A Hypothetical Protein Coupled to PEP synthase

1. First, the red genes numbered 1 (often called ydiA) are essentially uncharacterized and probably play a role associated with the PEP synthase or PEP.
   
   
2. Second, note the coupling between the PEP synthase and the blue genes numbered 3 with the function Phospho-2-dehydro-3-deoxyheptonate aldolase (EC 2.5.1.54). This couples PEP synthesis to chorismate synthesis (which takes PEP as input).

Microbiology. 2004 Nov;150(Pt 11):3571-90.

    Comparative genomics of the KdgR regulon in Erwinia chrysanthemi
    3937 and other gamma-proteobacteria.

    Rodionov DA, Gelfand MS, Hugouvieux-Cotte-Pattat N.

    In the plant-pathogenic enterobacterium Erwinia chrysanthemi,
    almost all known genes involved in pectin catabolism are
    controlled by the transcriptional regulator KdgR. In this study,
    the comparative genomics approach was used to analyse the KdgR
    regulon in completely sequenced genomes of eight enterobacteria,
    including Erw. chrysanthemi, and two Vibrio species. Application
    of a signal recognition procedure complemented by operon structure
    and protein sequence analysis allowed identification of new
    candidate genes of the KdgR regulon. Most of these genes were
    found to be controlled by the cAMP-receptor protein, a global
    regulator of catabolic genes. At the next step, regulation of
    these genes in Erw. chrysanthemi was experimentally verified using
    in vivo transcriptional fusions and an attempt was made to clarify
    the functional role of the predicted genes in pectin
    catabolism. Interestingly, it was found that the KdgR protein,
    previously known as a repressor, positively regulates expression
    of two new members of the regulon, phosphoenolpyruvate synthase
    gene ppsA and an adjacent gene, ydiA, of unknown function. Other
    predicted regulon members, namely chmX, dhfX, gntB, pykF, spiX,
    sotA, tpfX, yeeO and yjgK, were found to be subject to classical
    negative regulation by KdgR. Possible roles of newly identified
    members of the Erw. chrysanthemi KdgR regulon, chmX, dhfX,
    gntDBMNAC, spiX, tpfX, ydiA, yeeO, ygjV and yjgK, in pectin
    catabolism are discussed. Finally, complete reconstruction of the
    KdgR regulons in various gamma-proteobacteria yielded a metabolic
    map reflecting a globally conserved pathway for the catabolism of
    pectin and its derivatives with variability in transport and
    enzymic capabilities among species. In particular, possible
    non-orthologous substitutes of isomerase KduI and a new
    oligogalacturonide transporter in the Vibrio species were
    detected.

    PMID: 15528647