TY - JOUR
T1 - Oligomeric structure of Colicin la channel in lipid bilayer membranes
AU - Greig, Sarah L.
AU - Radjainia, Mazdak
AU - Mitra, Alok K
PY - 2009/6/12
Y1 - 2009/6/12
N2 - Colicin Ia is a soluble, harpoon-shaped bacteriocin which translocates across the periplasmic space of sensitive Escherichia coli cell by parasitizing an outer membrane receptor and forms voltage-gated ion channels in the inner membrane. This process leads to cell death, which has been thought to be caused by a single colicin Ia molecule. To directly visualize the three-dimensional structure of the channel, we generated two-dimensional crystals of colicin Ia inserted in lipid-bilayer membranes and determined a ∼17 Å three-dimensional model by electron crystallography. Supported by velocity sedimentation, chemical cross-linking and single-particle image analysis, the three-dimensional structure is a crown-shaped oligomer enclosing a ∼35 Å-wide extrabilayer vestibule. Our study suggests that lipid insertion instigates a global conformational change in colicin Ia and that more than one molecule participates in the channel architecture with the vestibule, possibly facilitating the known large scale peptide translocation upon channel opening.
AB - Colicin Ia is a soluble, harpoon-shaped bacteriocin which translocates across the periplasmic space of sensitive Escherichia coli cell by parasitizing an outer membrane receptor and forms voltage-gated ion channels in the inner membrane. This process leads to cell death, which has been thought to be caused by a single colicin Ia molecule. To directly visualize the three-dimensional structure of the channel, we generated two-dimensional crystals of colicin Ia inserted in lipid-bilayer membranes and determined a ∼17 Å three-dimensional model by electron crystallography. Supported by velocity sedimentation, chemical cross-linking and single-particle image analysis, the three-dimensional structure is a crown-shaped oligomer enclosing a ∼35 Å-wide extrabilayer vestibule. Our study suggests that lipid insertion instigates a global conformational change in colicin Ia and that more than one molecule participates in the channel architecture with the vestibule, possibly facilitating the known large scale peptide translocation upon channel opening.
UR - http://www.scopus.com/inward/record.url?scp=67650249137&partnerID=8YFLogxK
U2 - 10.1074/jbc.M900292200
DO - 10.1074/jbc.M900292200
M3 - Article
C2 - 19357078
AN - SCOPUS:67650249137
VL - 284
SP - 16126
EP - 16134
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 1083-351X
IS - 24
ER -