Pilus

F-pili or sex strands are partofa primitive genetic exchange system in some bacterial species. Part of the genetic material may be passed from one cell to another through the hollow pilus, thus giving rise to a simple form of sexual reproduction. 

Enteropathogenic E. coli pilus subunit A (BfpA) Tobacco leaf Immunogenic when delivered orally in mice. Anti-BfpA in fecal matter. - 88... 

Nunn, D. (1999). Bacterial type II protein export and pilus biogenesis more than just homologies Trends Cell Biol. 9, 402-408. 

Knutton, S., Shaw, R. K., Anantha, R. P., Donnenberg, M. S., and Zorgani, A. A. (1999). The type rV bundle-forming pilus of enteropathogenic Escherichia coli undergoes dramatic alterations in structure associated with bacterial adherence, aggregation and dispersal. 

Lindberg, F., Lund, B., Johansson, L., and Normark, S. (1987). Localization of the receptor-binding protein adhesin at the tip of the bacterial pilus. Nature 328,84-87. 

Rendon, M. A., Saldana, Z., Erdem, A. L., Monteiro-Neto, V., Vazquez, A., Kaper, J. B., Puente, J. L., and Giron, J. A. (2007). Commensal and pathogenic Escherichia coli use a common pilus adherence factor for epithelial cell colonization. Proc. Natl. Acad. Sci. USA 104,10637-10642. 

Srimanote, P., Paton, A. W., and Paton, J. C. (2002). Characterization of a novel type IV pilus locus encoded on the large plasmid of locus of enterocyte effacement-negative Shiga-toxigenic Escherichia coli strains that are virulent for humans. Infect. Immun. 70,3094-3100. 

VirB proteins in the secretion system most form the membrane channel or serve as ATPases to provide energy for channel assembly or for export processes. Several of these VirB proteins form the T-pilus. The function of the T-pilus remains unclear it may be required as the channel for T-DNA and Vir protein transfer, or it may act as a hook to grab hold of the recipient host cell and bring plant and bacterium close together for efficient gene transfer (Gelvin, 2003, LaCroix et ah, 2006a). 

Quasi-equivalence in virus coats. A large number of icosahedral viruses have coats consisting of 180 identical subunits. For example, the small RNA-containing bacteriophage MS 2 consists of an eicosahedral shell of 180 copies of a 129-residue protein that encloses one molecule of a 3569-residue RNA.89 Tire virus also contains a single molecule of a 44-kDa protein, the A protein, which binds the virus to a bacterial pilus to initiate infection. Related bacteriophages GA, fr, f2, and QP90"1 have a similar... 

Bacterial pili appear to be extruded in a similar manner. They arise rapidly and may possibly be retracted again into the bacterial membrane. The P pilus in Fig. 7-9A is made up of subunits Pap A, G, F,... 

E, and K which must be assembled in the correct sequence. A chaperonin PapD is also required as is an "usher protein," PapC,50 and also the disulfide exchange protein DsbA (Chapter 10). DsbA helps PapD to form the correct disulfide bridges as it folds and PapD binds and protects the various pilus subunits as they accumulate in the periplasmic space of the host. The usher protein displaces the chaperonin PapD and "escorts" the subunits into the membrane where the extrusion occurs.50 55... 

When an Hfr strain conjugates with an F (female), replication of the entire male chromosome commences at some point near the end of the integrated F agent, and genes of the bacterial chromosome followed by those of the F factor are transferred into the female. Only a single strand of DNA (customarily referred to as the plus strand) is transferred from the donor cell and into the recipient cell (Fig. 26-3). There the complementary minus strand is synthesized to form a complete double-stranded DNA molecule bearing the genes from the Hfr cell. Only rarely does a copy of the entire chromosome of the donor cell enter the female cell. More often the DNA strand, or perhaps the pilus itself, breaks and only part of the chromosome is transferred. 

Microbial pathogens utilize different types of lectins for targeting the glycans on the surface of host cells. Many bacteria are covered with pili or fimbriae that contain a very special class of lectins known as adhesins because they play a role in attachment to epithelial cells. These lectins are monomeric and comprise only one binding site. Because the adhesins are repeated on the pilus, a larger number of adhesins on the bacterial surface create multivalent interaction with the host glycans. 

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