Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
STEM Talent Event

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 16 June 1967:
Vol. 156. no. 3781, pp. 1451 - 1455
DOI: 10.1126/science.156.3781.1451
Prev | Table of Contents | Next

Articles

Selective Release of Enzymes from Bacteria

Leon A. Heppel 1

1 National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland 20014

A group of hydrolytic enzymes, including phosphatases and nucleases, is selectively released from E. coli and certain other Gram-negative bacteria by a process designated as osmotic shock. This procedure involves exposure of the cells to ethylenediaminetetraacetate (EDTA) in 0.5 molar sucrose followed by a sudden osmotic transition to cold, dilute MgCl2. Osmotic shock also results in an alteration of the permeability barrier of the bacterial cell and a depletion of the pool of acid-soluble nucleotides, but there is no loss of viability. On being restored to growth medium, the shocked cells recover after a lag period. Formation of spheroplasts by treatment with EDTA and lysozyme leads to selective release of the same group of enzymes.

We believe that the selectively released enzymes are confined in a region between the bacterial cell wall and the cytoplasmic membrane. Histochemical studies indicate such a localization. Further, the enzyme activities are measurable with intact cells, even when the substrate is a nucleotide, to which whole cells are impermeable. Another piece of evidence concerns a mutant E. coli with a defective cell wall. In contrast to normal bacteria, this organism loses one of these enzymes into the medium in the course of growth.

After osmotic shock, the bacteria show reduced uptake of sulfate,betagalactosides, galactose, and certain amino acids. Furthermore, the shock treatment causes the release of nondialyzable factors able to bind sulfate, galactose, and the same amino acids. A possible interpretation of these observations is the following: the binding proteins occupy sites near the bacterial surface, and they may be components of active transport systems responsible for the concentrative uptake of these nutrients.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Periplasmic Protein HdeA Exhibits Chaperone-like Activity Exclusively within Stomach pH Range by Transforming into Disordered Conformation.
W. Hong, W. Jiao, J. Hu, J. Zhang, C. Liu, X. Fu, D. Shen, B. Xia, and Z. Chang (2005)
J. Biol. Chem. 280, 27029-27034
   Abstract »    Full Text »    PDF »
Regulation of Streptococcus gordonii sspB by the sspA Gene Product.
A. El-Sabaeny, D. R. Demuth, and R. J. Lamont (2001)
Infect. Immun. 69, 6520-6522
   Abstract »    Full Text »    PDF »
Thioredoxin-linked ``Thiol Peroxidase'' from Periplasmic Space of Escherichia coli.
M.-K. Cha, H.-K. Kim, and I.-H. Kim (1995)
J. Biol. Chem. 270, 28635-28641
   Abstract »    Full Text »    PDF »
Cellular Site of Glucocorticoid-Receptor Complex Formation.
B. B. Levinson, J. D. Baxter, G. G. Rousseau, and G. M. Tomkins (1972)
Science 175, 189-190
   Abstract »    PDF »
Cellular Localization of Leucine-Binding Protein from Escherichia coli.
P. K. Nakane, G. E. Nichoalds, and D. L. Oxender (1968)
Science 161, 182
   Abstract »    PDF »
Osmotic Pools in Escherichia coli.
D. Rogers (1968)
Science 159, 531-532
   Abstract »    PDF »


ADVERTISEMENT
Click Me!

ADVERTISEMENT
Click Me!

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)