Sunday, October 17, 2010

More Part II: Survey of other Proteobacteria

Dichelobacter is competent; it's a gamma.

Natural competence has been investigated in the beta- and epsilonproteobacteria, especially in Neisseria and Helicobacter.  However, although much is now known about their mechanisms of DNA uptake and the proteins responsible, little is known about regulation.

Betaproteobacteria:  Neisseria meningitidis and gonohorrhoeae:  DNA uptake requires many of the same genes as in H. influenzae.  No homologs of CRP or Sxy.  Competence appears to be constitutive under typical laboratory culture conditions - transformation frequencies are typically high throughout growth in broth and in cells grown on agar plates.  Is piliation also constitutive?  Mutation hunts for genes needed for transformation have not identified any regulatory genes (refs?).  One PTS gene involved (find ref)?  Any in vivo hints that regulation exists?  (discussion material?)

Eikenella is a competent Neisseriaceae (Tonjum 1985); she later cites this paper as evidence that competence is coupled to expression of T4P.  Also Kingella (Weir and Marrs 1992).
  • Burkholderia and Ralstonia(family Burkholderaceae)  Thongdee et al 2008, B. thailandensis and B. pseudomallei.  Transformation in defined medium over 6-36 hr with DNA.  Ralstonia (Bertolla et al 1997)  Transformation highest at OD=.8.
  • Thiobacillus (Family Hydrogenophilaceae - other genus Hydrophilus)  Log phase cells put on agar with DNA for several hours. Yankofsky et al 1983
  • Achromobacter (Family Alkaliginaceae, also Bordetella (not competent?))  Transformation on agar plates, not quantitative, no regulatory info. (Juni & Heym 1980)
  • Methylobacterium organophilum (O'Connor et al. 1977)  High TF, sharp peak of competence at end of log phase.
  • Bradyrhizobium
  • Agrobacterium tumefaciens
  • No transformable species have been described. 

  • Helicobacter (Baltrus and Guillemin 2007 did a time course.  Although phases of growth were not well defined (by the authors/experiments), measures of transformation (not frequencies but something weird) rose as culture growth slowed in late log, fell , and then rose and fell again after cfu/ml had begun to decrease.  They also looked at two other strains.  But I'm not sure that their measures mean much at all.  (RRResearch post?)   In another paper (Israel 2000?) Transformation frequencies rose and fell as cultures became dense.  Tells us that competence is regulated by growth conditions, but no details. 
  • Look at a new paper (PLoS Pathogens 2010).
  • Campylobacter:  Find the info Erin sent.
Beyond the Proteobacteria but still Gram negative (Acidobacteria, Aquificae):
  • No transformable species have been described (but Aquifex has PilT).

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