IDENTIFICATION, CHARACTERIZATION, AND DEVELOPMENTAL REGULATION OF CHLAMYDIA-TRACHOMATIS 3-DEOXY-D-MANNO-OCTULOSONATE (KDO)-8-PHOSPHATE SYNTHETASE AND CMP-KDO SYNTHETASE

The kdsA and kdsB genes from Chlamydia trachomatis encoding 3-deoxy-D- manno-octulosonate (KDO)-8-phosphate synthetase and CMP-KDO synthetase were identified by functional complementation of temperature-sensitiv e Salmonella typhimurium mutants, homology to known KDO-8-phosphate sy nthetase and CMP-KDO synthetase proteins, and in vitro enzyme activity , The kdsA gene was transcribed as part of a polycistronic mRNA with t wo downstream open reading frames (ORFs). One of these ORFs appeared t o encode a membrane-anchored protein, while the second encoded a prote in showing homology to the ATP-binding component of periplasmic bindin g protein-dependent ABC transporters, Transcription of kdsA and kdsB i n C. trachomatis was evident within 4 h of initiation of the C. tracho matis infection process and continued throughout the chlamydial life c ycle.