title: Identification and characterization of a novel porin family highlights a major difference in the outer membrane of chlamydial symbionts and pathogens.
abstract: The Chlamydiae constitute an evolutionary well separated group of intracellular bacteria comprising important pathogens of humans as well as symbionts of protozoa. The amoeba symbiont Protochlamydia amoebophila lacks a homologue of the most abundant outer membrane protein of the Chlamydiaceae, the major outer membrane protein MOMP, highlighting a major difference between environmental chlamydiae and their pathogenic counterparts. We recently identified a novel family of putative porins encoded in the genome of P. amoebophila by in silico analysis. Two of these Protochlamydiaouter membrane proteins, PomS (pc1489) and PomT (pc1077), are highly abundant in outer membrane preparations of this organism. Here we show that all four members of this putative porin family are toxic when expressed in the heterologous host Escherichia coli. Immunofluorescence analysis using antibodies against heterologously expressed PomT and PomS purified directly from elementary bodies, respectively, demonstrated the location of both proteins in the outer membrane of P. amoebophila. The location of the most abundant protein PomS was further confirmed by immuno-transmission electron microscopy. We could show that pomS is transcribed, and the corresponding protein is present in the outer membrane throughout the complete developmental cycle, suggesting an essential role for P. amoebophila. Lipid bilayer measurements demonstrated that PomS functions as a porin with anion-selectivity and a pore size similar to the Chlamydiaceae MOMP. Taken together, our results suggest that PomS, possibly in concert with PomT and other members of this porin family, is the functional equivalent of MOMP in P. amoebophila. This work contributes to our understanding of the adaptations of symbiotic and pathogenic chlamydiae to their different eukaryotic hosts.
authors: Department of Microbial Ecology, University of Vienna, Vienna, Austria.
authors: Karin
authors: K
authors: Aistleitner
authors: Christian
authors: C
authors: Heinz
authors: Alexandra
authors: A
authors: Hörmann
authors: Eva
authors: E
authors: Heinz
authors: Jacqueline
authors: J
authors: Montanaro
authors: Frederik
authors: F
authors: Schulz
authors: Elke
authors: E
authors: Maier
authors: Peter
authors: P
authors: Pichler
authors: Roland
authors: R
authors: Benz
authors: Matthias
authors: M
authors: Horn
mesh_terms: D000656:Amoeba / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002693:Chlamydiaceae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D008051:Lipid Bilayers / Q000378:metabolism; D018272:Porins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D013559:Symbiosis; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D008051:Lipid Bilayers; D018272:Porins
references: J Bacteriol. 1995 Feb;177(4):877-82
references: 7532170
references: Mol Microbiol. 1995 Feb;15(4):607-16
references: 7783633
references: Mol Biol Evol. 2011 Dec;28(12):3253-70
references: 21690563
references: J Bacteriol. 1992 Jan;174(2):619-22
references: 1729251
references: Mol Microbiol. 1992 May;6(9):1087-94
references: 1588812
references: J Biol Chem. 1988 Jan 25;263(3):1182-7
references: 2447086
references: Adv Biochem Eng Biotechnol. 2004;89:73-92
references: 15217156
references: J Bacteriol. 2001 Apr;183(8):2686-90
references: 11274132
references: Clin Microbiol Infect. 2009 Jan;15(1):4-10
references: 19220334
references: Science. 2004 Apr 30;304(5671):728-30
references: 15073324
references: J Comp Pathol. 2003 May;128(4):217-44
references: 12834606
references: Infect Immun. 1990 Sep;58(9):3101-8
references: 2387636
references: PLoS One. 2010 May 28;5(5):e10890
references: 20531937
references: Infect Immun. 1984 May;44(2):479-85
references: 6715046
references: Nucleic Acids Res. 2007 Jul;35(Web Server issue):W71-4
references: 17485472
references: J Proteome Res. 2006 Sep;5(9):2339-47
references: 16944946
references: Infect Immun. 1981 Mar;31(3):1161-76
references: 7228399
references: Microbes Infect. 2005 Mar;7(3):410-20
references: 15784185
references: J Immunol. 1982 Mar;128(3):1083-9
references: 7035557
references: J Bacteriol. 1985 May;162(2):722-7
references: 2580824
references: Proc Natl Acad Sci U S A. 2007 Jul 3;104(27):11430-5
references: 17592133
references: Proc Natl Acad Sci U S A. 2003 Jul 8;100(14):8478-83
references: 12815105
references: Anal Chem. 2010 Oct 15;82(20):8696-702
references: 20845935
references: Nucleic Acids Res. 2004 Jul 1;32(Web Server issue):W400-4
references: 15215419
references: FEBS Lett. 1999 Feb 19;445(1):192-6
references: 10069399
references: J Bacteriol. 1977 Aug;131(2):623-30
references: 328490
references: Infect Immun. 1997 Aug;65(8):3361-9
references: 9234798
references: Infect Immun. 1998 Nov;66(11):5202-7
references: 9784523
references: Infect Immun. 1991 Aug;59(8):2843-5
references: 1713202
references: Clin Microbiol Infect. 2009 Jan;15(1):29-35
references: 19220337
references: Nat Methods. 2011 Sep 29;8(10):785-6
references: 21959131
references: Can J Microbiol. 2007 Apr;53(4):526-32
references: 17612609
references: Infect Immun. 1987 Jan;55(1):162-8
references: 3793227
references: Annu Rev Microbiol. 2008;62:113-31
references: 18473699
references: J Mol Biol. 1996 Jul 19;260(3):289-98
references: 8757792
references: Infect Immun. 1984 Nov;46(2):484-8
references: 6209221
references: Trends Microbiol. 2006 Feb;14(2):70-7
references: 16413190
references: J Bacteriol. 1983 May;154(2):998-1001
references: 6841322
references: J Bacteriol. 1985 Jan;161(1):25-31
references: 2857160
references: Eur J Biochem. 1988 Sep 1;176(1):1-19
references: 2901351
references: J Microbiol Methods. 2010 Sep;82(3):256-64
references: 20619305
references: Environ Microbiol. 2006 Feb;8(2):200-13
references: 16423009
references: Kidney Int. 1995 Oct;48(4):930-40
references: 8569102
references: Microbiol Mol Biol Rev. 2003 Dec;67(4):593-656
references: 14665678
references: J Immunol Methods. 1991 Mar 21;137(2):209-15
references: 1849541
references: Trends Microbiol. 1997 Jul;5(7):288-93
references: 9234512
references: Biochim Biophys Acta. 1978 Aug 17;511(3):305-19
references: 356882
references: Infect Immun. 2001 Mar;69(3):1671-8
references: 11179342
references: Biochim Biophys Acta. 1979 Mar 8;551(2):238-47
references: 369608
references: J Bacteriol. 2007 Sep;189(17):6222-35
references: 17601785
references: Science. 1992 Nov 27;258(5087):1479-81
references: 1279810
references: Infect Immun. 1998 Aug;66(8):3618-25
references: 9673241
references: Int J Syst Evol Microbiol. 2005 Sep;55(Pt 5):1863-1866
references: 16166679
references: Mol Microbiol. 1996 Jun;20(5):911-7
references: 8809744
references: FEMS Microbiol Rev. 2005 Nov;29(5):949-59
references: 16043254
references: Nucleic Acids Res. 2009 Jul;37(Web Server issue):W446-51
references: 19429691
references: J Bacteriol. 1986 Feb;165(2):379-85
references: 3944054
references: J Bacteriol. 1981 Apr;146(1):426-9
references: 7217005
references: Mol Microbiol. 2000 Nov;38(4):772-80
references: 11115112
references: Trends Biotechnol. 2006 Aug;24(8):364-71
references: 16820235
references: J Bacteriol. 1996 Jan;178(1):1-5
references: 8550401
references: J Bacteriol. 1984 Jan;157(1):13-20
references: 6690419
references: BMC Genomics. 2009 Dec 29;10:634
references: 20040079
references: Mol Microbiol. 2010 Nov;78(4):1004-17
references: 21062373
references: Biochim Biophys Acta. 1994 Jun 29;1197(2):167-96
references: 8031826
references: BMC Microbiol. 2005 Jan 26;5:5
references: 15673471
references: Mol Microbiol. 2004 Jan;51(2):319-34
references: 14756775
references: Methods Mol Biol. 2003;228:139-50
references: 12824550
references: Infect Immun. 1995 Jun;63(6):2387-9
references: 7768628
references: Infect Immun. 1982 Nov;38(2):745-54
references: 7141712
references: Nucleic Acids Res. 2005 Jan 1;33(Database issue):D164-8
references: 15608169
references: J Gen Microbiol. 1981 Apr;123(2):197-207
references: 7320696
references: J Bacteriol. 2010 Oct;192(19):5093-102
references: 20675479
references: Protein Sci. 2003 Aug;12(8):1652-62
references: 12876315
references: Proteomics. 2010 Dec;10(24):4363-76
references: 21136591
references: Nucleic Acids Res. 2010 Jan;38(3):868-77
references: 19923228
references: J Gen Microbiol. 1984 Jul;130(7):1765-80
references: 6470672
references: J Bacteriol. 2010 Jun;192(11):2852-60
references: 20348250
references: Mol Microbiol. 1994 Oct;14(2):283-90
references: 7830572
references: Mol Microbiol. 2008 Jan;67(2):403-19
references: 18086188
references: Proc Natl Acad Sci U S A. 1978 Aug;75(8):3751-5
references: 358202
references: Biochim Biophys Acta. 1986 Aug 21;860(2):268-76
references: 2427116