tailieunhanh - Báo cáo khoa học: Membrane binding of SRP pathway components in the halophilic archaea Haloferax volcanii

Across evolution, the signal recognition particle pathway targets extra-cytoplasmic proteins to membranous trans-location sites. Whereas the pathway has been extensively studied in Eukarya and Bacteria, little is known of this sys-tem in Archaea. In the following, membrane association of FtsY, the prokaryal signal recognition particle receptor, and SRP54, a central component of the signal recognition par-ticle, was addressed in the halophilic archaea Haloferax volcanii. | Eur. J. Biochem. 271 1382-1390 2004 FEBS 2004 doi Membrane binding of SRP pathway components in the halophilic archaea Haloferax volcanii Tovit Lichi Gabriela Ring and Jerry Eichler Department of Life Sciences Ben Gurion University of the Negev Beersheva Israel Across evolution the signal recognition particle pathway targets extra-cytoplasmic proteins to membranous translocation sites. Whereas the pathway has been extensively studied in Eukarya and Bacteria little is known of this system in Archaea. In the following membrane association of FtsY the prokaryal signal recognition particle receptor and SRP54 a central component of the signal recognition particle was addressed in the halophilic archaea Haloferax volcanii. Purified H. volcanii FtsY the FtsY C-terminal GTP-binding domain NG domain or SRP54 were combined separately or in different combinations with H. vol-canii inverted membrane vesicles and examined by gradient floatation to differentiate between soluble and membranebound protein. Such studies revealed that both FtsY and the FtsY NG domain bound to H. volcanii vesicles in a manner unaffected by proteolytic pretreatment of the membranes implying that in Archaea FtsY association is mediated through the membrane lipids. Indeed membrane association of FtsY was also detected in intact H. volcanii cells. The contribution of the NG domain to FtsY binding in halophilic archaea may be considerable given the low number of basic charges found at the start of the N-terminal acidic domain of haloarchaeal FtsY proteins the region of the protein thought to mediate FtsY-membrane association in Bacteria . Moreover FtsY but not the NG domain was shown to mediate membrane association of H. volcanii SRP54 a protein that did not otherwise interact with the membrane. Keywords Archaea FtsY Haloferax volcanii protein targeting signal recognition particle. It is becoming increasingly clear that similarities exist not only in the .

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