Fig. 1

Contrasting patterns of stress response in enteric bacteria and M. tuberculosis

The idiosyncrasies of stress response (circles) in enteric bacteria (A) and M. tuberculosis (B) can be summarized as follows: (i) No significant overlap between \({{\rm{O}}_2}^{-.}\) and NO^· regulon in M. tuberculosis. (ii) The majority of \({{\rm{O}}_2}^{-.}\) induced polypeptides in M. tuberculosis are the previously characterized heat shock proteins (Hsp), with the exception of the newly identified \({{\rm{O}}_2}^{-.}\) inducible polypeptide Mnd86. (iii) NO^· induces a number of polypeptides (designated as Nox followed by apparent M_r) that appear not to be inducible by other stress factors tested. (iv) M. tuberculosis has multiple lesions in oxyR (24) as illustrated in Panel C (comparison with a functional oxyR gene from M. leprae; deletions are marked as filled rectangles). Consistent with these findings, there is no differential induction of gene expression in M. tuberculosis exposed to H₂O₂ except in the case of katG, which appears to be affected in combination with other cultural conditions (e.g., slightly elevated temperature) (24). HS, heat shock. Genes and protein names are explained in the text.