Structural and DNA binding properties of mycobacterial integration host factor mIHF.

In bacteria, nucleoid associated proteins (NAPs) take part in active chromosome organization by supercoil management, three-dimensional DNA looping and direct transcriptional control. Mycobacterial integration host factor (mIHF, rv1388) is a NAP restricted to Actinobacteria and essential for survival of the human pathogen Mycobacterium tuberculosis. We show in vitro that DNA binding by mIHF strongly stabilizes the protein and increases its melting temperature.

EspL is essential for virulence and stabilizes EspE, EspF and EspH levels in Mycobacterium tuberculosis.

The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis, one of the most successful intracellular pathogens. Here, by combining genetic and high-throughput approaches, we show that EspL, a protein of 115 amino acids, is essential for mediating ESX-1-dependent virulence and for stabilization of EspE, EspF and EspH protein levels. Indeed, an espL knock-out mutant was unable to replicate intracellularly, secrete ESX-1 substrates or stimulate innate cytokine production.

Essential Nucleoid Associated Protein mIHF (Rv1388) Controls Virulence and Housekeeping Genes in Mycobacterium tuberculosis.

Tight control of gene expression is crucial for Mycobacterium tuberculosis to adapt to the changing environments encountered when infecting or exiting human cells. While three nucleoid associated proteins (NAPs) EspR, HupB and Lsr2 have been investigated, the role of a fourth, the mycobacterial integration host factor (mIHF), remains elusive. Here, we report a multidisciplinary functional analysis that exploits a conditional mIHF mutant.

Rv3852 (H-NS) of Mycobacterium tuberculosis Is Not Involved in Nucleoid Compaction and Virulence Regulation.

A handful of nucleoid-associated proteins (NAPs) regulate the vast majority of genes in a bacterial cell. H-NS, the istone-like ucleoid-tructuring protein, is one of these NAPs and protects from foreign gene expression. Though lacking any sequence similarity with H-NS, Rv3852 was annotated as the H-NS ortholog in , as it resembles human histone H1.