Relation of cell growth and colicin tolerance to vitamin B12 uptake in Escherichia coli

Kadner, Robert J.; Bassford, P J

doi:10.1128/jb.129.1.254-264.1977

Cited by 15 publications

(20 citation statements)

References 29 publications

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“…Vitamin B12 transport assays. Assays of vitamin B12 transport were modified from the procedure of Kadner and Bassford (19). Cells were grown in medium A to the early logarithmic phase, and 3H-labeled vitamin B12 was added to a final concentration of 34 nM (0.23 ,uCi/ml).…”

Section: Methodsmentioning

confidence: 99%

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

DeVeaux¹,

Kadner²

1985

J Bacteriol

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The transport of vitamin B12 in Escheryihia coli requires a specific vitamin B12 receptor protein in the outer membrane and the tonB gene product. In addition, the btuC gene, located at min 38 on the genetic map, has been found to influence vitamin B12 uptake or utilization. The btuC function is required for the growth response to vitamin B12 when the outer membrane transport process (btuB or tonB function) is defective. However, even in a wild-type strain, btuC is required for proper transport of vitamin B12. Additional mutations in the vicinity of btuC were isolated as lac fusions that produced a phenotype similar to that of a btuC mutant. The btuC region was cloned by selection for complementation of a btuC mutation. Complementation testing with plasmids carrying various deletions or transposon TnlOOO insertions demonstrated that the new mutations defined a separate, independently expressed locus, termed btuD. The coding regions for both genes were identified on a 3.4-kilobase HindIll-HincII fragment and were 800 to 1,000 base pairs in length. They were separated by a 600to 800-base-pair region. The gene order in this portion of the chromosome map was found to be pps-zdh-3::TnlO-btuD-btuC-pheS. Expression of Il-galactosidase in the btuD-lac fusion-bearing strains, whether proficient or defective in vitamin B12 transport, was not regulated by the presence of vitamin B12 in the growth medium.

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Section: Methodsmentioning

confidence: 99%

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

DeVeaux¹,

Kadner²

1985

J Bacteriol

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“…Escape from attack Colicins and phage use corrinoid receptors as a point of attack (Bradbeer, Woodrow, & Khalifah, 1976;Di Masi, White, Schnaitman, & Bradbeer, 1973;Kadner & Bassford, 1977). Colicins are toxins secreted by bacteria that can kill other bacteria.…”

Section: Why Are There Different Types Of Corrinoid?mentioning

confidence: 99%

Receptor uptake arrays for vitamin B₁₂, siderophores, and glycans shape bacterial communities

Frank

2017

Ecology and Evolution

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Molecular variants of vitamin B12, siderophores, and glycans occur. To take up variant forms, bacteria may express an array of receptors. The gut microbe Bacteroides thetaiotaomicron has three different receptors to take up variants of vitamin B12 and 88 receptors to take up various glycans. The design of receptor arrays reflects key processes that shape cellular evolution. Competition may focus each species on a subset of the available nutrient diversity. Some gut bacteria can take up only a narrow range of carbohydrates, whereas species such as B. thetaiotaomicron can digest many different complex glycans. Comparison of different nutrients, habitats, and genomes provides opportunity to test hypotheses about the breadth of receptor arrays. Another important process concerns fluctuations in nutrient availability. Such fluctuations enhance the value of cellular sensors, which gain information about environmental availability and adjust receptor deployment. Bacteria often adjust receptor expression in response to fluctuations of particular carbohydrate food sources. Some species may adjust expression of uptake receptors for specific siderophores. How do cells use sensor information to control the response to fluctuations? This question about regulatory wiring relates to problems that arise in control theory and artificial intelligence. Control theory clarifies how to analyze environmental fluctuations in relation to the design of sensors and response systems. Recent advances in deep learning studies of artificial intelligence focus on the architecture of regulatory wiring and the ways in which complex control networks represent and classify environmental states. I emphasize the similar design problems that arise in cellular evolution, control theory, and artificial intelligence. I connect those broad conceptual aspects to many testable hypotheses for bacterial uptake of vitamin B12, siderophores, and glycans.

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“…The energy-dependent steps of uptake after binding to receptor differ for these ligands. For example, mutants tolerant to the E colicins are unaffected in their response to B12 and phage BF23 (16). Participation of the tonB product is necessary for receptor-mediated B12 uptake, but not for the action of the lethal agents which bind to the same receptor (1).…”

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“…Unless specified, cells were harvested by centrifugation at 21°C and washed twice with growth medium without B12. B12 uptake activity was measured as soon as possible after harvest to avoid the extensive loss of uptake activity after inhibition of protein synthesis (16). Assays.…”

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Repression of synthesis of the vitamin B12 receptor in Escherichia coli

Kadner¹

1978

J Bacteriol

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Growth of Escherichia coli K-12 strains in the presence of the vitamin cyanocobalamin (B12) resulted in an 80 to 90% reduction in B12 uptake activity of washed cells. Coincident with the decline in uptake activity was the depression of B12-binding activity in energy-poisoned cells, suggesting that growth in B12 resulted in the repression of synthesis of the B12 receptor protein in the outer membrane. Growth in the presence of B12 led to marked reduction in sensitivity to the E colicins, whose adsorption to cells requires the B12 receptor, and to a decrease in the amount of a band on electropherograms of outer membrane proteins. That polypeptide was also missing from mutants altered at btuB, the locus encoding the B12 receptor. Addition of B12 to growing cultures resulted in the exponential decline in specific activity of B12 uptake, as expected for dilution of functional receptors by further growth. Repression of receptor synthesis appears to be regulated by the level of intracellular, rather than extracellular, B12 and is separate from the regulation of the methionine biosynthetic pathway. Mutants altered in btuC, which are defective in accumulation and retention of B12, exhibit a much lower degree of repressibility.Along with the recent advances in our understanding of the structure of the gram-negative bacterial cell envelope has come an appreciation of its involvement in the uptake of cellular nutrients. Most hydrophilic compounds with molecular weights below 600 apparently pass through the outer membrane by means of relatively nonspecific diffusion pores (23). However, there are several cases in which outer membrane proteins are involved in specific nutrient transport in Escherichia coli. The lamB product, to which phage X adsorbs, facilitates the access of maltose and maltodextrins across the outer membrane to the periplasmic maltose-binding protein (29). The tsx product, to which phage T6 and colicin K adsorb, appears to facilitate uptake of nucleosides at low concentrations (15). Both of these proteins probably function as diffusion pores because their substrate specificity is rather broad and because there is no evidence that the nutrients actually bind to the receptor proteins. For example, the nutrients do not protect sensitive cells against the cognate phage or colicin.In contrast, the btuB product binds vitamin B12 as well as the E colicins and phage BF23; the vitamin can competitively block adsorption of the lethal agents (6,12). Several outer membrane proteins are involved in the transport of various iron chelates. The tonA product binds ferrichrome, colicin M, and phages Ti, T5, and p80 (7); the cbr (feuB, fepA) product binds enterochelin and colicins B and D (26). The mechanism by which these receptors function in nutrient or colicin uptake is not understood.

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Relation of cell growth and colicin tolerance to vitamin B12 uptake in Escherichia coli

Abstract: The uptake of vitamin B12 was measured in cells of Escherichia coli whose growth had been inhibited by any of a variety of treatments. In all cases, the secondary, energy-dependent phase of B12 uptake was depressed in proportion to

Cited by 15 publications

References 29 publications

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

Receptor uptake arrays for vitamin B₁₂, siderophores, and glycans shape bacterial communities

Repression of synthesis of the vitamin B12 receptor in Escherichia coli

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Relation of cell growth and colicin tolerance to vitamin B12 uptake in Escherichia coli

Abstract: The uptake of vitamin B12 was measured in cells of Escherichia coli whose growth had been inhibited by any of a variety of treatments. In all cases, the secondary, energy-dependent phase of B12 uptake was depressed in proportion to

Cited by 15 publications

References 29 publications

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

Transport of vitamin B12 in Escherichia coli: cloning of the btuCD region

Receptor uptake arrays for vitamin B12, siderophores, and glycans shape bacterial communities

Repression of synthesis of the vitamin B12 receptor in Escherichia coli

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Receptor uptake arrays for vitamin B₁₂, siderophores, and glycans shape bacterial communities