TY - JOUR
T1 - Translocation of inserted foreign epitopes by a channel-forming protein
AU - Jakes, Karen S.
AU - Kienker, Paul K.
AU - Slatin, Stephen L.
AU - Finkelstein, Alan
PY - 1998/4/14
Y1 - 1998/4/14
N2 - Certain bacterial protein toxins are able to insert themselves into, and at least partially across, lipid bilayer membranes in the absence of any auxiliary proteins, by using unknown mechanisms to overcome the high energy harrier presented by the hydrophobic bilayer core. We have previously shown that one such toxin, colicin Ia, translocates a large, hydrophilic part of itself completely across a lipid bilayer in conjunction with the formation of an ion-conducting channel. To address the question of whether the colicin can translocate any arbitrary amino acid sequence, we have altered the translocated segment by inserting, singly, two different foreign epitopes. Colicins containing either epitope retain significant bactericidal activity and form channels of normal conductance in planar bilayers. Furthermore, antibodies added on the side of the bilayer opposite that to which the colicin was added interact specifically with the corresponding epitopes, producing an inhibition of channel closing. Thus, the inserted epitopes are translocated along with the rest of the segment, suggesting that a surprisingly small part of colicin Ia, located elsewhere in the molecule, acts as a nonspecific protein translocator.
AB - Certain bacterial protein toxins are able to insert themselves into, and at least partially across, lipid bilayer membranes in the absence of any auxiliary proteins, by using unknown mechanisms to overcome the high energy harrier presented by the hydrophobic bilayer core. We have previously shown that one such toxin, colicin Ia, translocates a large, hydrophilic part of itself completely across a lipid bilayer in conjunction with the formation of an ion-conducting channel. To address the question of whether the colicin can translocate any arbitrary amino acid sequence, we have altered the translocated segment by inserting, singly, two different foreign epitopes. Colicins containing either epitope retain significant bactericidal activity and form channels of normal conductance in planar bilayers. Furthermore, antibodies added on the side of the bilayer opposite that to which the colicin was added interact specifically with the corresponding epitopes, producing an inhibition of channel closing. Thus, the inserted epitopes are translocated along with the rest of the segment, suggesting that a surprisingly small part of colicin Ia, located elsewhere in the molecule, acts as a nonspecific protein translocator.
UR - http://www.scopus.com/inward/record.url?scp=0032516045&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032516045&partnerID=8YFLogxK
U2 - 10.1073/pnas.95.8.4321
DO - 10.1073/pnas.95.8.4321
M3 - Article
C2 - 9539735
AN - SCOPUS:0032516045
SN - 0027-8424
VL - 95
SP - 4321
EP - 4326
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 8
ER -