Developmental expression of non-coding RNAs in Chlamydia trachomatis during normal and persistent growth." Nucleic Acids Res

Chlamydia trachomatis is an obligate intracellular bacterium that exhibits a unique biphasic develop-mental cycle that can be disrupted by growth in the presence of IFN-c and b-lactams, giving rise to an abnormal growth state termed persistence. Here we have examined the expression of a family of non-coding RNAs (ncRNAs) that are differentially expressed during the developmental cycle and the induction of persistence and reactivation. ncRNAs were initially identified using an intergenic tiling microarray and were confirmed by northern blotting. ncRNAs were mapped, characterized and compared with the previously described chlamydial ncRNAs. The 50- and 30-ends of the ncRNAs were determined using an RNA circularization procedure. Promoter predictions indicated that all ncRNAs were expressed from p66 promoters and eight ncRNAs contained non-templated 30-poly-A or poly-AG additions. Expression of ncRNAs was studied by northern blotting during (i) the normal developmental cycle, (ii) IFN-c-induced persistence and (iii) carbenicillin-induced persistence. Differential temporal expression during the develop-mental cycle was seen for all ncRNAs and distinct differences in expression were seen during IFN-c and carbenicillin-induced persistence and reactiva-tion. A heterologous co-expression system was used to demonstrate that one of the identified ncRNAs regulated the expression of FtsI by inducing degradation of ftsI mRNA