Genetic evidence for an interaction of the UbiG O-methyltransferase with UbiX in Escherichia coli coenzyme Q biosynthesis

IS16 is a thiol-sensitive, Q-deficient mutant strain of Escherichia coli. Here, we show that IS16 harbors a mutation in the ubiG gene encoding a methyltransferase required for two O-methylation steps of Q biosynthesis. Complementation of IS16 with either ubiG or ubiX(K-12) reverses this phenotype, suggesting that UbiX may interact with UbiG.