Bacterial mannitol-specific phosphotransferase system, Enzyme II complex (EIIMtl)

The Bacterial mannitol-specific phosphotransferase system (PTS), Enzyme II complex (EIIMtl), is a specialized multi-domain protein or complex that mediates the active transport and concomitant phosphorylation of mannitol in various bacterial species [1, 4, 8]. It typically comprises three functional domains: EIIA, EIIB, and EIIC, which may be fused into a single polypeptide (often encoded by the mtlA gene) or exist as separate subunits [3, 11, 27]. The EIIC domain forms the transmembrane channel for mannitol translocation, while the EIIA and EIIB domains participate in a phosphoryl relay that transfers a phosphate group from phosphoenolpyruvate (PEP) to the incoming sugar [23, 27]. Beyond its primary role in carbohydrate metabolism, EIIMtl acts as a sensory and regulatory component, influencing virulence factor expression and biofilm formation in pathogens such as Vibrio cholerae and Staphylococcus aureus [1, 3, 35]. Because the PTS is unique to bacteria and absent in eukaryotes, it is considered a promising target for the development of novel antimicrobial agents designed to disrupt bacterial energy acquisition and pathogenesis [6, 16, 19]. Experimental inhibitors such as N-ethylmaleimide and potassium ferricyanide have been shown to modulate its activity in research settings [2, 7, 30].

Other names

Mannitol-specific PTS Enzyme IIMtlAMannitol permeasePTS system mannitol-specific EIICB componentPTS system mannitol-specific EIIA componentEnzyme IImtlPhosphoenolpyruvate-dependent mannitol-specific phosphotransferase system Enzyme II

The complex facilitates the uptake of extracellular mannitol and its simultaneous phosphorylation to mannitol-1-phosphate using a phosphoryl group derived from phosphoenolpyruvate (PEP), which is transferred through Enzyme I (EI) and HPr to the EIIA, EIIB, and finally to the sugar during transport through the EIIC membrane channel [8, 23, 27].