TY - JOUR
T1 - Channel properties of the translocator domain of the autotransporter Hbp of Escherichia coli
AU - Roussel-Jazede, V.
AU - van Gelder, P.
AU - Sijbrandi, R.
AU - Rutten, L.
AU - Otto, B.R.
AU - Luirink, J.
AU - Gros, P.
AU - Tommassen, J.
AU - van Ulsen, P.
N1 - 1464-5203 Roussel-Jazede, Virginie Van Gelder, Patrick Sijbrandi, Robert Rutten, Lucy Otto, Ben R Luirink, Joen Gros, Piet Tommassen, Jan Van Ulsen, Peter Journal Article Research Support, Non-U.S. Gov't England Mol Membr Biol. 2011 Apr;28(3):158-70. doi: 10.3109/09687688.2010.550328. Epub 2011 Feb 14.
PY - 2011
Y1 - 2011
N2 - Autotransporters produced by Gram-negative bacteria consist of an N-terminal signal sequence, a C-terminal translocator domain (TD), and a passenger domain in between. The TD facilitates the secretion of the passenger across the outer membrane. It generally consists of a channel-forming β-barrel that can be plugged by an α-helix that is formed by a polypeptide fragment immediately N-terminal to the barrel domain in the sequence. In this work, we characterized the TD of the hemoglobin protease Hbp of Escherichia coli by comparing its properties with the TDs of NalP of Neisseria meningitidis and IgA protease of Neisseria gonorrhoeae. All TDs were produced in inclusion bodies and folded in vitro. In the case of the TD of Hbp, this procedure resulted in autocatalytic intramolecular processing, which mimicked the in vivo processing. Liposome-swelling assays and planar lipid bilayer experiments revealed that the pore of the Hbp TD was largely obstructed. In contrast, an Hbp TD variant that lacked only one amino-acid residue from the N terminus showed the opening and closing of a channel comparable to what was reported for the TD of NalP. Additionally, the naturally processed helix contributed to the stability of the TD, as shown by chemical denaturation monitored by tryptophan fluorescence. Overall these results show that Hbp is processed by an autocatalytic intramolecular mechanism resulting in the stable docking of the α-helix in the barrel. In addition, we could show that the α-helix contributes to the stability of TDs. © 2011 Informa UK, Ltd.
AB - Autotransporters produced by Gram-negative bacteria consist of an N-terminal signal sequence, a C-terminal translocator domain (TD), and a passenger domain in between. The TD facilitates the secretion of the passenger across the outer membrane. It generally consists of a channel-forming β-barrel that can be plugged by an α-helix that is formed by a polypeptide fragment immediately N-terminal to the barrel domain in the sequence. In this work, we characterized the TD of the hemoglobin protease Hbp of Escherichia coli by comparing its properties with the TDs of NalP of Neisseria meningitidis and IgA protease of Neisseria gonorrhoeae. All TDs were produced in inclusion bodies and folded in vitro. In the case of the TD of Hbp, this procedure resulted in autocatalytic intramolecular processing, which mimicked the in vivo processing. Liposome-swelling assays and planar lipid bilayer experiments revealed that the pore of the Hbp TD was largely obstructed. In contrast, an Hbp TD variant that lacked only one amino-acid residue from the N terminus showed the opening and closing of a channel comparable to what was reported for the TD of NalP. Additionally, the naturally processed helix contributed to the stability of the TD, as shown by chemical denaturation monitored by tryptophan fluorescence. Overall these results show that Hbp is processed by an autocatalytic intramolecular mechanism resulting in the stable docking of the α-helix in the barrel. In addition, we could show that the α-helix contributes to the stability of TDs. © 2011 Informa UK, Ltd.
U2 - 10.3109/09687688.2010.550328
DO - 10.3109/09687688.2010.550328
M3 - Article
SN - 0968-7688
VL - 28
SP - 158
EP - 170
JO - Molecular Membrane Biology
JF - Molecular Membrane Biology
ER -