Bacterial Cell Wall

Kevin D Young, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA

Published online: April 2010

DOI: 10.1002/9780470015902.a0000297.pub2

Most bacteria are encased in walls that protect the cells against lysis by osmotic forces from within and from chemical or biological assaults from outside. These walls are assembled in layers consisting of four principal components: inner membrane, peptidoglycan, outer membrane and S-layer. The first two are the basic constituents of bacterial walls, the outer membrane is a hallmark of one branch of bacteria and S-layers are optional in many different microorganisms. The two fundamental types of wall are Gram-type positive, which have no outer membrane, and Gram-type negative, which have an outer membrane. Bacteria also produce various secondary polymers, such as teichoic or mycolic acids, that associate with peptidoglycan and alter its chemical characteristics. Finally, and in addition to its protective role, the wall imparts to bacterial cells their specific shapes and is organised to facilitate the transport of vital chemicals into and out of the cell.

Key Concepts:

  • The cell wall protects bacteria from lysis, chemical assault and attack by the immune system.
  • The bacterial cell wall consists of an inner (plasma) membrane, a rigid peptidoglycan exoskeleton and, in some cases, an outer membrane and/or an S-layer.
  • Peptidoglycan is composed of a long chain of repeating disaccharides linked to one another by short peptide side chains, which creates a single macromolecule surrounding the bacterial cell.
  • The biological properties of many bacterial cell walls are strengthened or enhanced by the addition of secondary cell wall glycopolymers.
  • The bacterial world is divided into two main groups: those that have a single membrane (the plasma or inner membrane) and those that have two membranes (inner and outer membranes).
  • S-layers are paracrystalline arrays of a single protein that completely cover the exterior of many bacteria.
  • Bacterial shape is determined by cytoskeleton proteins that direct the synthesis of the overall structure of peptidoglycan.

Keywords: Gram-positive walls; Gram-negative walls; peptidoglycan; teichoic acid; periplasm; periplasmic space; S-layers; cell shape; microscopy

Figure 1. Basic types of bacterial cell walls. The individual components of the walls, which are layered on top of one another, are depicted as coloured rectangles: inner membrane (light blue), peptidoglycan (rust red), outer membrane (dark blue) and S-layer (orange). Different types of walls are created by assembling various combinations of the components ((a)–(f)). Each type is described briefly underneath its column, and one or two examples of organisms that have that wall type are listed in parentheses.
Figure 2. Electron micrographs of thin sections of bacterial cell walls. (a) The fibrous nature of the Gram-positive cell wall of Bacillus subtilis. The fuzziness of the wall exterior is due to cell wall turnover. The wall is very thick but hydrolytic enzymes cut the peptidoglycan at intervals, beginning from the outside of the cell and working inwards, thus producing the hairy exterior seen here. Newly synthesised peptidoglycan is highly compacted and stains as a very dark band immediately above the (plasma) membrane. (b) The arrangement of a growing septum (arrows) in Bacillus licheniformis as the cell undergoes binary fission. During cell division of this Gram-positive rod, the septum will grow inwards until the cell is bisected to divide the cell into two daughter cells. (c) Cross-section of frozen-hydrated B. subtilis 168. High magnification image of the envelope showing the plasma membrane (PM) enclosed by a low-density inner wall zone (IWZ) which is bound by a high-density outer wall zone (OWZ). Bar represents 50 nm. Note that this technique preserves and allows visualisation of a more complete structure than does the classical procedure in (a). Reprinted from Matias VRF and Beveridge TJ (2005). Molecular Microbiology 56: 240–251, with permission from Wiley-Blackwell. (d) A frozen-hydrated section of the Gram-negative cell wall from E. coli K12. The outer membrane (OM) and plasma (inner) membrane (PM) surround the cell. The space between the two is the periplasmic space. Within the periplasm is a thin line of peptidoglycan (PG) that is much less thick than the peptidoglycan of Gram-positive cell walls. The bar equals 200 nm. Reprinted from Matias et al. (2003), with permission from the American Society for Microbiology.
Figure 3. Schematic diagram showing the relationship between the glycan chains and peptide crosslinks in the most basic form of peptidoglycan.
Figure 4. Schematic structures of selected cell wall glycopolymers (CWGs). Selected CWGs are divided into those attached to peptidoglycan and those anchored to the IM, with examples of individual organisms that contain each compound given in parentheses. The chemical constituents are denoted as follows: trioses (triangles), peptoses (pentagons), hexoses (hexagons), peptidoglycan sugar residues (teal), other sugars (yellow), sugar-derived alcohols (orange), sugar-derived acids (purple) and fatty acids (zigzag lines). Many structural details, such as sugar-bonding patterns, are not included. It is thought most likely that N-acetylglucosamine (GlcNAc) occurs in the first position of B. subtilis teichuronic acid and in the first position of the B. anthracis P-CWG. Uncertain second positions are indicated by question marks. The exact position of pyruvylation in B. anthracis P-CWG is unknown. Mycobacterial CWGs are more extensively branched than indicated in this schematic. Non-glycosyl residues are designated as follows: A, d-alanine; C, choline; M, mycolic acid; P, phosphate; S, succinate; Y, pyruvate. Glycosyl residues: AAT-Gal, 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose; Ara, arabinose; Gal, galactose; GalNAc, N-acetylgalactosamine; Glc, glucose; GlcA, glucuronic acid; Gro, glycerol; Ins, inositol; Man, mannose; ManNAc, N-acetylmannosamine; Rha, rhamnose; Rto, ribitol. Reproduced from Weidenmaier and Peschel (2008) with permission from Nature Publishing Group.
Figure 5. Electron micrograph of the negatively stained S-layer from Synechococcus GL24. The subunits are hexagonally arranged and form a p6 lattice.
close
 References
    Andre G, Leenhouts K, Hols P and Dufrene YF (2008) Detection and localization of single LysM-peptidoglycan interactions. Journal of Bacteriology 190: 7079–7086.
    Barak I, Muchova K, Wilkinson AJ, O'Toole PJ and Pavlendova N (2008) Lipid spirals in Bacillus subtilis and their role in cell division. Molecular Microbiology 68: 1315–1327.
    Bardy SL and Maddock JR (2007) Polar explorations: recent insights into the polarity of bacterial proteins. Current Opinion in Microbiology 10: 617–623.
    Beveridge TJ (1990) Mechanism of Gram variability in select bacteria. Journal of Bacteriology 172: 1609–1620.
    Beveridge T (2006) Visualizing bacterial cell walls and biofilms. Microbe 1: 279–284.
    Beveridge TJ and Davies JA (1983) Cellular responses of Bacillus subtilis and E. coli to the Gram stain. Journal of Bacteriology 156: 846–858.
    Beveridge TJ and Graham LL (1991) Surface layers of bacteria. Microbiological Reviews 55: 684–705.
    book Beveridge TJ, Popkin TJ and Cole RM (1994) "Electron microscopy". In: Gerhardt P, Murray RGE, Wood WA and Krieg NR (eds) Methods for General and Molecular Bacteriology, pp. 42–71. Washington DC: American Society for Microbiology.
    Brennan PJ (2003) Structure, function, and biogenesis of the cell wall of Mycobacterium tuberculosis. Tuberculosis (Edinburgh) 83: 91–97.
    Carballido-López R and Formstone A (2007) Shape determination in Bacillus subtilis. Current Opinion in Microbiology 10: 611–616.
    Daniel RA and Errington J (2003) Control of cell morphogenesis in bacteria. Two distinct ways to make a rod-shaped cell. Cell 113: 767–776.
    D'Elia MA, Millar KE, Beveridge TJ and Brown ED (2006a) Wall teichoic acid polymers are dispensable for cell viability in Bacillus subtilis. Journal of Bacteriology 188: 8313–8316.
    D'Elia MA, Millar KE, Bhavsar AP et al. (2009) Probing teichoic acid genetics with bioactive molecules reveals new interactions among diverse processes in bacterial cell wall biogenesis. Chemistry and Biology 16: 548–556.
    D'Elia MA, Pereira MP, Chung YS et al. (2006b) Lesions in teichoic acid biosynthesis in Staphylococcus aureus lead to a lethal gain of function in the otherwise dispensable pathway. Journal of Bacteriology 188: 4183–4189.
    Ebersbach G and Jacobs-Wagner C (2007) Exploration into the spatial and temporal mechanisms of bacterial polarity. Trends in Microbiology 15: 101–108.
    Engelhardt H (2007) Are S-layers exoskeletons? The basic function of protein surface layers revisited. Journal of Structural Biology 160: 115–124.
    Gan L, Chen S and Jensen GJ (2008) Molecular organization of Gram-negative peptidoglycan. Proceedings of the National Academy of Sciences of the USA 105: 18953–18957.
    Ghosh AS and Young KD (2005) Helical disposition of proteins and lipopolysaccharide in the outer membrane of E. coli. Journal of Bacteriology 187: 1913–1922.
    Graham LL, Beveridge TJ and Nanninga N (1991) Periplasmic space and the concept of the periplasm. Trends in Biochemical Sciences 16: 328–329.
    Hayhurst EJ, Kailas L, Hobbs JK and Foster SJ (2008) Cell wall peptidoglycan architecture in Bacillus subtilis. Proceedings of the National Academy of Sciences of the USA 105: 14603–14608.
    Hobot JA, Carlemalm E, Villiger W and Kellenberger E (1984) Periplasmic gel: new concept resulting from the reinvestigation of bacterial cell envelope ultrastructure by new methods. Journal of Bacteriology 160: 143–152.
    Hoffmann C, Leis A, Niederweis M, Plitzko JM and Engelhardt H (2008) Disclosure of the mycobacterial outer membrane: cryo-electron tomography and vitreous sections reveal the lipid bilayer structure. Proceedings of the National Academy of Sciences of the USA 105: 3963–3967.
    Kohler T, Weidenmaier C and Peschel A (2009) Wall teichoic acid protects Staphylococcus aureus against antimicrobial fatty acids from human skin. Journal of Bacteriology 191: 4482–4484.
    Lam JS, Graham LL, Lightfoot J, Dasgupta T and Beveridge TJ (1992) Ultrastructural examination of the lipopolysaccharides of Pseudomonas aeruginosa strains and their isogenic rough mutants by freeze-substitution. Journal of Bacteriology 174: 7159–7167.
    Letek M, Fiuza M, Ordonez E et al. (2008) Cell growth and cell division in the rod-shaped actinomycete Corynebacterium glutamicum. Antonie van Leeuwenhoek 94: 99–109.
    Lybarger SR and Maddock JR (2001) Polarity in action: asymmetric protein localization in bacteria. Journal of Bacteriology 183: 3261–3267.
    Matias VR, Al-Amoudi A, Dubochet J and Beveridge TJ (2003) Cryo-transmission electron microscopy of frozen-hydrated sections of E. coli and Pseudomonas aeruginosa. Journal of Bacteriology 185: 6112–6118.
    Matias VR and Beveridge TJ (2006) Native cell wall organization shown by cryo-electron microscopy confirms the existence of a periplasmic space in Staphylococcus aureus. Journal of Bacteriology 188: 1011–1021.
    Messner P and Sleytr UB (1992) Crystalline bacterial cell-surface layers. Advances in Microbial Physiology 33: 213–275.
    Messner P, Steiner K, Zarschler K and Schäffer C (2008) S-layer nanoglycobiology of bacteria. Carbohydrate Research 343: 1934–1951.
    Mühlradt PF, Menzel J, Golecki JR and Speth V (1974) Lateral mobility and surface density of lipopolysaccharide in the outer membrane of Salmonella typhimurium. European Journal of Biochemistry 43: 533–539.
    book Nikaido H (1996) "Outer membrane". In: Neidhardt FC, Curtiss R III, Ingraham JL, Lin CC, Low KB, Magasanik B, Reznikoff WS, Riley M, Schaechter M and Umbarger HE (eds) E. coli and Salmonella: Cellular and Molecular Biology, vol. 1, p. 1549. Washington DC: American Society for Microbiology.
    Nikaido H (2003) Molecular basis of bacterial outer membrane permeability revisited. Microbiology and Molecular Biology Reviews 67: 593–656.
    Osborn MJ and Rothfield L (2007) Cell shape determination in E. coli. Current Opinion in Microbiology 10: 606–610.
    de Pedro MA, Grunfelder CG and Schwarz H (2004) Restricted mobility of cell surface proteins in the polar regions of E. coli. Journal of Bacteriology 186: 2594–2602.
    de Pedro MA, Quintela JC, Höltje JV and Schwarz H (1997) Murein segregation in E. coli. Journal of Bacteriology 179: 2823–2834.
    de Pedro MA, Schwarz H and Koch AL (2003) Patchiness of murein insertion into the sidewall of E. coli. Microbiology 149: 1753–1761.
    Pichoff S and Lutkenhaus J (2007) Overview of cell shape: cytoskeletons shape bacterial cells. Current Opinion in Microbiology 10: 601–605.
    Pittenauer E, Quintela JC, Schmid ER et al. (1995) Characterization of Braun's lipoprotein and determination of its attachment sites to peptidoglycan by 252Cf-PD and MALDI time-of-flight mass spectrometry. Journal of the American Society for Mass Spectrometry 6: 892–905.
    Sára M and Sleytr UB (1996) Crystalline bacterial cell surface layers (S-layers): from cell structure to biomimetics. Progress in Biophysics and Molecular Biology 65: 83–111.
    Sára M and Sleytr UB (2000) S-layer proteins. Journal of Bacteriology 182: 859–868.
    Schleifer KH and Kandler O (1972) Peptidoglycan types of bacterial cell walls and their taxonomic implications. Bacteriological Reviews 36: 407–477.
    Sleytr UB and Beveridge TJ (1999) Bacterial S-layers. Trends in Microbiology 7: 253–260.
    Steen A, Buist G, Leenhouts KJ et al. (2003) Cell wall attachment of a widely distributed peptidoglycan binding domain is hindered by cell wall constituents. Journal of Biological Chemistry 278: 23874–23881.
    Takeuchi Y and Nikaido H (1981) Persistence of segregated phospholipid domains in phospholipid-lipopolysaccharide mixed bilayers: studies with spin-labeled phospholipids. Biochemistry 20: 523–529.
    Wang Y (2002) The function of OmpA in E. coli. Biochemical and Biophysical Research Communications 292: 396–401.
    Weidenmaier C and Peschel A (2008) Teichoic acids and related cell-wall glycopolymers in Gram-positive physiology and host interactions. Nature Reviews. Microbiology 6: 276–287.
    Yamamoto H, Miyake Y, Hisaoka M, Kurosawa S and Sekiguchi J (2008) The major and minor wall teichoic acids prevent the sidewall localization of vegetative DL-endopeptidase LytF in Bacillus subtilis. Molecular Microbiology 70: 297–310.
    Zapun A, Vernet T and Pinho MG (2008) The different shapes of cocci. FEMS Microbiology Reviews 32: 345–360.
    Zuber B, Chami M, Houssin C et al. (2008) Direct visualization of the outer membrane of Mycobacteria and Corynebacteria in their native state. Journal of Bacteriology 190: 5672–5680.
 Further Reading
    den Blaauwen T, de Pedro MA, Nguyen-Distèche M and Ayala JA (2008) Morphogenesis of rod-shaped sacculi. FEMS Microbiology Reviews 32: 321–344.
    Cabeen MT and Jacobs-Wagner C (2007) Skin and bones: the bacterial cytoskeleton, cell wall, and cell morphogenesis. Journal of Cell Biology 179: 381–387.
    Jensen GJ and Briegel A (2007) How electron cryotomography is opening a new window onto prokaryotic ultrastructure. Current Opinion in Structural Biology 17: 260–267.
    Milne JL and Subramaniam S (2009) Cryo-electron tomography of bacteria: progress, challenges and future prospects. Nature Reviews. Microbiology 7: 666–675.
    Schäffer C and Messner P (2005) The structure of secondary cell wall polymers: how Gram-positive bacteria stick their cell walls together. Microbiology 151: 643–651.
    book Sleytr UB, Messner P, Pum D and Sára M (eds) (1996) Cyrstalline Bacterial Cell Surface Proteins. Austin, TX: RG Landes Co., Academic Press.
    Vollmer W, Blanot D and de Pedro MA (2008) Peptidoglycan structure and architecture. FEMS Microbiology Reviews 32: 149–167.
    Vollmer W and Höltje JV (2004) The architecture of the murein (peptidoglycan) in gram-negative bacteria: vertical scaffold or horizontal layer(s)? Journal of Bacteriology 186: 5978–5987.
    Young KD (2006) The selective value of bacterial shape. Microbiology and Molecular Biology Reviews 70: 660–703.

Related Sub-Topics:

Composition and Structure of Microbial Cells | Bacteria
Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Bacterial Cell Wall
 
How to Cite close
Young, Kevin D(Apr 2010) Bacterial Cell Wall. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0000297.pub2]