Table 1.
Lesions in numerous loci impact the thiamine biosynthetic pathway
| Lesions that allow thiamine-independent growth of a purF mutant on glucose minimal media | |||
|---|---|---|---|
| Locus | Function | Mechanism of integration | Refs |
| purE | Phosphoribosylaminoimidazole carboxylase catalytic subunit (EC 4.1.1.21) | Diverts all PurF-independent PRA formed to thiamine synthesis | [15] |
| prsA | Phosphoribosylpyrophosphate synthetase (EC 2.7.6.1), essential enzyme | Compromised PrsA activity results in accumulation of substrate R5P and allows non-enzymatic PRA synthesis | [19] |
| trpC | Phosphoribosyl-anthranilate isomerase (EC 5.3.1.24) and indole-3-glycerol-phosphate synthase (EC 4.1.1.48) | Compromised TrpC activity: substrate accumulates, breaks down to increased R5P and allows non-enzymatic PRA synthesis | [21] |
| yjgF | Unknown, member of the YjgF/YER057c/UK114 family of proteins that exist in all three domains of life | Unknown, TrpD is necessary and sufficient for synthesis of PRA. Direct formation hypothesized | [42] |
| pykAF | Pyruvate kinase isozymes I and II (EC 2.7.1.40) | Unknown, allows for thiamine synthesis in gluconate media in the presence of additional mutations | [60] |
| Lesions that prevent thiamine independent growth of a purF mutant on gluconate minimal media | |||
| gnd | 6-phosphogluconate dehydrogenase (EC 1.1.1.44) | Decreased cellular R5P levels on glucose or gluconate media | [16] |
| zwf | Glucose-6-phosphate 1-dehydrogenase (EC 1.1.1.49) | Decreased cellular R5P levels on glucose media | [15] |
| panE | 2-dehydropantoate 2-reductase (EC 1.1.1.169) | Decreased cellular CoA levels due to a defect in pantothenate biosynthesis | [61, 62] |
| nuo | NADH dehydrogenase complex I | Unknown | [63] |
| iscRSUA | Housekeeping [Fe-S] cluster assembly proteins | Disrupts Fe-S cluster metabolism | [64] |
| apbC | [Fe-S] cluster carrier protein | Disrupts Fe-S cluster metabolism | [65, 66] [27] |
| abpE | Unknown lipoprotein, shares homology with the C-terminus of RnfF, a putative membrane complex protein involved in electron transport to nitrogenase, from Rhodobacter capsulatus | Disrupts Fe-S cluster metabolism | [26, 67] [68] |
| rseC | SoxR reducing system protein | Disrupts Fe-S cluster metabolism | [30] [35] |
| gshA | Glutamate-cysteine ligase (EC 6.3.2.2) | Disrupts Fe-S cluster metabolism, unable to produce glutathione | [26] |