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Published November 29, 1991 | public
Journal Article

The N-end rule in bacteria


The N-end rule relates the in vivo half-life of a protein to the identity of its amino-terminal residue. Distinct versions of the N-end rule operate in all eukaryotes examined. It is shown that the bacterium Escherichia coli also has the N-end rule pathway. Amino-terminal arginine, lysine, leucine, phenylalanine, tyrosine, and tryptophan confer 2-minute half-lives on a test protein; the other amino-terminal residues confer greater than 10-hour half-lives on the same protein. Amino-terminal arginine and lysine are secondary destabilizing residues in E. coli because their activity depends on their conjugation to the primary destabilizing residues leucine or phenylalanine by leucine, phenylalanine-transfer RNA-protein transferase. The adenosine triphosphate-dependent protease Clp (Ti) is required for the degradation of N-end rule substrates in E. coli.

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© 1991 American Association for the Advancement of Science. 6 June 1991; accepted 9 September 1991. We thank B. Wanner for the BW13711 strain; D. Parcel, R. Sauer, W. Waker, C. Gross, and B. Bachman for other E. coli strains; G. Walker and members of his laboratory for advice; J. Essigman for making PhosphorImager available to us; and B. Doran for secretarial assistance. Supported by NIH grant DK39520 and GM31530 (to A.V.). T.E.S. is a Merck Fellow of the Helen Hay Whitney Foundation.

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