THIAMINE 331 



Table 1. Response of Fungi to Thiamine and Its Moieties* 



Minimum 

 Requirement Examples 



Intact thiamine Ceratostomella fimbriala, Chalaropsis thielavioides (220), Cortinarius 



glaucopus (167); Phytophthora spp. (188, 204), Tilletia tritici 

 (46), Trichophyton discoides (222) 



Both moieties Boletus variegatus (167); Ceratostomella spp. (220), Marasmius 



perforans (145), Phycomyces spp. (130, 205, 210), Piricularia 

 oryzae (284), Polyporus versicolor (220), Tilletia horrida (245), 

 Ustilago spp. (15) 



Thiazole Collybia velutipes\ (1 56), Endomyces magnusii (165), Mucor raman- 



nianus (173, 174), Stereum frustulosum (182) 



Pyrimidine Allomyces kniepii (196), Blakeslea tiispora (130), Blastocladiella 



emersonii (7), Ceratostomella spp. (220), Cercosporella herpotri- 

 choides (45), Collybia tuber osa, Coprinus lagopus (130), Fomes 

 spp. (332), Hypholoma fascicular e (245), Marasmius fulvobul- 

 billosus (145), Nocardia spp. (157), Polyporus spp. (332), 

 Sclerotium spp. (205), Sphaerulina trifolii (210), Stereum murraii 

 (208), Trichophyton tonsurans (273) 



* A more inclusive list is given by Robbins and V. Kavanagh (213). 

 f Not definitely established. 



to live with either moiety alone does in fact make the other and syn- 

 thesize thiamine (14, 21, 133, 220, 239); neither pyrimidine nor thiazole 

 by itself has a vitamin function. 



A great deal of attention has been devoted to the specificity of the 

 structures of thiazole and pyrimidine for fungi. In general, the require- 

 ments are quite specific (213, 225, 239); most utilizable modifications, 

 e.g., the substitution of an acetyl for a hydroxyl group or of an ethyl 

 for a methyl group, are either minor or are very likely transformed 

 biologically into the natural product. Allithiamine fully replaces thi- 

 amine in the nutrition of Endoconidiophora funbriota, Mucor raman- 

 nianus, and other fungi and can be converted into thiamine in the cell 

 (141). 



It might be assumed a priori that biosynthesis of thiamine proceeds 

 via a coupling of the two moieties. However, there are some difficul- 

 ties with this simple concept as applied to Neurospora crassa, and 

 Harris (97, 98), on the basis of indirect evidence from nutritional stud- 

 ies, has proposed that thiamine biosynthesis proceeds in this fashion: 



Pyrimidine + unidentified thiazole precursor —> 



thiaminelike intermediate -» thiamine (1) 



Direct coupling of pyrimidine and thiazole may occur as a minor path- 

 way. 



