Biochemical effects of formycin B on Xanthomonas oryzae.

Formycin B, an inosine analogue, inhibits the incorporation of radioactive adenosine, uridine and thymidine, but none of formic acid, orotic acid and inorganic phosphoric acid into the cellular nucleic acid of Xanthomonas oryzae. The biochemical effects are readily reversed when formycin B is removed. Cell-free extract from the organism is entirely insensitive to formycin B in respect to phosphorylation of adenosine and thymidine. In consequence, it is likely that formycin B interferes with some process essential to entry of exogenous nucleosides into the cell. The lethal effect of formycin B on the organism is partially overcame by several nucleosides.