title: Ultrastructural analysis of the rugose cell envelope of a member of the Pasteurellaceae family.
abstract: Bacterial membranes serve as selective environmental barriers and contain determinants required for bacterial colonization and survival. Cell envelopes of Gram-negative bacteria consist of an outer and an inner membrane separated by a periplasmic space. Most Gram-negative bacteria display a smooth outer surface (e.g., Enterobacteriaceae), whereas members of the Pasteurellaceae and Moraxellaceae families show convoluted surfaces. Aggregatibacter actinomycetemcomitans, an oral pathogen representative of the Pasteurellaceae family, displays a convoluted membrane morphology. This phenotype is associated with the presence of morphogenesis protein C (MorC). Inactivation of the morC gene results in a smooth membrane appearance when visualized by two-dimensional (2D) electron microscopy. In this study, 3D electron microscopy and atomic force microscopy of whole-mount bacterial preparations as well as 3D electron microscopy of ultrathin sections of high-pressure frozen and freeze-substituted specimens were used to characterize the membranes of both wild-type and morC mutant strains of A. actinomycetemcomitans. Our results show that the mutant strain contains fewer convolutions than the wild-type bacterium, which exhibits a higher curvature of the outer membrane and a periplasmic space with 2-fold larger volume/area ratio than the mutant bacterium. The inner membrane of both strains has a smooth appearance and shows connections with the outer membrane, as revealed by visualization and segmentation of 3D tomograms. The present studies and the availability of genetically modified organisms with altered outer membrane morphology make A. actinomycetemcomitans a model organism for examining membrane remodeling and its implications in antibiotic resistance and virulence in the Pasteurellaceae and Moraxellaceae bacterial families.
authors: Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, USA.
authors: Fereshteh
authors: F
authors: Azari
authors: Lori
authors: L
authors: Nyland
authors: Chunxiao
authors: C
authors: Yu
authors: Michael
authors: M
authors: Radermacher
authors: Keith P
authors: KP
authors: Mintz
authors: Teresa
authors: T
authors: Ruiz
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission / Q000379:methods; D044007:Moraxellaceae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity / Q000648:ultrastructure*; D009154:Mutation; D015661:Pasteurellaceae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity / Q000648:ultrastructure*; D013499:Surface Properties; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins
references: Mol Microbiol. 1990 May;4(5):697-705
references: 2201866
references: Annu Rev Biochem. 2011;80:161-87
references: 21275640
references: Microbiology (Reading). 2004 Aug;150(Pt 8):2677-2688
references: 15289564
references: Microbiol Mol Biol Rev. 2010 Mar;74(1):81-94
references: 20197500
references: Biol Cell. 2006 Nov;98(11):667-78
references: 17042742
references: J Bacteriol. 2009 Oct;191(20):6253-61
references: 19717611
references: J Bacteriol. 1999 Aug;181(16):4725-33
references: 10438737
references: J Struct Biol. 1996 Jan-Feb;116(1):190-9
references: 8742743
references: J Bacteriol. 2008 May;190(9):3098-109
references: 18310342
references: Annu Rev Microbiol. 2007;61:191-214
references: 17506684
references: Mol Microbiol. 1996 Jul;21(1):21-31
references: 8843431
references: Langmuir. 2009 Apr 9;25(6):3728-33
references: 19227989
references: EMBO J. 2000 Nov 15;19(22):5989-99
references: 11080146
references: J Biol Chem. 1989 Sep 15;264(26):15451-6
references: 2670940
references: J Biol Chem. 2012 Jan 2;287(1):418-428
references: 22084237
references: Eur J Biochem. 1981 May 15;116(2):331-5
references: 7018907
references: J Bacteriol. 2003 Oct;185(20):6112-8
references: 14526023
references: Biochim Biophys Acta. 1968 Jan 3;150(1):159-61
references: 4868245
references: Mol Microbiol. 2007 Jan;63(2):545-58
references: 17163978
references: Microb Pathog. 2002 Jan;32(1):1-13
references: 11782116
references: Arch Microbiol. 1997 Jun;167(6):325-31
references: 9148773
references: Cold Spring Harb Perspect Biol. 2010 May;2(5):a000414
references: 20452953
references: Annu Rev Microbiol. 1969;23:159-98
references: 4186529
references: J Comput Chem. 2004 Oct;25(13):1605-12
references: 15264254
references: Electron Microsc Rev. 1992;5(1):77-103
references: 1730077
references: JAMA. 1979 Apr 27;241(17):1824-5
references: 430752
references: Nature. 2009 Jun 4;459(7247):651-2
references: 19494904
references: Swed Dent J Suppl. 1993;90:1-46
references: 8236029
references: Infect Immun. 2012 Jun;80(6):1948-57
references: 22409932
references: Microb Drug Resist. 1996 Spring;2(1):1-8
references: 9158716
references: Reprod Biol Endocrinol. 2004 Aug 24;2:61
references: 15327693
references: J Struct Biol. 1991 Dec;107(3):268-80
references: 1807357
references: S Afr Med J. 1983 Apr 9;63(15):580-1
references: 6845052
references: Mol Microbiol. 2006 Aug;61(4):839-46
references: 16879642
references: J Bacteriol. 1987 Jun;169(6):2659-66
references: 3294802
references: Infect Immun. 2006 Nov;74(11):6163-70
references: 17057091
references: Rev Sci Instrum. 2007 Jan;78(1):013705
references: 17503926
references: Adv Microb Physiol. 1979;20:163-250
references: 394591
references: J Struct Biol. 2012 Feb;177(2):439-46
references: 22155288
references: Clin Pediatr (Phila). 1984 Oct;23(10):578-80
references: 6467775
references: J Microsc. 1987 May;146(Pt 2):113-36
references: 3302267
references: J Bacteriol. 1999 Feb;181(4):1059-71
references: 9973330
references: Mol Microbiol. 2009 Jun;72(6):1395-407
references: 19432795
references: J Biol Chem. 2010 Sep 3;285(36):27536-44
references: 20566635
references: J Struct Biol. 2010 Jun;170(3):427-38
references: 20338243
references: Infect Immun. 2005 Mar;73(3):1635-43
references: 15731063
references: Gene. 2009 Aug 15;443(1-2):42-7
references: 19450669
references: J Bacteriol. 2008 Sep;190(17):5972-80
references: 18621903
references: J Bacteriol. 1991 Mar;173(5):1623-33
references: 1999383
references: J Struct Biol. 1996 Jan-Feb;116(1):71-6
references: 8742726
references: Infect Immun. 1994 Sep;62(9):3672-8
references: 8063383
references: J Biol Chem. 1972 Jun 25;247(12):3962-72
references: 4555955
references: Nat Rev Microbiol. 2008 Feb;6(2):111-20
references: 18197168
references: Trends Biochem Sci. 1991 Sep;16(9):328-9
references: 1949152