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排序方式: 共有167条查询结果,搜索用时 15 毫秒
1.
Joanne Screen Eduardo Moya Ian S. Blagbrough Anthony W. Smith 《FEMS microbiology letters》1995,127(1-2):145-149
Abstract Pseudomonas aeruginosa is known to have an inducible uptake system for the enterobacterial siderophore enterobactin. In this work we have examined iron transport mediated by the biosynthetic precursor 2,3-dihydroxybenzoic acid and N -(2,3-dihydroxybenzoyl)- l -serine, a breakdown product of enterobactin. Iron complexed with 2,3-dihydroxybenzoyl-L-serine was transported into P. aeruginosa IA1 via a transport system which is energy-dependent and iron-repressible. The rate of transport was not altered by growing the cells in the presence of either pyoverdin or pyochelin, which have been shown previously to induce transport via that system. Growth of the cells in the presence of enterobactin did cause an increase in the rate of transport, indicating that the complex can be transported by the inducible enterobactin uptake system, but also that a separate system must exist. In contrast, transport of iron complexed with 2,3-dihydroxybenzoic acid was neither iron-repressible nor strongly energy-dependent, from which we conclude that there must be a novel mode of transport not characteristic of iron-siderophore transport systems. 相似文献
2.
Mark S. Thomas 《Biometals》2007,20(3-4):431-452
The Burkholderia cepacia complex (Bcc) is comprised of at least 10 closely related species of Gram-negative proteobacteria that are associated with
infections in certain groups of immunocompromised individuals, particularly those with cystic fibrosis. Infections in humans
tend to occur in the lungs, which present an iron-restricted environment to a prospective pathogen, and accordingly members
of the Bcc appear to possess efficient mechanisms for iron capture. These bacteria specify up to four different types of siderophore
(ornibactin, pyochelin, cepabactin and cepaciachelin) that employ the full repertoire of iron-binding groups present in most
naturally occurring siderophores. Members of the Bcc are also capable of utilising some exogenous siderophores that they are
not able to synthesise. In addition to siderophore-mediated mechanisms of iron uptake, the Bcc possess mechanisms for acquiring
iron from haem and from ferritin. The Bcc therefore appear to be well-equipped for life in an iron-poor environment.
An erratum to this article can be found at 相似文献
3.
Dong W. Choi Young S. Do Corbin J. Zea Marcus T. McEllistrem Sung-W. Lee Jeremy D. Semrau Nicola L. Pohl Clint J. Kisting Lori L. Scardino Scott C. Hartsel Eric S. Boyd Gill G. Geesey Theran P. Riedel Peter H. Shafe Kim A. Kranski John R. Tritsch William E. Antholine Alan A. DiSpirito 《Journal of inorganic biochemistry》2006,100(12):2150
Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ. 相似文献
4.
高灵敏假单胞菌铁载体的平板检测方法 总被引:6,自引:1,他引:5
CAS蓝色检测平板是一种筛选、检测各类细菌铁载体的常用方法,而蔗糖-天冬酰氨培养基被用于假单胞菌产铁载体规律的研究。用天冬氨酸替代天冬酰氨,将CAS蓝色检测液与蔗糖-天冬氨酸培养基(MSA培养基)相结合,得到一种改进的MSA-CAS检测平板。通过对假单胞菌属7个种8个株进行荧光与非荧光铁载体检测方面的比较研究,结果表明MSA-CAS检测平板假单胞菌铁载体的检测灵敏度比通用CAS检测平板高,而且在检测荧光铁载体方面具有荧光背景低、荧光铁载体晕圈明显和晕圈与背景的对比度大的优点。 相似文献
5.
溶藻弧菌铁载体合成及外膜蛋白表达的研究 总被引:3,自引:0,他引:3
初步研究了海洋动物病原菌溶藻弧菌的铁摄取机制。溶藻弧菌能够在高浓度铁螯合剂2-2二联吡啶的培养基中存活。在限铁环境中,溶藻弧菌生长受到抑制,补加铁可以消除这种抑制作用。通过铁载体定量检测,发现分离于发病鱼体的溶藻弧菌MVP01产铁载体量大于分离于海水的菌株No·1·1587。互补实验证明溶藻弧菌的铁载体粗提物能够被铁载体合成缺陷的大肠杆菌突变株AN93利用。在铁限制培养环境中,溶藻弧菌合成了约80kD铁调控外膜蛋白。铁摄取系统在溶藻弧菌的生存和致病性方面,都有重要的作用。 相似文献
6.
Siderophores are low molecular weight organic ligands exuded by some aerobic organisms and plants to acquire Fe under Fe-limited
conditions. The hydroxamate siderophores may sorb to aluminosilicate clays through a variety of mechanisms depending upon
the nature of the clay and of the siderophore along with solution conditions such as pH, ionic strength, and presence of metal
cations. They may also affect metal binding to clays. Here, we review previous studies of siderophore sorption to aluminosilicate
clays; briefly discuss how the techniques of X-ray diffractometry, Fourier-transform infrared spectroscopy, and X-ray absorption
spectroscopy may be applied to such studies; review effects of siderophores on metal sorption to clays; and highlight some
areas for future research. 相似文献
7.
8.
The bacterium Pseudomonas aeruginosa is commonly isolated from the general environment and also infects the lungs of patients with cystic fibrosis (CF). Iron
in mammals is not freely available to infecting pathogens although significant amounts of extracellular iron are available
in the sputum that occurs in the lungs of CF patients. P. aeruginosa has a large number of systems to acquire this essential nutrient and many of these systems have been characterised in the
laboratory. However, which iron acquisition systems are active in CF is not well understood. Here we review recent research
that sheds light on how P. aeruginosa obtains iron in the lungs of CF patients. 相似文献
9.
Brandon Wayne Alderman 《Inorganica chimica acta》2009,362(6):1787-1529
The iron overload drug desferal (desferrioxamine B) forms the stable iron complex ferrioxamine B. The reduction potential of ferrioxamine B (Eo = −482 mV versus NHE pH 7) prohibits its reduction by biological reducing agents such as ascorbate, but it was found that the iron(II) chelator 2,2′-bipyridine (bipy) facilitates this reduction. Evidence is given to support the formation of a ternary complex between iron, bipy, and desferrioxamine B as the key step in facilitating the reduction. The equilibrium constant for the formation of the ternary complex was found to be 8.9 × 107 and ternary complex formation is explained in terms of a three step mechanism. The mechanism for the reduction of ferrioxamine B is discussed in terms of rapidly established pre-equilibria which include ternary complex formation, ascorbic acid deprotonation, and encounter complex formation between ascorbate and the ternary complex. These equilibria are followed by rate limiting reduction of the ternary complex. Bipy was found to be a similar facilitator to sulfonated bathophenanthroline for the reduction of ferrioxamine B by ascorbate. 相似文献
10.
《Mycoscience》2020,61(3):101-110
Over 90 years have passed since Alexander Fleming's discovery of penicillin, the first recognized, naturally occurring antibiotic. Penicillin is a representative of a group of metabolites produced by large multienzyme complexes [nonribosomal peptide synthetases (NRPSs)] in a ribosome-independent fashion. Nonribosomal peptides (NRPs) are structurally diverse metabolites produced almost exclusively by bacteria and fungi. NRPs include bioactive compounds useful for pharmaceutical applications (e.g., antibiotics, antitumor compounds, and immunosuppressants) and therefore much progress has been made in our understanding of medically relevant characteristics of NRPs in the past decades. Natural roles of NRP metabolites, on the other hand, have been largely ignored, and much less is known about the biological/physiological significance of NRPs under natural settings. In the present review, we summarize past and current work on natural functions of NRPs in their fungal producers, with a focus on virulence, development, and stress tolerance, and highlight the diverse roles these small peptide metabolites play. Some NRPs are involved in interactions with host organisms, others work in fungus-environment interfaces, and still others are crucial for vegetative and reproductive development of the producing fungi. 相似文献