Difference between revisions of "Part:BBa K208002"

Revision as of 16:18, 22 October 2009

Gene III Signal Peptide - Silver Fusion Compatible

This is a Silver-fusion compatible BioBrick part that can be attached to other proteins to target those proteins for export out of the cytoplasm. The GeneIII sequence targets unfolded proteins to the Sec-dependent pathway of Type II secretion.

Usage and Biology

Signal peptides consist of about 15-30 amino acids and are generally required to direct a secretory protein to the translocons of the cytoplasmic membrane (Pugsley, 1993; Choi, 2004; Luirink, 2004). Despite overall sequence variability, structural similarities exist between different signal peptides, including a positively-charged 2-10 amino acid N-region, a hydrophobic core H-region, and a neutral C-domain of about 6 residues (Pugsley, 1993; Molhoj, 2004). The C-domain conforms to the -3, -1 rule in which amino acids with short and neutral side-chains, such as alanine, are required in positions -3 and -1 of the sequence (Choi, 2004; von Heijne, 1986). A signal peptidase interacts with a cleavage recognition site within the C-domain to release the protein into the periplasmic space (Luiritz, 2004; Choi, 2004). Once in the periplasm, secretion into the extracellular media can occur via the action of a secreton, or by chemical or enzymatic methods.

In the Sec pathway, SecA is attached peripherally to the inner membrane and drives peptide translocation through ATPase activity (van der Does, 2004). Integral membrane proteins SecY and SecE form the core of the Sec translocon, and SecG interacts with this core to form a multimeric protein complex, SecYEG (Veenendaal, 2004). This complex functions as a protein-conducting channel for both post-translational and co-translational protein export (Luirink, 2004; Veenendaal, 2004). Interestingly, the SecYEG translocon can be found in all domains of life, reiterating the prevalence and importance of this mechanism for protein export (Cao, 2002).

Sequence and Features