Study of Microbial Evolution through Loss of Biosynthetic Functions: Establishment of “Defective” Mutants

Zamenhof, Stephen; Eichhorn, Herbert H.

doi:10.1038/216456a0

Cited by 144 publications

(73 citation statements)

References 11 publications

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“…Indeed, Koch (1983) observed in a series of very carefully executed chemostat studies that the depression of growth rate associated with production of b -galactosidase, in the absence of permease expression, was very much lower than that estimated earlier (Novick and Weiner, 1957;Zamenhof and Eichhorn, 1967). He interpreted this discrepancy as the expression of a reserve protein synthetic capacity that could meet the demand for translation of the gratuitous protein.…”

Section: Protein Burdenmentioning

confidence: 99%

“…This quantity has been a source of interest since the very first chemostat experiments were carried out (Novick and Weiner, 1957;Zamenhof and Eichhorn, 1967). In these studies, the bacterial growth-rate differences were measured for pairs of strains that were induced and uninduced for a gratuitious protein such as b -galactosidase, or that were auxotrophic and prototrophic for an amino acid that was supplied in the growth medium.…”

Section: Protein Burdenmentioning

confidence: 99%

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Bacterial growth inhibition by overproduction of protein

Kurland

Dong

1996

Molecular Microbiology

149

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SummaryMulticopy plasmids that have been engineered to produce large quantitites of a single gratuitous (nonfunctional, non-toxic) protein are often problematic. When fully induced, these engineered constructions produce very sick bacteria. The reasons for this may be found in the physiology of wild-type laboratory strains that have been selected to grow at maximum rates with optimal quantities of their proteins. Such bacteria apparently experience the accumulation of gratuitous proteins as an internal shift down and they respond to this with a starvation response. Unlike the shift down associated with a change of growth media, the production of large quantities of gratuitous protein is not associated with a new preprogrammed steady-state of balanced growth. Consequently, the starvation response continues until the bacteria commit suicide by, among other things, destroying their ribosomes.

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Section: Protein Burdenmentioning

confidence: 99%

Section: Protein Burdenmentioning

confidence: 99%

Bacterial growth inhibition by overproduction of protein

Kurland

Dong

1996

Molecular Microbiology

149

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“…Indeed, analysing cocultures of two E. coli genotypes that both required a different amino acid to grow, yet produced increased amounts of others, revealed a significant fitness advantage of cooperative cross-feeding relative to prototrophic WT cells 56 . Especially, the tremendous fitness advantage auxotrophic bacteria gain when the required metabolite is supplied externally [56][57][58] should exert a strong selection pressure that favours cross-feeding of essential metabolites among bacterial cells. The enormous variation in gene content that is commonly found among different genomes of E. coli 59,60 , together with the observation that often seemingly essential biosynthetic functions are lost 56 may reflect the ability of E. coli to compensate its metabolic deficiencies by connecting to other cells.…”

Section: Greenmentioning

confidence: 99%

Metabolic cross-feeding via intercellular nanotubes among bacteria

et al. 2015

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Bacteria frequently exchange metabolites by diffusion through the extracellular environment, yet it remains generally unclear whether bacteria can also use cell-cell connections to directly exchange nutrients. Here we address this question by engineering cross-feeding interactions within and between Acinetobacter baylyi and Escherichia coli, in which two distant bacterial species reciprocally exchange essential amino acids. We establish that in a well-mixed environment E. coli, but likely not A. baylyi, can connect to other bacterial cells via membranederived nanotubes and use these to exchange cytoplasmic constituents. Intercellular connections are induced by auxotrophy-causing mutations and cease to establish when amino acids are externally supplied. Electron and fluorescence microscopy reveal a network of nanotubular structures that connects bacterial cells and enables an intercellular transfer of cytoplasmic materials. Together, our results demonstrate that bacteria can use nanotubes to exchange nutrients among connected cells and thus help to distribute metabolic functions within microbial communities.

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“…You synthesize toxic compounds that make caterpillars and mice sick and maybe die, like canavanine in lima beans and alfalfa sprouts [11][12][13][14]. Or, you make yourself nutritionally deficient for those multiply auxotrophic, plant-eating animals [15,16]." Janis and Maura looked at each other and rolled their eyes.…”

Section: Stage 4 -Nothing In Biology Makes Sense Except Inmentioning

confidence: 99%

Plants versus animals in the dining hall: A problem‐based learning problem

White¹

2002

Biochem Molecular Bio Educ

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This five-stage problem explores amino acid metabolism in the context of a story about a college student who chooses to become a vegetarian against the best wishes of her mother. It requires students to analyze isotopic data from classic experiments in nutritional biochemistry and explain the results in terms of now known metabolic pathways. It provides an evolutionary perspective on the meaning of essential and nonessential amino acids and on the production of secondary metabolites from amino acids by plants. Groups of students working in a problem-based learning environment integrate these ideas into concept map to complete the problem.Keywords: Problem-based learning, amino acid metabolism, isotopic tracers, nutrition, secondary metabolites, evolution, concept map.With the increasing amount of information suitable for biochemistry survey courses, instructors must make hard choices about what to include and what to delete. Often, amino acid metabolism gets brief coverage. Other than a general discussion of the source of nitrogen entering the urea cycle and transamination reactions, the numerous biosynthetic and catabolic pathways of amino acid metabolism are left for an advanced course. At the University of Delaware, that advanced course is Intermediary Metabolism, an optional three-credit course taken primarily by senior majors in biochemistry and a few graduate students. It uses a problem-based format. The problem, Plants versus animals in the dining hall, deals with amino acid metabolism and takes about 2 weeks to complete for the 15-20 students who work in groups of three or four students without a tutor-facilitator. The nature of the problem is such that it could be used or adapted for introductory biochemistry courses.The structure of this five-stage problem differs from many published in this journal in that it is written in the form of a story intended to engage undergraduate students. It involves a cogent, real-world situation that American college students certainly recognize. It requires them to analyze experimental data, make decisions, and locate information in the library or elsewhere. Although students who work on this problem will examine some amino acid pathways in depth, the objectives are to have them integrate multiple pathways and develop a broad view with detailed knowledge in a few areas, rather than memorize pathways. Among the many topics students will address while working on this problem are the following: As presented here, a number of citations appear in the text for readers to locate literature sources on these topics quickly. Normally, students do not receive these citations, because they need to become proficient in tracking down relevant information on their own.The problem consists of five stages presented successively. After reading the first, students typically discuss a variety of personal dietary experiences related to the problem and quickly realize there are many learning issues they need to address. Using textbooks available in the classroom, they answer some of their q...

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Study of Microbial Evolution through Loss of Biosynthetic Functions: Establishment of “Defective” Mutants

Cited by 144 publications

References 11 publications

Bacterial growth inhibition by overproduction of protein

Bacterial growth inhibition by overproduction of protein

Metabolic cross-feeding via intercellular nanotubes among bacteria

Plants versus animals in the dining hall: A problem‐based learning problem

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