Flagella and Pili

Biofilms are sessile microbial communities, the formation of which is initiated by surface attachment of individual bacteria, followed by cell-cell interactions and development in a three-dimensional structure of the colonies (O Toole et al., 2000). Biofilm formation is a multi-step development process over a period of several hours (Costerton et al., 1995). The initial surface interaction is mediated by flagella and pili functioning, then the exopolysaccharides stabilize the biofilm and, finally, intercellular communication occurs through signaling molecules (Watnic and Kolter, 1999). 

A subunit vaccine consists of one or more immunogenic epitopes, proteins, or other components of a pathogenic organism. Immunogenic epitopes can be chemically synthesized and are known as peptide vaccines, e.g., peptide vaccine candidates for foot-and-mouth disease virus. The pathogen could be disrupted, and one or more immunogenic proteins such as bacterial cell wall proteins flagella or pili and viral envelope, capsid, or nucleoproteins can be purified. The isolation of such components in purified form is sometimes cumbersome and expensive. However, bacterial exotoxins can be easily purified, inactivated, and used as toxoid vaccines. 

Ng SY, Chaban B, Jarrell KF. Archaeal flagella, bacterial flagella and type IV pili a comparison of genes and postttanslational modifications. J Mol Microbiol Biotechnol. 2006 11 167-91. 

Surface Appendages Flagella and Fimbriae 143 Table 4.4 Properties of F and 1 Pili on coH ... 

Klausen, M., Heydorn, A., Ragas, R, et al. (2003) Biofilm fmnation by Pseudomonas aeruginosa wild type, flagella and type IV pili mutants. Mol Microbiol 48, 1511-1524. 

Three types of thread-like appendages may be found growing from bacterial cells flagella, pili (fimbriae) and F-pili (sex strands). 

In general, virus receptors carry out normal functions in the cell. For example, in bacteria some phage receptors are pili or flagella, others are cell-envelope components, and others are transport binding proteins. The receptor for influenza vims is a glycoprotein found on red blood cells and on cells of the mucous membrane of susceptible animals, whereas the receptor site of poliovirus is a lipoprotein. However, many animal and plant viruses do not have specific attachment sites at all and the vims enters passively as a result of phagocytosis or some other endocytotic process. 

In Gram-negative bacteria which are characterised by a rather complex cell envelope, the CM is also referred to as inner membrane to distinguish it from a second lipid bilayer, termed outer membrane (OM). The space between these two layers is called the periplasm (PP). In the periplasmic space, many proteins are found with a variety of functions. Some are involved in biosynthesis and/or export of cell wall components and surface structures (e.g. pili, flagellae,... 

In addition to flagella, extremely thin, long, straight filaments known as pili or fimbriae (Fig. 1-2) project from the surfaces of many bacteria.14 The "sex pili" (F pili and I pili) of E. coli have a specific role in sexual conjugation. The similar but more numerous common pili or fimbriae range in thickness from 3 to 25 nm and in length from 0.2 to 2 pm. Pili are involved in adhesion of bacteria to surrounding materials or to other bacteria and facilitate bacterial infections.17-19 A typical E. coli cell has 100-300 pili.5... 

Pratt, L. A., and R. Kolter. 1998. Genetic analysis of Escherichia coli biofilm formation Roles of flagella, motility, chemotaxis and type I pili. Molecular Microbiology 30 285-293. 

Bacterial flagella, flagellar basal body, pili, and fimbriae... 

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