An essential amino acid residue in the protein translocation channel revealed by targeted random mutagenesis of SecY
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Edited by William T. Wickner, Dartmouth Medical School, Hanover, NH, and approved February 21, 2001 (received for review December 27, 2000)
Abstract
The SecY/Sec61α family of membrane proteins are the central subunits of the putative protein translocation channel. We introduced random mutations into a segment of Escherichia coli SecY within its cytoplasmic domain 5, which was shown previously to be important for the SecA-dependent translocation activity. Mutations were classified into those retaining function and those gaining a dominant-interfering ability caused by a loss of function. These analyses showed that Arg-357, Pro-358, Gly-359, and Thr-362 are functionally important; Arg-357, conserved in almost all organisms, was identified as an indispensable residue.
Footnotes
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↵ * To whom reprint requests should be addressed. E-mail: kito{at}virus.kyoto-u.ac.jp.
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This paper was submitted directly (Track II) to the PNAS office.
- Abbreviation:
- MBP,
- maltose-binding protein
- Copyright © 2001, The National Academy of Sciences
