The inducible citrate-dependent iron transport system in Escherichia coli K12

Frost, G.E.; Rosenberg, H.

doi:10.1016/0005-2736(73)90287-3

Cited by 165 publications

(121 citation statements)

References 18 publications

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“…In this respect, the uptake would be similar to the uptake of other ferric siderophores in other bacteria, for example, ferrischizokinen transport in Bacillus rnegaterium, ferriaerobactin in Aerobacter (Klebsiella) aerogenes 62/ 1, and ferrienterochelin in Escherichia coli (Arceneaux et al, 1973 ;Frost & Rosenberg, 1973). (This could be confirmed if [14C]-or [3H]exochelin of high specific activity could be prepared as this would permit double-labelling experiments at low ferriexochelin concentrations.)…”

Section: Discussionmentioning

confidence: 97%

Iron Transport in Mycobacterium smegmatis: Uptake of Iron from Ferriexochelin

Stephenson

Ratledge

1979

Journal of General Microbiology

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193Exochelins are a group of extracellular iron chelators produced by mycobacteria. Iron uptake by washed suspensions of iron-deficiently grown Mycobacterium smegmatis from 55Fe(III)-exochelin fractions (at about 1 ,UM) was greatest from the fractions containing the compounds that naturally predominate in culture filtrates. Uptake from the major fraction, as well as from combined exochelins, had a K , of about 6 , u~ and was unaffected by the presence of a large excess of desferriexochelin ; it was inhibited by more than 90 yo by electron transport inhibitors, uncouplers of oxidative phosphorylation, thiol reagents and by anaerobiosis and low temperature. Uptake of iron from 55Fe-salicylate, which is mediated by mycobactin, was insensitive to these inhibitors and a 10-fold excess of ferric salicylate did not inhibit 55Fe-exochelin uptake. Thus mycobactin is probably not involved in the transport of iron from ferriexochelin at physiological concentrations. The rate of uptake of iron from 55Fe-exochelin into iron-sufficiently grown cells, which contain less than 0.05 yo of the concentration of mycobactin found in iron-deficiently grown cells, was only slightly lower than the rate of uptake into iron-deficiently grown cells.Uptake of ferri[3H]exochelin, which could only be carried out at high and probably nonphysiological concentrations (about 60 p~) , was also extremely sensitive to metabolic inhibitors suggesting that the whole complex was being transported. At these high external concentrations of ferriexochelin a second, non-saturable, inhibitor-insensitive iron uptake process occurred. This process was inhibited in iron-deficiently grown cells by ferric salicylate and may therefore involve mycobactin. A similar but not identical second system which was not sensitive to ferric salicylate was found in iron-sufficiently grown cells; this might indicate yet another pathway of iron uptake from ferriexochelin.

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Section: Discussionmentioning

confidence: 97%

Iron Transport in Mycobacterium smegmatis: Uptake of Iron from Ferriexochelin

Stephenson

Ratledge

1979

Journal of General Microbiology

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“…Citrate is one of the siderophores of E. coli and ferric citrate is taken up by a transport system that is repressed by Fe 2+ Fur. The ferric citrate transport system is the only iron transport system of E. coli that is induced by the ferric siderophore in the culture medium (Frost and Rosenberg, 1973). The five ferric citrate transport genes fecABCDE form an operon (Pressler et al, 1988;Staudenmaier et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Kim

Stiefel

Plantor

et al. 1997

Molecular Microbiology

134

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“…Nevertheless, E. coli is not wholly indifferent to citrate. It uses a ferric dicitrate transport system for iron acquisition, although citrate does not enter the cell in this process (37,38). It also has a complete tricarboxylic acid cycle, and can thus metabolize citrate internally during aerobic growth on other substrates (39).…”

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confidence: 99%

Historical contingency and the evolution of a key innovation in an experimental population ofEscherichia coli

Blount

Borland

Lenski

2008

Proc. Natl. Acad. Sci. U.S.A.

767

808

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The role of historical contingency in evolution has been much debated, but rarely tested. Twelve initially identical populations of Escherichia coli were founded in 1988 to investigate this issue. They have since evolved in a glucose-limited medium that also contains citrate, which E. coli cannot use as a carbon source under oxic conditions. No population evolved the capacity to exploit citrate for >30,000 generations, although each population tested billions of mutations. A citrate-using (Cit ؉ ) variant finally evolved in one population by 31,500 generations, causing an increase in population size and diversity. The long-delayed and unique evolution of this function might indicate the involvement of some extremely rare mutation. Alternately, it may involve an ordinary mutation, but one whose physical occurrence or phenotypic expression is contingent on prior mutations in that population. We tested these hypotheses in experiments that ''replayed'' evolution from different points in that population's history. We observed no Cit ؉ mutants among 8.4 ؋ 10 12 ancestral cells, nor among 9 ؋ 10 12 cells from 60 clones sampled in the first 15,000 generations. However, we observed a significantly greater tendency for later clones to evolve Cit ؉ , indicating that some potentiating mutation arose by 20,000 generations. This potentiating change increased the mutation rate to Cit ؉ but did not cause generalized hypermutability. Thus, the evolution of this phenotype was contingent on the particular history of that population. More generally, we suggest that historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection.adaptation ͉ experimental evolution ͉ mutation ͉ selection

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The inducible citrate-dependent iron transport system in Escherichia coli K12

Cited by 165 publications

References 18 publications

Iron Transport in Mycobacterium smegmatis: Uptake of Iron from Ferriexochelin

Iron Transport in Mycobacterium smegmatis: Uptake of Iron from Ferriexochelin

Transcription induction of the ferric citrate transport genes via the N‐terminus of the FecA outer membrane protein, the Ton system and the electrochemical potential of the cytoplasmic membrane

Historical contingency and the evolution of a key innovation in an experimental population ofEscherichia coli

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