کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10755238 1050370 2014 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
SecAAA trimer is fully functional as SecAA dimer in the membrane: Existence of higher oligomers?
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
SecAAA trimer is fully functional as SecAA dimer in the membrane: Existence of higher oligomers?
چکیده انگلیسی
SecA is an essential ATPase in bacterial Sec-dependent protein translocation pathway, and equilibrates between monomers and dimers in solution. The question of whether SecA functions as monomers or dimers in membranes during the protein translocation is controversial. We previously constructed a tail-to-head SecAA tandem dimer, and showed it is fully functional by complementation in vivo and protein translocation in vitro, indicating that SecA can function at least as a dimer in the membrane without dissociating into monomers. In this study, we further constructed genetically a tail-to-head SecAAA trimer, which is functional in complementing a temperature-sensitive secA mutant. The purified SecAAA trimer per protomer is fully active as SecAA tandem dimers in ATPase activity, in protein translocation in vitro and in ion channel activities in the oocytes. With these functional tail-to-head trimer SecAAA and tandem SecAA, we examined their surface topology in the presence of liposomes using AFM. As expected, the soluble SecAAA without lipids are larger than SecAA. However, the ring/pore structures of SecAAA trimers were, surprisingly, almost identical to the SecA 2-monomers and SecAA dimers, raising the intriguing possibility that the SecA may exist and function as hexamer ring-structures in membranes. Cross-linking with formaldehyde showed that SecA, SecAA and SecAAA could form larger oligomers, including the hexamers. The molecular modeling simulation shows that both tail-to-head and tail-to-tail hexamers in the membranes are possible.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochemical and Biophysical Research Communications - Volume 447, Issue 2, 2 May 2014, Pages 250-254
نویسندگان
, , , , , , ,