UTILIZATION OF MICROBIAL SIDEROPHORES IN IRON ACQUISITION BY OAT
UTILIZATION OF MICROBIAL SIDEROPHORES IN IRON ACQUISITION BY OAT
复制标题
DOI：
10.1104/pp.87.3.680
复制
发表时间：
1988-07-01
期刊：
影响因子：
7.4
通讯作者：
SZANISZLO, PJ
中科院分区：
文献类型：
--
作者：
CROWLEY, DE;REID, CPP;SZANISZLO, PJ
在水培化学条件下研究了燕麦（Arena sativa cv Victory，可能是Avena sativa cv Victory，燕麦栽培品种胜利）对铁的吸收，这种条件要求直接利用微生物铁载体进行铁运输。对从异羟肟酸铁载体（铁色素、铁色素A、辅原卟啉、铁胺b（FOB）和红酵母酸（RA））切下的根吸收铁的速率进行测量，结果表明这五种铁载体都能提供铁，但FOB和RA被优先利用。当根预先处于铁胁迫条件下时，FOB介导的铁吸收增加了四倍，并且涉及一种活性的、铁胁迫诱导的运输系统，该系统被5毫摩尔叠氮化钠或0.5毫摩尔二硝基苯酚抑制。动力学研究表明，当FOB以0.1到50微摩尔浓度供应时，出现部分饱和，表观Km为5微摩尔。当植物实验证实5微摩尔FOB足以满足植物生长时，铁载体介导的运输被铬 - 铁色素（一种含铁铁载体的类似物）抑制。我们的研究结果证实燕麦中存在一种微生物铁载体铁运输系统，该系统在土壤微生物产生和使用的生理浓度范围内起作用。
Iron uptake by oat (Arena sativa cv Victory) was examined under hydroponic chemical conditions that required direct utilization of microbial siderophores for iron transport. Measurements of iron uptake rates by excised roots from the hydroxamate siderophores, ferrichrome, ferrichrome A, coprogen, ferrioxamine b (FOB), and rhodotorulic acid (RA) showed all five of the siderophores supplied iron, but that FOB and RA were preferentially utilized. FOB-mediated iron uptake increased four-fold when roots were preconditioned to iron stress and involved an active, iron-stress induced transport system that was inhibited by 5 millimolar sodium azide or 0.5 millimolar dinitrophenol. Kinetic studies indicated partial saturation with an apparent Km of 5 micromolar when FOB was supplied at 0.1 to 50 micromolar concentrations. When plant experiments confirmed that 5 micromolar FOB was sufficient for plant growth. Siderophore-mediated from transport was inhibited by Cr-ferrichrome, an analog of ferrated siderophore. Our results confirm the existence of a microbial siderophore iron transport system in oat which functions within the physiological concentrations produced and used by soil microorganisms.