RELATIONSHIP BETWEEN TONB LOCUS AND IRON TRANSPORT IN ESCHERICHIA-COLI
RELATIONSHIP BETWEEN TONB LOCUS AND IRON TRANSPORT IN ESCHERICHIA-COLI
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DOI：
10.1128/jb.124.2.704-712.1975
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发表时间：
1975-01-01
影响因子：
3.2
通讯作者：
ROSENBERG, H
中科院分区：
文献类型：
--
作者：
FROST, GE;ROSENBERG, H
当一株不能合成铁转运化合物肠切素的大肠杆菌（arcB-）被转导到tonB-时，它对噬菌体phil80产生耐药性，同时失去对肠切素的生长反应和运输铁复合物的能力。然而，肠切素前体（莽草酸盐和2,3-二羟基苯甲酸酯）仍然通过肠切素的合成支持生长。二羟基苯甲酸盐在低浓度下比在高浓度下表现为较好的生长因子。有证据表明，tonB-菌株缺乏摄取铁肠切素和吸附噬菌体80所必需的外膜成分。因此，尽管铁-肠螯素不能从外部穿透细胞表面，但在包膜内形成的复合物可以正常运输到细胞内。aroB-， tonB-突变体也缺乏对柠檬酸盐和各种羟酸盐铁色素的生长反应，这些铁色素通过诱导运输系统支持tonB+亲本菌株的生长。在柠檬酸盐存在的情况下，aroB-， tonB-突变体不能运输铁，但对未配合铁的低亲和力摄取以及氨基酸和磷酸盐的运输未受到损害。因此，tonB位点影响所有已知的铁的主动转运系统，可能表明它们具有一些共同的外膜成分。
When a strain (arcB-) of Escherichia coli, unable to synthesize the iron transport compound enterochelin, was transduced to tonB-, it became resistant to phage phi80 and simultaneously lost the growth response to enterochelin and the ability to transport its iron complex. However, enterochelin precursors (shikimate and 2,3-dihydroxybenzoate) still supported growth, via the synthesis of enterochelin. Dihydroxybenzoate was a better growth factor at a low concentration than it was at higher levels. The evidence suggests that tonB- strains lack an outer membrane component necessary both for the uptake of ferric-enterochelin and for the adsorption of phage phi80. Thus, although ferric-enterochelin cannot penetrate the cell surface from outside, the complex that is formed within the envelope is transported normally into the cell. The aroB-, tonB- mutant also lacked growth reponses to citrate and various hydroxamate siderochromes, which supported growth in the tonB+ parent strain via inducible transport systems for their ferric complexes. The aroB-, tonB- mutant was unable to transport iron in the presence of citrate, but the low-affinity uptake of uncomplexed iron and the transport of amino acids and phosphate were unimpaired. The tonB locus, thus, affects all the known active transport systems for iron, possibly indicating that they share some common outer membrane component.