The structure of the hypothetical protein smu.1377c from Streptococcus mutans suggests a role in tRNA modification.

Members of the Sua5_YciO_YrdC protein family are found in both eukaryotes and prokaryotes and possess a conserved alpha/beta twisted open-sheet fold. The Escherichia coli protein YrdC has been shown to be involved in modification of tRNA. The crystal structure of smu.1377c, a hypothetical protein from Streptococcus mutans, has been determined to 2.25 A resolution. From structure analysis and comparison, it is shown that smu.1377c is a member of the Sua5_YciO_YrdC family and that it may play the same role as E. coli YrdC.