1. Can the Sec pathway be used to export essentially any protein? That is, if you fused a Sec-leader sequence to any peptides coding sequence, could you get that protein exported into the periplasm? Why or why not? Can you cite evidence from the text to support your answer?
2. Where does the energy come from for translocation with the SecB/SecA system versus the SRP system?
3. Which gram-negative secretion systems do not
directly rely on the Sec system to get the secreted protein outside of the
cytoplasm?
4. What motif is common to all of the proteins that secrete proteins through the outer membrane?
5. Which one of the terminal secretion systems would be most useful to researchers studying mammalian
cell biology (not necessarily protein secretion)? Why?
6. If you wanted to design a plasmid vector to enable people
get their favorite protein secreted by E. coli, even though it wasn't normally a
secreted protein, which of the 6 systems would you choose? Why? Keep in
mind that the standard laboratory strain of E. coli K-12 does not possess any of
these 6 systems.
7. How does the fate of proteins secreted by
the sortase system of gram-positive bacteria differ from that of proteins
secreted by gram-negative bacteria?