Blasticidin crystal structure

The bromide monohydrate was also used71 in establishing the crystal structure of blasticidin S. The dimensions of the unit cell (a =... 

The aminoaqfl-4-aminohexosyl-cytosine group of antibiotics is classified based on chemical structures (Fig. 4.11) each of which contains a cytosine base. Included in this group are blasticidin S, gougerotin, amicetin and bamicetin [46]. These antibiotics are not used therapeutically. However blasticidin S is an important antifungal used on rice crops. Only the crystal structure of blasticidin S bound to the ribosome is available. The chemical structure of blasticidin S resembles that of pep-tidyl-cytidine, although not as closely as puromycin resembles a tyrosylated adenosine (Fig. 4.11). 

In the crystal structure, blasticidin S binds to two sites on the ribosome (Fig. 4.13) and forms base-pairs with Hm G2284 and G2285 Ec 2251 and 2252). These two guanines are almost totally conserved residues of the P-loop, and are known to base pair with the CCA end of tRNA in order to position the P-site substrate in the peptidyl transferase center [47]. 

Fig.4. 13 Blasticidin S. Blasticidin S (purple) base pairs to the P-loop of rRNA (grey). Its guanidinium tail forms hydrogen bonds (dotted lines) to the phosphate and stacks hydrophobically onto the base of Hm A2474, a nucleotide that is protected from chemical modification (green) by blasticidin S. Superimposition of rRNA between crystal structures causes blasticidin S to become superimposed on C74 and C75 (yellow) of the analogue of a CCA end of tRNA. Fig. from [7].

Swaminathan V, Smith JL, Sundaraiiitgam M, Coutsogeorgopoulos C, Kartha G. Crystal and molecular structure of the antibiotic blasticidin S hydrochloride pentahydrate. Biochim Bio-phys Acta 1981 655 335-341. 

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