par Goulart, Carolina Lage;Bisch, Paulo Mascarello 
;Von Krüger, Wanda M A;Homblé, Fabrice
Référence Biochimica et biophysica acta. Biomembranes, 1848, 2, page (680-687)
Publication Publié, 2015
;Von Krüger, Wanda M A;Homblé, Fabrice Référence Biochimica et biophysica acta. Biomembranes, 1848, 2, page (680-687)
Publication Publié, 2015
Article révisé par les pairs
| Résumé : | A putative porin function has been assigned to VCA1008 of Vibrio cholerae. Its coding gene, vca1008, is expressed upon colonization of the small intestine in infant mice and human volunteers, and is essential for infection. In vitro, vca1008 is expressed under inorganic phosphate limitation and, in this condition, VCA1008 is the major outer membrane protein of the bacterium. Here, we provide the first functional characterization of VCA1008 reconstituted into planar lipid bilayers. Our main findings were: 1) VCA1008 forms an ion channel that, at high voltage (~ ± 100mV), presents a voltage-dependent activity and displays closures typical of trimeric porins, with a conductance of 4.28 ± 0.04 nS (n = 164) in 1M KCl; 2) It has a preferred selectivity for anions over cations; 3) Its conductance saturates with increasing inorganic phosphate concentration, suggesting VCA1008 contains binding site(s) for this anion; 4) Its ion selectivity is controlled by both fixed charged residues within the channel and diffusion along the pore; 5) Partitioning of poly (ethylene glycol)s (PEGs) of different molecular mass suggests that VCA1008 channel has a pore exclusion limit of 0.9 nm. |
