NalP: Difference between revisions

The Translocator Domain for the Autotransporter NaIP within Neisseria meningitidis provides a novel protein pore that contains an alpha helix running axially through its hydrophobic center. Classically many outer membrane pores contain a 12 member beta barrel which is able to allow for different conditions than the peptidoglycan layer that would typically stop many types of proteins and ions from passing through. This alpha helix blocks the pore from being totally open and allows for more regulation of what enters and leaves the cell.

[[Image: Loop Structures.jpg | thumb | alt=text | Picture 1]]

Interesting questions were raised on how the alpha helix in the center if the beta barrel effected the mechanism of protein transportation out of the cell. The first step into understanding what shapes of proteins can move though the pore was figured by trying to move a disulfide bind through the pore. This was unsuccessful and led to part of the understanding that the only way that proteins can move though this pore was by being completely unfolded. Yet once inside of the extracellular material the protein much be folded. Knowing these tow crucial pieces of data it was clear that as the protein passes through the pore it is folded, and due to the c-terminal end's placement on the periplasm side of the pore it was highly unlikely that was the participating portion that effected the change in conformation of the protein as it passes through. Oppositely the n-terminal side of the pore lies on the alpha helix facing the extracellular matter placing it in prime location the change the conformation of the passing protein. Another possible place where interaction could occur between the passing protein and the pore would be at a large hairpin loop that is on the extracellular side of the pore. This would also provide a prime placement for initiation of protein folding.