Lipid biosynthesis in the pathogen Mycobacterium tuberculosis depends on biotin for posttranslational modification of key enzymes. However, the mycobacterial biotin synthetic pathway is not fully understood. Here, we show that rv1590, a gene of previously unknown function, is required by M. tuberculosis to synthesize biotin. Chemical–generic interaction experiments mapped the function of rv1590 to the conversion of dethiobiotin to biotin, which is catalyzed by biotin synthases (BioB). Biochemical studies confirmed that in contrast to BioB of Escherichia coli, BioB of M. tuberculosis requires Rv1590 (which we named “biotin synthase auxiliary protein” or BsaP), for activity. We found homologs of bsaP associated with bioB in many actinobacterial genomes, and confirmed that BioB of Mycobacterium smegmatis also requires BsaP. Structural comparisons of BsaP-associated biotin synthases with BsaP-independent biotin synthases suggest that the need for BsaP is determined by the [2Fe–2S] cluster that inserts sulfur into dethiobiotin. Our findings open new opportunities to seek BioB inhibitors to treat infections with M. tuberculosis and other pathogens.

病原体结核分枝杆菌中的脂质生物合成依赖于生物素对关键酶的翻译后修饰。然而，分枝杆菌生物素合成途径尚未完全了解。在这里，我们证明了rv1590 （一种以前未知功能的基因）是结核分枝杆菌合成生物素所必需的。化学-通用相互作用实验将rv1590的功能映射到脱硫生物素向生物素的转化，该转化由生物素合酶 (BioB) 催化。生化研究证实，与大肠杆菌的 BioB 不同，结核分枝杆菌的 BioB 需要 Rv1590（我们将其命名为“生物素合酶辅助蛋白”或 BsaP）才能发挥活性。我们在许多放线菌基因组中发现了与bioB相关的bsaP同源物，并证实耻垢分枝杆菌的BioB也需要BsaP。 BsaP 相关生物素合酶与 BsaP 独立生物素合酶的结构比较表明，对 BsaP 的需求是由将硫插入脱硫生物素的 [2Fe-2S] 簇决定的。我们的研究结果为寻找 BioB 抑制剂来治疗结核分枝杆菌和其他病原体感染提供了新的机会。