Hostname: page-component-7c8c6479df-8mjnm Total loading time: 0 Render date: 2024-03-27T15:52:57.822Z Has data issue: false hasContentIssue false

Fitness as a function of β-galactosidase activity in Escherichia coli

Published online by Cambridge University Press:  14 April 2009

Antony M. Dean
Affiliation:
Department of Genetics, Washington University School of Medicine, St Louis, MissouriUSA63110-1095
Daniel E. Dykhuizen
Affiliation:
Department of Genetics, Washington University School of Medicine, St Louis, MissouriUSA63110-1095
Daniel L. Hartl
Affiliation:
Department of Genetics, Washington University School of Medicine, St Louis, MissouriUSA63110-1095
Rights & Permissions [Opens in a new window]

Summary

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Chemostat cultures in which the limiting nutrient was lactose have been used to study the relative growth rate of Escherichia coli in relation to the enzyme activity of β-galactosidase. A novel genetic procedure was employed in order to obtain amino acid substitutions within the lacZ-encoded β-galactosidase that result in differences in enzyme activity too small to be detected by ordinary mutant screens. The cryptic substitutions were obtained as spontaneous revertants of nonsense mutations within the lacZ gene, and the enzymes differing from wild type were identified by means of polyacrylamide gel electrophoresis or thermal denaturation studies. The relation between enzyme activity and growth rate of these and other mutants supports a model of intermediary metabolism in which the flux of substrate through a metabolic pathway is represented by a concave function of the activity of any enzyme in the pathway. The consequence is that small differences in enzyme activity from wild type result in even smaller changes in fitness.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1986

References

Bradford, M. M. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry 72, 248254.CrossRefGoogle ScholarPubMed
Dykhuizen, D. E. & Davies, M. (1980). An experimental model: bacterial specialists and generalists competing in chemostats. Ecology 61, 5, 12131227.CrossRefGoogle Scholar
Dykhuizen, D. E. & Hartl, D. L. (1980). Selective neutrality of 6PGD allozymes in E. coli and the effects of genetic background. Genetics 96, 801817.CrossRefGoogle Scholar
Dykhuizen, D. E. & Hartl, D. L. (1983). Functional effects of PGI allozymes in E. coli. Genetics 105, 118.CrossRefGoogle Scholar
Flint, H. J., Tateson, R. W., Barthelmess, I. B., Porteous, D. J., Donachie, W. D. & Kacser, H. (1981). Control of flux in the arginine pathway of Neurospora crassa. Biochem. J. 200, 231246.CrossRefGoogle ScholarPubMed
Hall, B. G. (1982). Transgalactosylation activity of ebg β-galactosidase synthesizes allolactose from lactose. J. Bacteriology 105, 132140.CrossRefGoogle Scholar
Hall, B. G. (1984). The evolved β-galactosidase system of Escherichia coli. In Microorganisms as Model Systems for Studying Evolution (ed. Mortlock, R. P.), pp. 165185. New York: Plenum.CrossRefGoogle Scholar
Hartl, D. L. & Dykhuizen, D. E. (1981). Potential for selection among nearly neutral allozymes of 6-phosphogluconate dehydrogenase in Escherichia coli. Proceedings of the National Academy of Sciences of the United States of America 78, 63446348.CrossRefGoogle ScholarPubMed
Hartl, D. L., Dykhuizen, D. E. & Dean, A. (1985). Limits of adaption: the evolution of selective neutrality. Genetics 111, 655674.CrossRefGoogle ScholarPubMed
Heinrich, R. E. & Rapoport, S. M. (1983). The utility of mathematical models for the understanding of metabolic systems. Biochemical Society Transactions 11, 3135.CrossRefGoogle ScholarPubMed
Huber, R. E., Kurz, G. & Wallenfells, K. (1976). A quantitation of the factors which affect the hydrolase and transgalactosylase activities of β-galactosidase (E. coli) on lactose. Biochemistry 15, 19942001.CrossRefGoogle ScholarPubMed
Kacser, H. & Burns, J. A. (1973). The control of flux. Symposium of the Society for Experimental Biology 32, 65104.Google Scholar
Kacser, H. & Burns, J. A. (1979). Molecular democracy: who shares the controls? Biochemical Society Transactions 7, 11501160.CrossRefGoogle ScholarPubMed
Kacser, H. & Burns, J. A. (1981). The molecular basis of dominance. Genetics 97, 639666.CrossRefGoogle ScholarPubMed
Kacser, H. & Beeby, R. (1984). Evolution of catalytic proteins, or On the origin of enzyme species by means of natural selection. Molecular Evolution 20, 3851.CrossRefGoogle ScholarPubMed
Langridge, J. (1974). Mutation spectra and the neutrality of mutations. Australian Journal of Biological Sciences 27, 309319.CrossRefGoogle ScholarPubMed
Middleton, R. J. & Kacser, H. (1983). Enzyme variation, metabolic flux and fitness: alcohol dehydrogenase in Drosophila melanogaster. Genetics 105, 633650.CrossRefGoogle ScholarPubMed
Miller, J. H. (1972). Experiments in Molecular Genetics. New York: Cold Spring Harbor Laboratory.Google Scholar
Stokes, H. W., Betts, P. W. & Hall, B. G. (1985). Sequence of the ebgA gene of E. coli: comparison with the lacZ gene. Molecular Biology and Evolution 2, 469477.Google ScholarPubMed