Role of membrane potential in protein folding and domain formation during secretion in escherichia coli

✍ Scribed by Bruce R. Copeland; Robert Landick; Penelope M. Nazos; Dale L. Oxender

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 772 KB
• Volume: 24
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240240405

✦ Synopsis

The synthesis and processing of the periplasmic components of the leucine transport system of E coli have been studied to determine the role played by transmembrane potential in protein secretion. Both the leucine-isoleucine-valine binding protein and the leucine-specific binding protein are synthesized as precursors with 23 amino acid N-terminal leader sequences. The processing of these precursors is sensitive to the transmembrane potential. Since the amino acid sequence and the crystal structure have been determined for the leucine-isoleucine-valine binding protein, it and the closely related leucine-specific binding protein represent convenient models in which to examine the mechanism of protein secretion in E coli. A model for secretion has been proposed, suggesting a role for transmembrane potential. In this model, the N-terminal amino acid sequence of the precursor is assumed to form a hairpin of two helices. The membrane potential may orient this structure to make it accessible to processing. In addition, the model suggests that a negatively charged, folded domain of the secretory protein may electrophorese toward the trans-positive side of the membrane, thus providing an additional role for the transmembrane potential.