Difference between revisions of "Part:BBa K208006"

Latest revision as of 00:50, 23 October 2009

HlyA Signal Peptide - Silver Fusion Compatible

The HlyA signal peptide is used to target proteins for secretion via the Type I secretion pathway of gram-negative bacteria. Unlike Type II signal peptides, fusion of the HlyA signal peptide to the target protein may result in transport of the protein from the cytoplasm to the extracellular medium in a single step. This particular BioBrick is Silver-fusion compatible and should be appended to the C-terminus of the target protein (unlike the Type II signal peptides that should be fused to the N-terminus).

Usage and Biology

Type I secretion is a single-step translocation of protein across both inner and outer membranes. (Binet, 1997). The constituents of this system include inner membrane proteins HlyB and HlyD, as well as the TolC outer membrane protein (Mergulhão, 2005; Desveax, 2004). These three proteins interact to form a channel that spans the periplasm (Mergulhão, 2005). Appending the last 42-60 amino acids of the HlyA protein C-terminus to the C-terminus of a recombinant protein targets the protein for secretion (Mergulhão, 2005; Gentschev, 2003; Hess, 1990). The HlyA signal sequence binds to the channel complex, resulting in ATP hydrolysis by HlyB to drive protein secretion (Gentschev, 2003). Proteins as large as 4000 amino acids can be secreted through the type I channel, which has an internal diameter of 3.5 nm and a length of 14 nm (Sapriel, 2003; Fernandez and de Lorenzo, 2001). Unlike in the Type II pathway, the signal peptides of Type I secretion remain attached to the protein after export out of the cytoplasm (Blight and Holland, 1994).

Sequence and Features