From Proteopedia

Introduction

Pertactin is a virulence toxin of Bordetella parapertussis and close relatives, such as Bordetella pertussis. It is an outer surface membrane protein involved in the binding of B. parapertussis to host cells, which aids the bacteria in infection of host cells with whooping cough.

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Structure and Protein Adhesion Properties

Function

Disease

Relevance

Pertactin vs Pertussis Toxin: Virulence Factors

Pertactin and Pertussis toxin are both virulence factors that contribute to respiratory tract infection and whooping cough. Both are responsible for binding the foreign bacterial cell to the host organism’s cells. Despite similar functions Pertactin and Pertussis toxin have very different structures. Pertussis toxin is a virulence factor only produced by Bordetella pertussis. It is known to cause systemic symptoms of pertussis disease, such as leukocytosis and histamine sensitivity. It has also, recently, been discovered to promote respiratory infection by inhibiting and modulating host cell immune responses. Pertussis toxin acts as a soluble factor, attacking resident cells of the trachea and lungs such as macrophages (). Pertussis toxin’s wide variety of functions is due to its ability to recognize numerous carbohydrate receptors on eukaryotic cells. Pertussis toxin consists of five different subunits, which most likely is responsible for its ability to recognize multiple receptors (). BLAST results revealed that a single domain is contained within subunits 1, 4 and 5: Pertussis_S1 superfamily, Pertussis_S4 superfamily and Pertussis_S5 superfamily. Subunits 2 and 3 contain an ATP superfamily and Pertussis_S2S3 Superfamily, which represent the N-terminal domain of aerolysin and pertussis toxin and the C-terminal domain, respectively. Pertactin is also a virulence factor known to contribute to whooping cough. Pertactin is found in Bordetella pampertussis, and a 91.3% homologous protein is found in Bordetella pertussis. An amino acid alignment between the two strains reveals that the proteins differ in the number of repeated sequences. B. pampertussis has a series of approximately twenty more amino acids beginning at the 581st position. Pertactin is involved in binding the bacterial cell to respiratory host cells (). BLAST results revealed that two domains, autotransporter and PL1_Passenger_AT, are conserved. The autotransporter domain is located at the C-terminus of Pertactin and functions to transport the passenger domain, located at the N-terminus of Pertactin, in to the host cell, where the two domains are typically cleaved. This process is responsible for the bacterial cell binding to the host cell. As a whole, Pertactin and Pertussis toxin are structurally very different. As mentioned previously, Pertactin’s structure consists of a 16-stranded parallel beta-helix with a v-shaped cross section, while Pertussis toxin consists of five subunits (). However, amino acid alignments between Pertactin and each of the five subunits of Pertussis toxin reveals that various sections of Pertactin are the same or highly similar to individual subunits of Pertussis toxin. BLAST results also revealed that subunits 4 and 5’s structures consist of an OB fold and a closed or partly open beta barrel. This may be how Pertactin and Pertussis toxin have similar functions.

=Pertactin Function vs Similarly Structured Proteins' Functions

Structural highlights

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References