Cyanobacterial Siderophores—Physiology, Structure, Biosynthesis, and Applications

Siderophores are low-molecular-weight metal chelators that function in microbial iron uptake. As iron limits primary productivity in many environments, siderophores are of great ecological importance. Additionally, their metal binding properties have attracted interest for uses in medicine and bioremediation. Here, we review the current state of knowledge concerning the siderophores produced by cyanobacteria. We give an overview of all cyanobacterial species with known siderophore production, finding siderophores produced in all but the most basal clades, and in a wide variety of environments. We explore what is known about the structure, biosynthesis, and cycling of the cyanobacterial siderophores that have been characterized: Synechobactin, schizokinen and anachelin. We also highlight alternative siderophore functionality and technological potential, finding allelopathic effects on competing phytoplankton and likely roles in limiting heavy-metal toxicity. Methodological improvements in siderophore characterization and detection are briefly described. Since most known cyanobacterial siderophores have not been structurally characterized, the application of mass spectrometry techniques will likely reveal a breadth of variation within these important molecules.

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Bioaccumulation of silver and the isolation of metal-binding protein from P.diminuta

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132001000300001 ◽

2001 ◽

Vol 44 (3) ◽

pp. 223-225 ◽

Cited By ~ 18

Author(s):

Zaharah Ibrahim ◽

Wan Azlina Ahmad ◽

Abu Bakar Baba

Keyword(s):

Molecular Weight ◽

Metal Binding ◽

Metal Uptake ◽

Silver Ions ◽

Low Molecular Weight ◽

Early Exponential Phase ◽

Binding Properties ◽

Bacterial Cultures ◽

Sds Page ◽

Pseudomonas Diminuta

A silver uptake study by Pseudomonas diminuta was carried out by growing the bacteria in a chloride-free medium (CFM) containing silver ions (50 muM) in a batch culture. From the results, it was found that higher amounts of silver were accumulated inside the cell during early exponential phase compared to the amount bound at the cell surface. This suggested a possible mechanism for metal uptake during bacterial growth. In view of this, attempts were made to isolate proteins which might be associated with silver-binding properties from cultures of P.diminuta grown in the presence and absence of silver. The proteins were first extracted from the bacterial cultures by precipitation with ammonium sulfate followed by purification using isoelectric focussing and SDS-PAGE. Results of the experiment showed the presence of low molecular weight and high molecular weight proteins containing silver with pI values ranging from 2.0 to 9.0 for bacteria grown in the presence of silver.

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Characterization of the DNA- and Metal-Binding Properties of Vibrio anguillarum Fur Reveals Conservation of a Structural Zn2+ Ion

Journal of Bacteriology ◽

10.1128/jb.182.21.6264-6267.2000 ◽

2000 ◽

Vol 182 (21) ◽

pp. 6264-6267 ◽

Cited By ~ 27

Author(s):

Ekaterina E. Zheleznova ◽

Jorge H. Crosa ◽

Richard G. Brennan

Keyword(s):

Metal Binding ◽

Iron Uptake ◽

Vibrio Anguillarum ◽

Zinc Ion ◽

Ferric Uptake Regulator ◽

Binding Properties ◽

E Coli ◽

Solution Studies

ABSTRACT The ferric uptake regulator, Fur, represses iron uptake and siderophore biosynthetic genes under iron-replete conditions. Here we report in vitro solution studies on Vibrio anguillarum Fur binding to the consensus 19-bp Escherichia coli iron box in the presence of several divalent metals. We found that V. anguillarum Fur binds the iron box in the presence of Mn2+, Co2+, Cd2+, and to a lesser extent Ni2+ but, unlike E. coli Fur, not in the presence of Zn2+. We also found that V. anguillarum Fur contains a structural zinc ion that is necessary yet alone is insufficient for DNA binding.

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A new family of fluorescent calcium indicators designed to resist leakage or for measuring calcium near membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168578 ◽

1994 ◽

Vol 52 ◽

pp. 168-169

Author(s):

Martin Poenie ◽

Akwasi Minta ◽

Charles Vorndran

Keyword(s):

Metal Binding ◽

Acetoxymethyl Ester ◽

Binding Properties ◽

Fura 2 ◽

New Family ◽

Anion Transporter ◽

Calcium Indicator ◽

Calcium Indicators ◽

High Calcium ◽

Intracellular Compartmentalization

The use of fura-2 as an intracellular calcium indicator is complicated by problems of rapid dye leakage and intracellular compartmentalization which is due to a probenecid sensitive anion transporter. In addition there is increasing evidence for localized microdomains of high calcium signals which may not be faithfully reported by fura-2.We have developed a new family of fura-2 analogs aimed at addressing some of these problems. These new indicators are based on a modified bapta which can be readily derivatized to produce fura-2 analogs with a variety of new properties. The modifications do not affect the chromophore and have little impact on the spectral and metal binding properties of the indicator. One of these new derivatives known as FPE3 is a zwitterionic analog of fura-2 that can be loaded into cells as an acetoxymethyl ester and whose retention in cells is much improved. The improved retention of FPE3 is important for both cuvettebased measurements of cell suspensions and for calcium imaging.

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