Analysis of the membrane interactive potential of the Escherichia coli PBP6b C-terminus

Escherichia coli low molecular weight penicillin binding proteins include PBP4,5,6 and recently PBP6b. PBP5 and PBP6 have been shown to possess C-terminal amphiphilic helical anchors. PBP4 has been shown to have the potential to interact at the membrane interface but the protein appears to bind via a different mechanism to PBP5 and PBP6. It has been suggested that since PBP6b has a high homology with PBP6 it also binds via an amphiphilic alpha helix. Here helical wheel, hydrophobic moment and DWIH analysis are used to show that the C-terminus of PBP6b does not resemble the anchor regions of the PBP5 and 6 but may stabilize membrane binding using a mechanism similar to that of PBP4.