S-Adenosylmethionine-responsive cystathionine beta-synthase modulates sulfur metabolism and redox balance in Mycobacterium tuberculosis.Bandyopadhyay, P., Pramanick, I., Biswas, R., Ps, S., Sreedharan, S., Singh, S., Rajmani, R.S., Laxman, S., Dutta, S., Singh, A.
(2022) Sci Adv 8: eabo0097-eabo0097
- PubMed: 35749503
- DOI: https://doi.org/10.1126/sciadv.abo0097
- Primary Citation of Related Structures:
7XNZ, 7XOH, 7XOY
- PubMed Abstract:
Methionine and cysteine metabolisms are important for the survival and pathogenesis of Mycobacterium tuberculosis ( Mtb ). The transsulfuration pathway converts methionine to cysteine and represents an important link between antioxidant and methylation metabolism in diverse organisms. Using a combination of biochemistry and cryo-electron microscopy, we characterized the first enzyme of the transsulfuration pathway, cystathionine β-synthase ( Mtb Cbs) in Mtb . We demonstrated that Mtb Cbs is a heme-less, pyridoxal-5'-phosphate-containing enzyme, allosterically activated by S -adenosylmethionine (SAM). The atomic model of Mtb Cbs in its native and SAM-bound conformations revealed a unique mode of SAM-dependent allosteric activation. Further, SAM stabilized Mtb Cbs by sterically occluding proteasomal degradation, which was crucial for supporting methionine and redox metabolism in Mtb . Genetic deficiency of Mtb Cbs reduced Mtb survival upon homocysteine overload in vitro, inside macrophages, and in mice coinfected with HIV. Thus, the Mtb Cbs-SAM axis constitutes an important mechanism of coordinating sulfur metabolism in Mtb .
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka 560012, India.