Novel Phosphotransferase System Genes Revealed by Bacterial Genome Analysis: The Complete Complement of pts Genes in Mycoplasma genitalium

The complete sequence of the Mycoplasma genitalium chromosome has recently been determined. We here report analyses of the genes encoding proteins of the phosphoenolpyruvatersugar phosphotransferase system, PTS. These genes encode (1) Enzyme I, (2) HPr, (3) a glucose-specific Enzyme IICBA, (4) an inactive glucose-specific Enzyme IIB, lacking the active site cysteyl residue, and (5) a fructose-specific Enzyme IIABC. Some of the unique features of these genes and their enzyme products are as follows. (1) Each of the genes is encoded within a distinct operon. (2) Both Enzyme I and HPr have basic isoelectric points. (3) The glucose-specific Enzyme IIC bears a centrally located, hydrophilic, 200 amino acyl residue insert that lacks sequence similarity with any protein in the current database. (4) The fructose-specific Enzyme II has a domain order (IIABC), different from those of previously characterized fructose permeases, and its IIA domain more closely resembles the IIA^Ntr protein of Escherichia coli than other fructose-specific IIA domains. The potential significance of these novel features is discussed.