Processing of Chlamydia abortus polymorphic membrane protein 18D during the chlamydial developmental cycle

Area of Science:

• Microbiology
• Protein biochemistry
• Chlamydia research

Background:

• Chlamydia species utilize a unique family of autotransporter proteins called Polymorphic Membrane Proteins (Pmps).
• All Chlamydia species encode a single pmpD gene, and PmpD is known to be proteolytically cleaved on the cell surface in C. trachomatis and C. pneumoniae.

Purpose of the Study:

• To investigate the cleavage patterns of the PmpD protein in the animal pathogen Chlamydia abortus, referred to as Pmp18D.

Main Methods:

• Proteomic techniques utilizing region-specific antibodies against Pmp18D.
• Clustering analysis of PmpD proteins.

Main Results:

• Pmp18D undergoes cell surface cleavage, yielding a 100 kDa N-terminal product and a 60 kDa C-terminal protein.
• The N-terminal product is further processed into 84, 76, and 73 kDa fragments.
• Chlamydia abortus Pmp18D clusters with PmpD proteins from C. psittaci, C. felis, and C. caviae.

Conclusions:

• C. abortus Pmp18D exhibits cell surface proteolytic processing analogous to C. trachomatis and C. pneumoniae PmpD.
• Cleavage patterns of PmpD are species-specific, with limited sequence conservation across the Chlamydia genus.
• The functional significance of PmpD in Chlamydia remains undetermined due to the absence of conserved domains.