Iron assimilation

The pathogenicity of Erwinia chrysanthemi 3937 on African violets involves at least five pectate lyases (PelA to PelE), one methyl pectin esterase (Pern), encoded by pelA to pelE, pern genes and an iron assimilation system mediated by chiysobactin [1], (Fig. 1). 

This shows that between 6 h and 18 h after inoculation, pelD uidA expression does not depend on KdgR control, but is sensitive to iron assimilation efficiency. 

Enard, C., Diolez, A., and Expert, D. 1988. Systemic virulence of Erwini chrysanthemi 3937 requires a functional iron assimilation system. J. Bacteriol. 170 2419-2426... 

Viswanathan, V. K., Edelstein, P. H., Dumais Pope, C. and Ciancotto, N. P. (2000). The Legionella pneumophila iraAB locus is required for iron assimilation, intracellular infection, and virulence, Infect. Immun., 68, 1069-1079. 

Iron assimilation by phytoplankton. Source From Gerringa, L. J. A., et al. (2000). Marine Chemistry 68, 235-346. 

Emery T (1987) Reductive Mechanisms of Iron Assimilation. In Winkelmann G, van der Hehn D, Neilands JB (eds) Iron Transport in Microbes, Plants and Animals. VCH, Weinheim, p 235... 

Campbell, W.H. Redinbaugh, M.G. (1984). Ferric-citrate reductase activity of nitrate reductase and its role in iron assimilation by plants. Journal of Plant Nutrition 7, 799-806. 

The general properties of siderophores have been described extensively (2), and up-to-date lists of the individual compounds, their sources from aerobic and facultative aerobic species, and their properties have been published (3,4, 5). (Porphyrin Products, P. O. Box 31, Logan, UT 84321, sell a limited number of siderophores.) The earlier literature on iron assimilation by microbes, including enteric species, may be found elsewhere (6,7). For information on the chemical constitution and physiological role of the outer membrane of enteric bacteria, the reader is referred to Nakae and Nikaido (8). 

Advantages of Enteric Bacteria for Studies of Microbial Iron Assimilation... 

Ferrichrome transport in E. coli adheres to mechanism 2, since the nondissociable chromic complex enters the cell at the same rate as the iron. It is somewhat mysterious that the ligand is so efficiently rejected in the more rapid phase of siderophore iron assimilation. The ligand— again as the chelate compound—enters the cell at a substantially slower rate. 

C. albicans and related Candida spp. are prototrophic, which contributes to establish virulence. Uracyl or adenine auxotrophy diminishes the virulence of C. albicans [3,4]. Efficient iron assimilation is also essential for C. albicans virulence [5]. Since prototrophy is also found in many other yeasts which are not necessarily pathogenic, it is conceivable that C. albicans must possess traits which make this species more adapted than others to overcome the mucosal... 

In addition to the ferritin from L. innocua already mentioned, a variety of proteins show structures and iron assimilation activities similar to Dps, although they do not bind DNA. These include the Dpr (Dps-like peroxide resistance) protein from Streptococcus mutans, Dip from Bacillus anthracis and the neutrophil-activating protein from Helicobacter pylori, HP-NAP. ... 

In vivo Mossbauer spectroscopic investigations on the time course of iron assimilation revealed that siderophores... 

In microbial iron assimilation, one mechanism for the release of iron from siderophores is the enzymatic reduction to the Fe state. Siderophore stability constants are much lower for Fe +, which has a lower charge-to-radius ratio. Moreover, ligand exchange reactions for the high-spin Fe ion are much faster than for the Fe ion. Stability constants of ferrous siderophores are experimentally difficult to obtain. Limiting pH-independent redox potentials can be utilized, however, to describe the electrochemical and chemical equilibria between fidly coordinated Fe + and Fe +-siderophore complexes and the uncomplexed Fe(H20)6 + and Fe(H20)e +, respectively, in a simple model as described in equation (5) ... 

Menstrual losses of blood average 28 milligrams monthly. One in four college-age women are iron deficient, possibly due to ignoring the need for increased iron intake prior to and during menstruation. Diseases that cause iron deficiency are colon cancer, hiatal hernia, ulcers, hemorrhoids, bladder tumor, and diverticulosis. Soft drinks high in phosphates cause iron to be excreted in the urine. Lack of copper or manganese in the diet reduces iron assimilation, as does a deficiency of vitamin C. Oxalic acid foods, such as chard and rhubarb, can block iron intake. 

Siderophores are highly specific Fe(III) ligands (formation constants often > 10 ) and are excreted by a wide variety of fungi and bacteria to aid iron assimilation because of the low solubility of Fe + at pH values where most life exists. Siderophores are the most common means of acquisition of iron by bacteria and fungi (Crichton, 1991), and in soil, many different species, including plants, will compete for Fe. Although produced primarily as a means of obtaining iron. 

Effect of other Metals on Iron Assimilation.— Iron metabolism in higher animals appears to be catalysed by traces of copper. Similar effects have been claimed for related metals, including manganese, nickel, and cobalt, but the results of different investigations are at variance. 

The factors concerned with iron metabolism have been the subject of many investigations (Bothwell and Finch, 1962 Gross, 1964 Jacobs and Worwood, 1974). Aspects of the iron transporting system of mitochondria have been outlined recently (Flatmark and Romslo, 1977), while the more specialized processes involved in microbial iron assimilation have been described (Neilands, 1972,1977 Raymond, 1977). 

Kim, D., Li, Y, Horenstein, B.A., and Nakanishi, K. (1990) Synthesis of tunichromes Mm-1 and Mm-2, blood pigments of the iron-assimilating tunicate, Molgula manhattensis. Tetrahedron Lett., 31, 7119-7122. 

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