Equal opportunity nitrogen sourcing

Abstract

Pathogen Metabolism M ycobacterium tuberculosis (Mtb) has an unusual growth profile and metabolism, requiring around 20 hours to double in rich culture medium. A better understanding of Mtb metabolic requirements, particularly fundamental transformations such as nitrogen assimilation, may reveal weaknesses that can be exploited in drug design or other therapies. Agapova et al. cultured Mtb with each of the 20 proteinogenic amino acids, looking for differences in how nitrogen was incorporated into metabolites in the growing cells. Intracellular pools of amino acids varied in every case, suggesting a complex and flexible metabolism in which nitrogen is ideally obtained from amino acids rather than free ammonium. The enzyme alanine dehydrogenase exclusively liberated ammonium from alanine, suggesting a possible role for this enzyme and amino acid in nitrogen storage in Mtb. eLife 8 , e41129 (2019).