Mannose uptake and phosphorylation in Escherichia coli is catalyzed by the phosphoenolpyruvate:glycose phosphotransferase system (PTS). The mannose-specific complex of the PTS, designated H1MaI, comprises lipid and two membrane proteins, ll-AM and II-BMaI. The proteins are encoded by ptsM, located at "40 minutes on the E. coli chromosome. A different genetic marker, pel, maps with ptsM, and is required for X DNA penetration of the cytoplasmic membrane. Earlier studies suggested that bothpel function and ll-Bm are encoded by the same gene, while a different gene (also in ptsM) encodes II-AM". In the present studies, a ptsM done, pCS13, was isolated from an E. colU Hindml gene bank in pBR322 and restored both mannose fermentation and pelt function to ptsM mutants defective in II-BMaI. Subclones of pCS13 show that (i) two distinct genes, manY and manZ, encode thepel function and the II-BMa`protein, respectively; (ii) each gene may have its own promoter; (iii) whereas the protein encoded by manY (Pel) alone seems sufficient for X sensitivity, all three gene products are required for mannose fermentation, transport of the mannose analogue 2-deoxyglucose, and phosphorylation of the latter by cytoplasmic membranes. Thus, Pel is required for function of the HIMan complex. The efficiency of the complex may depend on the ratio of Pel to 11Man.The phosphoenolpyruvate:glycose phosphotransferase system (PTS) catalyzes the translocation of its sugar substrates across the bacterial membrane concomitant with their phosphorylation (1-3). The PTS consists of two cytoplasmic phosphorylated carrier proteins, enzyme I and HPr (which are not sugar specific) and a number of sugar-specific membrane-associated proteins, called enzyme II complexes. Phosphoryl group transfer occurs in the following sequence: phosphoenolpyruvate -* enzyme I --HPr --enzyme II sugar.Two enzyme II complexes catalyze glucose translocation across the Escherichia coli membrane (4, 5). One, designated IIGlc, is specific for glucose and methyl glucosides. The second complex, IIMan, the subject of this report, comprises two membrane-associated proteins II-AMan and II-BMan, and phosphorylates glucose, mannose, and their analogues, such as 2-deoxyglucose (4-7).The concept of two proteins in the IIMan complex was based on early biochemical data (7). By contrast, genetic mapping suggested only a single locus for ptsM (8), at =40 minutes on the E. coli map. Another mutation in this region, called pel, resulted in resistance to penetration of the bacterial inner membrane by X DNA (9, 10). pel appeared to be closely related to ptsM since strains bearing mutations in pel were unable to ferment mannose (although only 30% of the strains unable to ferment mannose were insensitive to X phage).Recent work in this and other laboratories (refs. 11 and 12; P. Saris and E. T. Palva, personal communication) has shown thatptsM contains two structural genes-one encodes II-AMan (manX), and the other encodes II-BMan (manZ). Transcription occurs from manX through manZ with a str...