Protein transport across membranes: Comparison between lysine and guanidinium-rich carriers.
The mechanism(s) by which certain small peptides and peptide mimics carry large cargoes across membranes through exclusively non-covalent interactions has been difficult to resolve. Here, we use the droplet-interface bilayer as a platform to characterize distinct mechanistic differences between two such carriers: Pep-1 and a guanidinium-rich peptide mimic we call D9. While both Pep-1 and D9 can carry an enzyme, horseradish peroxidase (HRP) across a lipid bilayer, we found that they do so by different mechanisms. Specifically, Pep-1 requires voltage or membrane asymmetry while D9 does not. In addition, D9 can facilitate HRP transport without pre-forming a complex with HRP. By contrast, complex formation is required by Pep-1. Both carriers are capable of forming pores in membranes but our data hints that these pores are not responsible for cargo transport. Overall, D9 appears to be a more potent and versatile transporter when compared with Pep-1 because D9 does not require an applied voltage or other forces to drive transport. Thus, D9 might be used to deliver cargo across membranes under conditions where Pep-1 would be ineffective.
Department of Chemistry, University of Massachusetts, 710 North Pleasant St, Amherst, MA 01003, USA.
Max
M
Lein
Departments of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA.
Brittany M
BM
deRonde
Departments of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA.
Federica
F
Sgolastra
Departments of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003, USA; Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA.
Gregory N
GN
Tew
Department of Chemistry, University of Massachusetts, 710 North Pleasant St, Amherst, MA 01003, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA.
Matthew A
MA
Holden
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D003543:Cysteamine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008564:Membrane Potentials; D008954:Models, Biological; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport
D002352:Carrier Proteins; D008051:Lipid Bilayers; C503924:Pep-1 peptide; D010455:Peptides; D003543:Cysteamine; D006735:Horseradish Peroxidase; D019791:Guanidine
Arginine-rich peptide; Droplet-interface bilayer (DIB); Guanidine; Membrane translocation; Pep-1; Protein transduction domain mimic (PTDM)