Another CoA Cluster Worth Pondering

Please consider the cluster around dephospho-CoA kinase that seems to occur in numerous organisms.

One cannot help but be struck by the number of genes relating to secretion.
Gene. 1994 Dec 2;150(1):9-15.

    Escherichia coli contains a set of genes homologous to those
    involved in protein secretion, DNA uptake and the assembly of
    type-4 fimbriae in other bacteria.

    Whitchurch CB, Mattick JS.

    A specialised system involved in a diverse array of functions,
    including the biogenesis of fimbriae, protein secretion and DNA
    uptake, has recently been found to be widespread in the
    eubacteria. These systems have in common several sets of related
    genes, including those encoding proteins containing leader
    sequences homologous to that of the type-4 fimbrial subunit
    (prepilin), a prepilin-type leader peptidase, a cytoplasmic
    nucleotide-binding protein, and other proteins located in the
    inner and outer membranes [Hobbs, M. and Mattick, J.S., Mol
    Microbiol. 10 (1993) 233-243]. Here, we show that Escherichia coli
    contains at least nine homologs of this system, and present
    complete sequence data for five of the genes involved (ppdD. hopB,
    hopC, hopD and pshM), as well as for an adjacent gene (nadC),
    which encodes quinolic acid phosphoribosyltransferase. Insertional
    mutagenesis of hopB and hopD failed to reveal any obvious effects
    on cell viability, morphogenesis of M13 phage, conjugative
    transfer of the F plasmid, or protein secretion.

    PMID: 7959070 

Comment from Andrei:

Ross, Not sure I can say much about this either. Secretion (and all related components) is a huge machinery indeed. Part of it is quite conserved but there is a lot of variations and nuances related to specifics of species (I bet more that in a regular metabolic SS). Connection with DPCK is beyond me. DPCK seems to be a housekeeping gene, may not be a subject of any regulation. Therefore it may be just embedded in some uberperons of housekeeping (constitutively expressed) genes? Among genes around it in your cluster: All 2,3, and likely 5 appear to be fimbria-related. Besides, in E.coli DPCK and other fimbria-reated genes are in DIFFERENT operons. DPCK appears in the same operon with yacF (gene 4) I can’t make anything of it. It is very conserved and very coupled, but what is it? I have no idea. Sorry for disappointing. AO