Iron Transport in the Enteric Bacteria

Rosenberg, H.; Young, Ian G.

doi:10.1016/b978-0-12-515250-1.50008-4

Cited by 89 publications

(65 citation statements)

References 38 publications

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“…Gram-negative organisms, such as E. coli and Salmonella tvphimurium, possess similar systems (11,21). These systems are controlled, in part, by an induction of outer membrane proteins (11).…”

Section: Discussionmentioning

confidence: 99%

Influence of Iron Deprivation on the Membrane Composition of Anacystis nidulans

Guikema¹,

Sherman²

1984

Plant Physiol.

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Cultures of the cyanobacterium Anacystis nidulans were grown under iron-deficient conditions and then restored by the addition of iron. Membrane proteins from iron-deficient and iron-restored cells were analyzed by lithium dodecyl sulfate-polyacrylamide gradient gel electrophoresis.The incorporation of l3SIsulfate into membrane proteins and lactoperoxidase-catalyzed "5I iodination were used to monitor the rates of polypeptide biosynthesis and surface exposure of membrane proteins, respectively. These polypeptide profiles revealed major differences in the membrane composition of iron-deficient and normal cells. Iron deficiency caused a decrease in the amount of certain important membrane proteins, reflecting a decreased rate of biosynthesis of these peptides. Several photosystem II peptides also showed an increase in surface exposure after iron stress. In addition, iron deficiency led to the synthesis of proteins at 34 and 52 kilodaltons which were not present in normal cells. When iron was restored to a deficient culture, a metabolic sequence was initiated within the first 12 h after the addition of iron which led to phenotypically normal cells. Pulse labeling with I35Sjsulfate during this period demonstrated that iron addition initiates a coordinated pattern of synthesis that leads to the assembly of normal membranes.The thylakoid membranes of cyanobacteria show changes in response to iron deprivation (8,(17)(18)(19) 686 nm. These changes in the biophysical parameters spurred an examination of the Chi-protein arrangement of iron-deficient thylakoids. We observed a loss of the large mol wt Chl-protein complexes normally associated with these membranes (5, 7). Furthermore, we suggested that, by monitoring membrane synthesis following the readdition of iron, we would be able to detect peptides responsible for the altered membrane structure.We have analyzed polypeptide patterns by gel electrophoresis to document the alterations in thylakoid protein composition caused by iron deficiency in A. nidulans. Certain peptides are accumulated in the membrane fraction upon iron stress, while others are lost. Membranes from iron-stressed cells show a different topology, as monitored by the lactoperoxidase-catalyzed iodination of surface-exposed tyrosines. In vivo incorporation of[35S]sulfate into protein was used as a monitor of peptide synthesis during both iron stress and the recovery from iron deficiency. Maximum changes in photosynthetic parameters occurred during the first 7 to 13 h following the addition of iron to a deficient culture. These changes lead to the addition of membrane proteins which are important for normal photosynthetic membrane structure. MATERIALS AND METHODSCells of A. nidulans R2 were obtained and grown in shaking culture as previously described (8). Optimal growth was obtained using BG-I I growth medium. Iron-deficient media was prepared by replacing ferric ammonium citrate with equal molar amounts of ammonium citrate in this medium. Glassware was rinsed thoroughly with glass-distilled H20 p...

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Section: Discussionmentioning

confidence: 99%

Influence of Iron Deprivation on the Membrane Composition of Anacystis nidulans

Guikema¹,

Sherman²

1984

Plant Physiol.

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“…One the other hand, Fe(IIl) can also form strong complexes to organic ligands -particularly to the elements O, N and S (11) -which also have low dissociation constants (17). Complexes with only a few highly specialized ligands have been shown to be capable of being transported into cells (3,16). Thus it has been pointed out that Fe presents a challenging uptake problem to single-cell, water-dwelling organisms at nearly neutral pH (7,9,11,16).…”

Section: Role Of the Ous In The Transport Of Fe And Cumentioning

confidence: 99%

“…Complexes with only a few highly specialized ligands have been shown to be capable of being transported into cells (3,16). Thus it has been pointed out that Fe presents a challenging uptake problem to single-cell, water-dwelling organisms at nearly neutral pH (7,9,11,16). This challenge has been met by some bacteria by secretion of ferric ironophores which can wrest the iron away from precipitates and other complexes and then be transported into the cell, see reviews by HUTNER (7), NEILANDS (1 1) and BYERS (3).…”

Section: Role Of the Ous In The Transport Of Fe And Cumentioning

confidence: 99%

“…This suggests the absence of specialized chelators for Fe transport analogous to the catechols and hydroxamates produced by other unicellular organisms (3,16). The dose response curves of NPI to Fe(III) are not significantly different in the presence or absence of citrate, and this suggests that the Fe(III)-citrate complex is unavailable to the SUS, and that a citrate-de-L. RASMUSSEN ,~ E. ORIAS: Fe and Cu uptake in Tetrahymena pendent uptake system analogous to that in Salmonella does not play a nutritionally significant part in the SUS (18).…”

Section: Fe and Cu Uptake Through The Surface Uptake Systemmentioning

confidence: 99%

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Dual capacity for nutrient uptake in tetrahymena importance of the oral uptake system for Fe and Cu uptake

Rasmussen

Orias

1976

Carlsberg Res. Commun.

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We have reported that a mutant of Tetrahymenapyriformis with heat-sensitive development of the oral apparatus can be grown indefinitely without food vacuoles if the medium is supplemented with folinic acid and a mixture of trace metal salts. We report here that the trace metal mixture can be replaced completely and specifically by salts of iron and copper. Fe(ll) and Fe(lll) are interchangeable. Addition of citrate has proven useful to reduce precipitate formation and improve the reproducibility of growth of the mutant cell. Thus it appears to serve as an Fe buffer. From the increased concentrations of Fe and Cu required to permit good growth of the mutant strain at 37~ we conclude that the oral uptake system plays a much more important role in the case of these two metals than the surface uptake system. The oral uptake system may facilitate Fe uptake in at least two ways: a) by a mechanical concentration of precipitates affected by the ciliary membranelles surrounding the oral cavity and, b) by lowering of the pH of the food vacuole and thereby releasing Fe from precipitates and from complexes which cannot be transported across the membrane as such. The second factor may also be important in Cu uptake. A specific effect of Mg and Fe uptake or retention in the mutant strain growing without food vacuoles has been detected. The significance of this effect remains unclear. Practical implications of the findings are discussed.

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“…These systems depend upon the solubilization and chelation of ferric-ions from insoluble hydroxy-iron polymers by siderophores. Uptake systems have been identified in E. coli for ferrichrome [1 ], rhodoturulic acid [2], aerobactin [3] and citrate [4] as well as for the endongenous chelator enterochelin [5].…”

Section: Introductionmentioning

confidence: 99%