Antigenic Organization of the N-Terminal Part of the Polymorphic Outer Membrane Proteins 90, 91A, and 91B of Chlamydophila abortus

Abstract

A series of overlapping recombinant antigens, 61 to 74 residues in length, representing polymorphic outer membrane protein 90 (POMP90) of Chlamydophila abortus and two recombinant peptides spanning gene fragment p91Bf99 of POMP91B were assessed by immunoblotting to determine the antigen-binding sites of 20 monoclonal antibodies to POMP90, -91A, and -91B. The epitopes were further restricted by scanning 52 overlapping synthetic 12-mer peptides representing the N-terminal part of POMP90, and the 12-mer epitopes were then analyzed by using hexapeptides to the resolution of a single amino acid. Ten epitopes were defined: 1, TS EEFQVKETSSGT; 2, SGAIYTCEGNVCISYAGKDSPL; 3, SLVFHKNCSTAE; 4, AIYADKLTIVSGGPTLFS; 5, SPKGGAISIKDS; 6, ITFDGNKIIKTS; 7, LRAKDGFGIFFY; 7a, DGFGIF; 7b, GIFFYD; 8, IFFYDPITGGGS; 8a, FFYDPIT; 9, GKIVFSGE; and 10, DLGTTL. The 20-mer peptide LRAKDGFGIFFYDPITGGGS was a major epitope that was recognized by seven antibodies. Epitopes 7 to 10 were conserved in reference strains of the former species C. psittaci, whereas the strong antigenic peptides FYDPIT and IVFSGE were conserved among members of the genus Chlamydophila. Epitopes 3 to 8 were located within the best-scoring beta-helical wrap (residues 148 to 293) predicted for POMP91B by the program BETAWRAP. Other studies have suggested an association of the POMPs with type V secretory autotransporter proteins. The results presented in this study provide some evidence for a passenger domain that is folded as a beta-helix pyramid with compact antigenic organization.

From the inside out – processing of the Chlamydial autotransporter PmpD and its role in bacterial adhesion and activation of human host cells

“…For other Pmps, positive reacting bands at different sizes could be observed depending on the probe being denatured by boiling or not, which is in agreement with the known temperature‐dependent running behaviour of proteins containing pore‐like beta‐barrel structures (McCafferty et al ., 1995; Christiansen et al ., 1999; Knudsen et al ., 1999). In C. psittaci, only the N‐terminus of Pmps was found to be surface exposed forming a beta helix immunogenic in ovine infection, consistent with the model of a C‐terminal translocator unit incorporated in the OM (Everett and Hatch, 1995; Longbottom et al ., 1998; Vretou et al ., 2003).…”

“…In detail, after Sec‐dependent delivery into the periplasm, conserved C‐terminal transporter domain spontaneously forms a pore‐like beta‐barrel in the OM through witch the N‐terminal passenger domain leaves the bacterium (Pohlner et al ., 1987; Henderson, et al ., 1998). In case of C. trachomatis and C. psittaci , several Pmps [also called (P)Omps] were shown to be expressed late during the infection cycle and were present in OM‐complexes or on the bacterial surface, eliciting strong immune response in the course of natural infection (Knudsen et al ., 1999; Tanzer et al ., 2001; Tanzer and Hatch, 2001; Vretou et al ., 2003).…”

The Chlamydophila abortus genome sequence reveals an array of variable proteins that contribute to interspecies variation

“…2, pmp clusters 2 and 3). The products of these genes are part of a larger family of proteins known as the polymorphic membrane proteins (Pmp) that are represented in all of the sequenced Chlamydiaceae genomes (Vretou et al 2003): 9, 21, and 17 pmp genes have been reported within the genome sequences of C. trachomatis/C. muridarum, Cp.…”

“…Their high immunogenicity is also likely to be significant in the protective immunity conferred by chlamydial outer membrane preparations (Tan et al 1990;Cevenini et al 1991;Longbottom et al 1998b;Vretou et al 2003;Wehrl et al 2004). In total, Cp.…”

Members of the Pmp protein family of Chlamydia pneumoniae mediate adhesion to human cells via short repetitive peptide motifs

“…Pmp21 in Fig. 1B ) ( Vandahl et al ., 2001 ; 2002 ; Vretou et al ., 2003 ; Wehrl et al ., 2004 ; Kiselev et al ., 2009 ; Swanson et al ., 2009 ). However, there is no evidence for secretion of Pmps by the AT pathway.…”