FBXO39 and proctitis: We also clarified that the genes encoding CT142, CT143, and CT144 form an operon and their expression is likely driven by a σ66 promoter upstream from the start codon of ct142. In a previous RNA sequencing analysis of the transcriptome of C. trachomatis LGV serovar L2b strain UCH-1/proctitis there was no obvious definition of a transcription start site for ct142 (CTLon_0393), ct143 (CTLon_0394), or ct144 (CTLon_0395) [71].