The WhiA and WhiB2 transcription factors mediate the Mycobacterium tuberculosis cell cycle by regulating DNA replication and cell division.

Tuberculosis is caused by Mycobacterium tuberculosis (Mtb), a pathogen with a remarkable ability to survive within its human host by balancing replication and persistence throughout the course of infection. The success of Mtb depends on its ability to adapt to diverse and hostile environments imposed by the host. This adaptation is primarily mediated through transcriptional regulation of gene expression. While Mtb encodes several transcription factors essential for growth, it remains unclear which transcription factors directly regulate the bacterial cell cycle. In this work, we characterized two essential transcription factors, WhiA and WhiB2, and defined their role in regulating Mtb replication. Using CRISPR interference, we demonstrated that whiA and whiB2 are essential for bacterial cell division. Results from functional genomic studies revealed that WhiA and WhiB2 regulate key genes involved in DNA replication and repair, ribosome function, cell wall synthesis, and septation. Subsequent in vitro studies demonstrated that WhiA and WhiB2 are dually required for activation of selected target genes, suggesting that they function cooperatively as regulators of the Mtb cell cycle.