The McrB restriction system in Escherichia coli K12 causes sequence-specific recognition and inactivation of DNA containing 5-methylcytosine residues. We have previously located the mcrB gene near hsdS at 99 min on the E. coli chromosome and demonstrated that it encodes a 51 kDa polypeptide required
Requirement of the SecB chaperone for export of a non-secretory polypeptide in Escherichia coli
β Scribed by Maclntyre, Sheila ;Mutschler, Bettina ;Henning, Ulf
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 645 KB
- Volume
- 227
- Category
- Article
- ISSN
- 0026-8925
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β¦ Synopsis
The SecB protein of Escherichia coli is a cytosolic component of the export machinery which can prevent some precursors from prematurely folding into export-incompatible conformations by binding to the newly synthesised polypeptide. The feature(s) of target proteins recognised by SecB, however, are unclear and have been a matter of controversy. Also, it has not been asked if binding of SecB is specific for secretory proteins. We demonstrate here that a non-secretory polypeptide, a fragment of a tail fiber protein of phage T4, fused to the signal peptide of the outer membrane protein OmpA has a very strong SecB requirement for export and that the signal peptide itself cannot, at least not alone, be responsible for this action of SecB. The data reported, together with those of the literature, suggest that SecB recognizes the polypeptide backbone of the target protein.
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