is a fumarate/succinate antiport under conditions of fumarate respiration.