Investigation of molecular factors involved in mycobacterial stress responses and non-replicating persistence

Mycobacterium tuberculosis is a remarkably successful human pathogen due to its ability to switch into dormancy or non-replicating persistence (NRP) phase driven by the host stress microenvironments. Identifying the panoply of genes or pathways involved in dormancy will progress our understanding on latent tuberculosis infection. Rv2660c and Rv2661c (conserved hypothetical proteins) and Rv1675c (transcriptional regulator) were implicated in mycobacterial stress response and transition to dormancy, hence their biological importance in M. tuberculosis biology was further explored. Rv2660c and rv2661c were highly upregulated in vitro starvation and in vivo infection model, however, recent high upregulation of a noncoding RNA, ncRv12659 in these models challenged the importance of these genes for NRP. A panel of single and double in-frame deletion mutants and over-expressing strains of rv2660c and rv2661c in M. tuberculosis were generated. A deletion of rv2660c and rv2661c also resulted in partial inactivation of ncRv12659 and rv2662 respectively. The deletion mutants exhibited normal growth in vitro and in mice. Furthermore, the strains showed unimpaired survival under nutrient starvation, hypoxia, oxidative ... (continues)