Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium
Manganese(III) binding to a pyoverdine siderophore produced by a manganese(II)-oxidizing bacterium
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DOI：
10.1016/j.gca.2004.05.038
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发表时间：
2004-12-01
影响因子：
5
通讯作者：
Tebo, BM
中科院分区：
文献类型：
--
作者：
Parker, DL;Sposito, G;Tebo, BM
铁载体（铁（III）的高亲和力螯合剂）在锰的生物地球化学中的可能作用仍然未知。在这里，我们调查的相互作用锰（III）与绿脓菌荧光素型铁载体（PVDMnB 1）产生的模型锰（II）-氧化细菌恶臭假单胞菌菌株MnB 1。PVDMnB 1证实了典型的绿脓菌荧光素行为，涉及：（a）在不存在和存在Fe（III）的情况下，其在350-600 nm处的吸收光谱，（B）其荧光被Fe（III）淬灭，（c）与Fe（III）形成1：1络合物，以及（d）其Fe（III）络合物的热力学稳定常数。PVDMnB 1的Mn（III）络合物具有1：1的Mn：pvd摩尔比，显示出荧光猝灭，并且表现出与PVDMnB 1-Fe（III）或未络合的PVDMnB 1不同的光吸收光谱（A（max）= 408-410 nm）。在培养滤液（pH 8，4 ℃）中，Mn（III）与Fe（III）强烈竞争PVDMnB 1的结合。在柠檬酸盐/PVDMnB 1摩尔比为830（pH 8，4 ℃）时，用柠檬酸盐（一种金属结合配体）平衡，没有检测到Mn从PVDMnB 1复合物中释放出来，而在相同条件下，焦磷酸盐从PVDMnB 1复合物中去除了55%的Mn。大多数PVDMnB 1络合的锰通过与抗坏血酸盐（还原剂）或EDTA（也被Mn（III）氧化的配体）反应而释放。Fe（III）与Mn（III）竞争结合PVDMnB 1的数据用于确定中性物质MnHPVDMnB 1的热力学稳定性常数（标称4 ℃）（log K = 47.5 +/- 0.5，无限稀释参考状态）。该值大于FeHPVDMnB 1的测定值（log K 44.6 +/- 0.5）。这一结果对锰的代谢、溶解度、形态和氧化还原循环以及铁的生物吸收具有重要意义。版权所有（C）2004 Elsevier Ltd.
The possible roles of siderophores (high affinity chelators of iron(Ill)) in the biogeochemistry of manganese remain unknown. Here we investigate the interaction of Mn(III) with a pyoverdine-type siderophore (PVDMnB1) produced by the model Mn(II)-oxidizing bacterium Pseudomonas putida strain MnB1. PVDMnB1 confirmed typical pyoverdine behavior with respect to: (a) its absorption spectrum at 350-600 nm, both in the absence and presence of Fe(III), (b) the quenching of its fluorescence by Fe(III), (c) the formation of a 1:1 complex with Fe(III), and (d) the thermodynamic stability constant of its Fe(III) complex. The Mn(III) complex of PVDMnB1 had a 1:1 Mn:pvd molar ratio, showed fluorescence quenching, and exhibited a light absorption spectrum (A(max) = 408-410 nm) different from that of either PVDMnB1-Fe(III) or uncomplexed PVDMnB1. Mn(III) competed strongly with Fe(III) for binding by PVDMnB1 in culture filtrates (pH 8, 4degreesC). Equilibration with citrate, a metal-binding ligand, did not detectably release Mn from its PVDMnB1 complex at a citrate/PVDMnB1 molar ratio of 830 (pH 8, 4degreesC), whereas pyrophosphate under the same conditions removed 55% of the Mn from its PVDMnB1 complex. Most of the PVDMnB1-complexed Mn was released by reaction with ascorbate, a reducing agent, or with EDTA, a ligand that is also oxidized by Mn(III). Data on the competition for binding to PVDMnB1 by Fe(III) vs. Mn(III) were used to determine a thermodynamic stability constant (nominally at 4degreesC) for the neutral species MnHPVDMnB1 (log K = 47.5 +/- 0.5, infinite dilution reference state). This value was larger than that determined for FeHPVDMnB1 (log K 44.6 +/- 0.5). This result has important implications for the metabolism, solubility, speciation, and redox cycling of manganese, as well as for the biologic uptake of iron. Copyright (C) 2004 Elsevier Ltd.