Structural and polypeptide differences between envelopes of infective and reproductive life cycle forms of Chlamydia spp

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Abstract
Significant differences in cysteine-containing proteins and detergent-related solubility properties were observed between outer membrane protein complexes of reproductive (reticulate body) and infective (elementary body) forms of C. psittaci (6BC). Elementary bodies harvested at 48 h postinfection [from mouse fibroblast 929 L cells] possessed a 40-kilodalton major outer membrane protein and 3 extraordinarily cysteine-rich outer membrane proteins of 62, 59 and 12 kilodaltons, all of which were not solubilized by sodium dodecyl sulfate in the absence of thiol reagents. Intracellularly dividing reticulate bodies harvested at 21 h postinfection were severely deficient in the cysteine-rich proteins but possessed almost as much major outer membrane protein as did the elementary bodies. Most of the major outer membrane protein of reticulate bodies was solubilized by sodium dodecyl sulfate and was present in envelopes as monomers, although a proportion formed disulfide-cross-linked oligomers. By 21-24 h postinfection, reticulate bodies commenced synthesis of the cysteine-rich proteins which were found in outer membranes as disulfide-cross-linked complexes. The outer membranes of reticulate bodies of C. trachomatis (LGV434) [grown in human cervical carcinoma 229 HeLa cells] were also deficient in cysteine-rich proteins and more susceptible to dissociation in sodium dodecyl sulfate than were outer membranes of elementary bodies.