TABLE 12.

PTS fusion proteins that contain only PTS protein domains

Domain fusionOccurrence of domain fusion in PTS enzyme II complex familya
GlcFruLacGutbGatManAscDhac
Domain fusion combinations that were found
    EI-IIA1
    HPr-IIA3
    IIA-HPr102
    HPr-EI-IIA7
    IIA-HPr-EI8103d
    IIA54101762025814726
    IIB15268125564542
    IIC730981631834947
    IID83
    IIAB284
    IIBA1
    IIBC753716
    IICB802187
    IICDe2
    IIABC447
    IIACB3
    IIBCA564
    IICBA3615
Domain fusion combinations that were not found
    EI-HPr
    HPr-EI
    IIA-EI
    EI-HPr-IIA
    EI-IIA-HPr
    HPr-IIA-EI
    IIA-EI-HPr
    IIAC
    IIBAC
    IICA
    IICAB
  • a Glc, Fru, Lac, Gut, Gat, Man, Asc, and Dha indicate the glucose, fructose, lactose, glucitol, galactitol, mannose, ascorbate, and dihydroxyacetone PTS families, respectively. Numbers indicate the numbers of each domain found in the 106 bacterial species (from Tables 7 and 9) that possess PTS homologues. The domain order is as indicated in the first column.

  • b Only in the Gut family is the transmembrane IIC domain split into two polypeptide chains, IIB-IIC1 (GutE; four to five TMSs) and IIC2 (GutA; three TMSs). This unusual arrangement is found in all IIBC homologues except Chloroflexus auranticus, where IIBC1 is split into IIB and IIC1. The complete genome of C. auranticus was not available at the time of our analyses. One organism, Lactobacillus johnsonii, has an orphan IIAGut, while three organisms, Enterococcus faecalis, Lactobacillus plantarum, and Propionibacterium acnes, have a complete glucitol PTS plus an extra IIAGut. Only L. plantarum and Salmonella enterica serovar Typhimurium have two complete enzyme II complexes in the glucitol family.

  • c In the Dha family, the DhaM, DhaL, and DhaK proteins correspond to the IIADha, IIBDha, and IICDha proteins, respectively.

  • d Only one organism, Desulfovibrio vulgaris, possesses a full-length IIADha-HPr-EI fusion, while in two organisms, E. coli and S. flexneri, the C-terminal region of EI is truncated.

  • e The IID domain in the Man family was found fused to IIC in the order IICD but was not present in any other fusion combination.