title: Phospholipids induce conformational changes of SecA to form membrane-specific domains: AFM structures and implication on protein-conducting channels.
abstract: SecA, an essential component of the Sec machinery, exists in a soluble and a membrane form in Escherichia coli. Previous studies have shown that the soluble SecA transforms into pore structures when it interacts with liposomes, and integrates into membranes containing SecYEG in two forms: SecAS and SecAM; the latter exemplified by two tryptic membrane-specific domains, an N-terminal domain (N39) and a middle M48 domain (M48). The formation of these lipid-specific domains was further investigated. The N39 and M48 domains are induced only when SecA interacts with anionic liposomes. Additionally, the N-terminus, not the C-terminus of SecA is required for inducing such conformational changes. Proteolytic treatment and sequence analyses showed that liposome-embedded SecA yields the same M48 and N39 domains as does the membrane-embedded SecA. Studies with chemical extraction and resistance to trypsin have also shown that these proteoliposome-embedded SecA fragments exhibit the same stability and characteristics as their membrane-embedded SecA equivalents. Furthermore, the cloned lipid-specific domains N39 and M48, but not N68 or C34, are able to form partial, but imperfect ring-like structures when they interact with phospholipids. These ring-like structures are characteristic of a SecA pore-structure, suggesting that these domains contribute part of the SecA-dependent protein-conducting channel. We, therefore, propose a model in which SecA alone is capable of forming a lipid-specific, asymmetric dimer that is able to function as a viable protein-conducting channel in the membrane, without any requirement for SecYEG.
authors: Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia, United States of America.
authors: Zhipeng
authors: Z
authors: You
authors: Meijiang
authors: M
authors: Liao
authors: Hao
authors: H
authors: Zhang
authors: Hsiuchin
authors: H
authors: Yang
authors: Xijian
authors: X
authors: Pan
authors: John E
authors: JE
authors: Houghton
authors: Sen-Fang
authors: SF
authors: Sui
authors: Phang C
authors: PC
authors: Tai
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D059748:Proteolysis; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D012995:Solubility
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D008081:Liposomes; D026901:Membrane Transport Proteins; D010743:Phospholipids; D000069816:SEC Translocation Channels; D010447:Peptide Hydrolases; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins
references: J Biol Chem. 1991 Dec 25;266(36):24420-7
references: 1837021
references: J Biol Chem. 2000 Aug 11;275(32):25000-7
references: 10835419
references: Cell. 1995 Dec 29;83(7):1171-81
references: 8548804
references: Biochemistry. 1998 Jan 6;37(1):201-10
references: 9425040
references: J Bacteriol. 2008 May;190(10):3505-25
references: 18296516
references: J Bacteriol. 1998 Nov;180(21):5776-9
references: 9791133
references: J Bacteriol. 1988 Aug;170(8):3404-14
references: 2841285
references: Methods Cell Biol. 1991;34:167-87
references: 1943799
references: J Bacteriol. 2008 Feb;190(4):1413-8
references: 18065528
references: Cell. 1988 Nov 18;55(4):683-92
references: 2846186
references: J Bacteriol. 1997 Sep;179(18):5699-704
references: 9294424
references: EMBO J. 2003 Sep 1;22(17):4375-84
references: 12941690
references: J Membr Biol. 2006;214(2):103-13
references: 17530158
references: Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):4221-6
references: 12642659
references: Cell. 1982 Aug;30(1):311-9
references: 6751561
references: Sci China Life Sci. 2010 Sep;53(9):1049-56
references: 21104364
references: J Biol Chem. 2000 Jan 28;275(4):2472-8
references: 10644701
references: Cell. 1994 Sep 9;78(5):835-43
references: 8087850
references: J Biol Chem. 1996 Dec 6;271(49):31580-4
references: 8940175
references: Proc Natl Acad Sci U S A. 1990 Mar;87(5):1960-4
references: 2408048
references: Biochemistry. 1993 Dec 7;32(48):13190-7
references: 8241173
references: Biochemistry. 1992 Feb 4;31(4):1119-24
references: 1531180
references: J Biol Chem. 1995 Aug 25;270(34):20106-11
references: 7650029
references: Biochemistry. 2003 Nov 25;42(46):13468-75
references: 14621992
references: J Biol Chem. 1998 Aug 21;273(34):21675-81
references: 9705302
references: J Struct Biol. 2007 Jul;159(1):149-53
references: 17419072
references: Cell. 1981 Sep;25(3):765-72
references: 7026050
references: J Biol Chem. 1991 Apr 5;266(10):6600-6
references: 1826108
references: J Bacteriol. 1998 Feb;180(3):527-37
references: 9457854
references: Nature. 1987 Jul 9-15;328(6126):164-6
references: 3299104
references: J Membr Biol. 1998 Mar 1;162(1):1-7
references: 9516232
references: J Biol Chem. 1992 Jul 25;267(21):15184-92
references: 1386084
references: J Biol Chem. 1997 May 23;272(21):13660-5
references: 9153216
references: J Bacteriol. 1995 Nov;177(21):6153-9
references: 7592380
references: Mol Microbiol. 1993 Nov;10(3):483-97
references: 7968527
references: J Bacteriol. 1997 Dec;179(23):7386-93
references: 9393703
references: J Bacteriol. 2006 Jan;188(1):335-8
references: 16352850
references: Cell. 1996 Apr 5;85(1):71-81
references: 8620539
references: Biochem Biophys Res Commun. 2013 Feb 15;431(3):388-92
references: 23337498
references: J Biol Chem. 1975 Feb 25;250(4):1383-92
references: 163252
references: Biochemistry. 1998 Sep 1;37(35):12261-8
references: 9724540
references: Mol Microbiol. 1996 Nov;22(4):619-29
references: 8951810
references: J Biol Chem. 1997 Apr 25;272(17):11302-6
references: 9111035
references: J Biol Chem. 1997 Sep 12;272(37):23239-46
references: 9287332
references: EMBO J. 1989 Mar;8(3):961-6
references: 2542029
references: Proc Natl Acad Sci U S A. 1997 May 27;94(11):5574-81
references: 9159114
references: J Biol Chem. 1991 Mar 25;266(9):5827-33
references: 1826005
references: PLoS One. 2011 Jan 27;6(1):e16498
references: 21304597
references: J Biol Chem. 1996 Nov 22;271(47):29698-706
references: 8939903
references: J Biochem. 1998 Jul;124(1):122-9
references: 9644254
references: Biochim Biophys Acta. 2004 Nov 11;1694(1-3):67-80
references: 15546658
references: J Biol Chem. 1990 Mar 5;265(7):4048-53
references: 2105958
references: J Membr Biol. 2012 Nov;245(11):747-57
references: 22854753
references: Proc Natl Acad Sci U S A. 2005 May 24;102(21):7511-6
references: 15897468
references: Mol Microbiol. 1998 Sep;29(5):1179-90
references: 9767586
references: Biochemistry. 2001 Feb 13;40(6):1835-43
references: 11327846
references: Proc Natl Acad Sci U S A. 1993 Oct 1;90(19):9011-5
references: 8415645
references: J Biol Chem. 1995 Apr 7;270(14):7902-7
references: 7713885
references: J Bacteriol. 1997 Feb;179(3):689-96
references: 9006022
references: J Biol Chem. 2004 Apr 2;279(14):13769-77
references: 14722060
references: Mol Microbiol. 1999 Dec;34(5):1133-45
references: 10594836
references: J Biol Chem. 2000 Apr 7;275(14):10154-9
references: 10744698
references: J Biol Chem. 1996 May 24;271(21):12394-400
references: 8647843
references: J Biol Chem. 2000 Oct 27;275(43):33209-12
references: 10982786
references: Mol Microbiol. 2000 Jul;37(2):226-38
references: 10931320
references: Biochem Biophys Res Commun. 1991 Jan 15;174(1):211-6
references: 1824919
references: Proc Natl Acad Sci U S A. 1985 Jul;82(13):4384-8
references: 2861605
references: EMBO J. 1997 May 1;16(9):2188-96
references: 9171334
references: J Biol Chem. 1990 May 25;265(15):8760-5
references: 2160468
references: J Mol Biol. 2007 Mar 9;366(5):1545-57
references: 17229438
references: J Biol Chem. 2011 Dec 30;286(52):44702-9
references: 22033925
references: J Biol Chem. 1991 Dec 25;266(36):24596-600
references: 1837025