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Description (originally from EcoCyc[1][2]) EIIBCFrw

Comments (originally from EcoCyc[1][2]) FrwCBD PtsA, a putative PTS permease, belongs to the functional superfamily of the phosphoenolpyruvate (PEP)-dependent, sugar transporting phosphotransferase system (PTS). The PTS transports and simultaneously phosphorylates its sugar substrates in a process called group translocation. FrwCBD PtsA presumably takes up unknown exogenous sugars, releasing the phosphate esters into the cell cytoplasm in preparation for metabolism [3] .

FrwC (Enzyme IICFrw), FrwB (Enzyme IIBFrw), FrwD (Enzyme IIBFrw') and PtsA (an Enzyme I-Enzyme IIAFrw hybrid protein) are all encoded within the frw gene cluster. The Frw proteins and protein domains are homologous to constituents of the fructose Enzyme II complexes. The frw gene cluster also encodes several enzymes concerned with anaerobic carbon metabolism. At least two operons are present in the frw gene cluster, but the operon structures are not clearly defined. The overall PTS-mediated phosphoryl transfer reaction, requiring the two general energy coupling proteins of the PTS, Enzyme I and HPr, as well as the three domains of the Enzyme II complex is:

PEP --> Enzyme I(his~~P)

--> HPr(his~~P) --> IIA(his~~P) -->

IIB(cys~~P) -(IIC)-> sugar-P.

Nothing is known regarding the expression of the frw gene cluster or its regulation.


  1. 1.0 1.1 EcoCyc (release 10.6; 2007) Keseler, IM et al. (2005) Nucleic Acids Res. 33(Database issue):D334-7
  2. 2.0 2.1 EcoCyc (release 11.1; 2007) Keseler, IM et al. (2005) Nucleic Acids Res. 33(Database issue):D334-7
  3. Postma, PW et al. (1993) Phosphoenolpyruvate:carbohydrate phosphotransferase systems of bacteria. Microbiol. Rev. 57 543-94 PubMed

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