Tryptophan recycling is responsible for the interferon-γ resistance of Chlamydia psittaci GPIC in indoleamine dioxygenase-expressing host cells

摘要: Summary Comparative genomics indicates that vast differences in Chlamydia sp. host range and disease characteristics can be traced back to subtle variations gene content within a region of the chromosome termed plasticity zone. Genes required for tryptophan biosynthesis are located zone; however, complement genes encoded varies depending on chlamydial species examined. Of sequenced chlamydia genomes, psittaci GPIC contains most complete operon, encoding trpRDCFBA. Immediately downstream trp operon kynureninase ribose phosphate pyrophosphokinase. Here, we show that, GPIC, these transcribed as single transcript, expression which is regulated by tryptophan. Complementation analyses, using various mutant Escherichia coli isolates, indicate biosynthesis, pyrophosphokinase products functional. Furthermore, growth C. HeLa cells, cultured tryptophan-free medium, could rescued addition anthranilate, kynurenine or indole. In total, our results this enables recycle thus accounts interferon-γ resistant phenotype displayed indoleamine-2,3-dioxygenase-expressing cells.