Pertactin


In molecular biology, pertactin (PRN) is a highly immunogenic virulence factor of Bordetella pertussis, the bacterium that causes pertussis. Specifically, it is an outer membrane protein that promotes adhesion to tracheal epithelial cells. PRN is purified from Bordetella pertussis and is used for the vaccine production as one of the important components of acellular pertussis vaccine.[2]

Pertactin
Bordetella pertussis Virulence Factor P.69 Pertactin. PDB entry 1dab[1]
Identifiers
SymbolPRN
PfamPF03212
InterProIPR004899
PROSITEPDOC00271
SCOPe1dab / SUPFAM

A large part of the N-terminus of the pertactin protein is composed of beta helix repeats.[3] This region of the pertactin protein is secreted through the C-terminal autotransporter. The N-terminal signal sequences promotes the secretion of PRN into the periplasm through the bacterial secretion system (Sec) and consequently, the translocation into the outer membrane where it is proteolytically cleaved.[4] The loops in the right handed β-helix of the N-terminus that protrudes out of cell surface (region R1) contains sequence repeats Gly-Gly-Xaa-Xaa-Pro and the RGD domain Arg-Gly-Asp.[4] This RGD domain allows PRN to function as an adhesin and invasin, binding to integrins on the outer membrane of the cell. Another loop of the extending β-helix is region 2 (R2) which contains Pro-Gln-Pro (PQP) repeats towards the C-terminus.[4] This protein’s contribution to immunity is still premature. Reports suggest that R1 and R2 are immunogenic regions, however, recent studies regarding genetic variation of those regions prove otherwise.

In B.bronchiseptica

Pertactin adheres to only ciliated epithelial cells of B. bronchiseptica in vivo. However, in vitro, PRN does not adhere to either. PRN does however help provide resistance towards a hyperinflammatory response of innate immunity for B. bronchiseptica. With respect to the adaptive immunity, studies show that PRN plays a role in combating neutrophil-mediated clearance of B. bronchiseptica.[4]

References

  1. Emsley, P.; Charles, I. G.; Fairweather, N. F.; Isaacs, N. W. (1996). "Structure of Bordetella pertussis virulence factor P.69 pertactin". Nature. 381 (6577): 90–92. doi:10.1038/381090a0. PMID 8609998.
  2. Poolman JT, Hallander HO (February 2007). "Acellular pertussis vaccines and the role of pertactin and fimbriae". Expert Rev Vaccines. 6 (1): 47–56. doi:10.1586/14760584.6.1.47. PMID 17280478.
  3. Emsley P, Charles IG, Fairweather NF, Isaacs NW (May 1996). "Structure of Bordetella pertussis virulence factor P.69 pertactin". Nature. 381 (6577): 90–2. doi:10.1038/381090a0. PMID 8609998.
  4. Inatsuka CS, Xu Q, Vujkovic-Cvijin I, Wong S, Stibitz S, Miller JF, Cotter PA (July 2010). "Pertactin is required for Bordetella species to resist neutrophil-mediated clearance". Infection and Immunity. 78 (7): 2901–9. doi:10.1128/IAI.00188-10. PMC 2897405. PMID 20421378.