A proteomic view of the facultatively chemolithoautotrophic lifestyle of Ralstonia eutropha H16.
Ralstonia eutropha H16 is an H(2)-oxidizing, facultative chemolithoautotroph. Using 2-DE in conjunction with peptide mass spectrometry we have cataloged the soluble proteins of this bacterium during growth on different substrates: (i) H(2) and CO(2), (ii) succinate and (iii) glycerol. The first and second conditions represent purely lithoautotrophic and purely organoheterotrophic nutrition, respectively. The third growth regime permits formation of the H(2)-oxidizing and CO(2)-fixing systems concomitant to utilization of an organic substrate, thus enabling mixotrophic growth. The latter type of nutrition is probably the relevant one with respect to the situation faced by the organism in its natural habitats, i.e. soil and mud. Aside from the hydrogenase and Calvin-cycle enzymes, the protein inventories of the H(2)-CO(2)- and succinate-grown cells did not reveal major qualitative differences. The protein complement of the glycerol-grown cells resembled that of the lithoautotrophic cells. Phosphoenolpyruvate (PEP) carboxykinase was present under all three growth conditions, whereas PEP carboxylase was not detectable, supporting earlier findings that PEP carboxykinase is alone responsible for the anaplerotic production of oxaloacetate from PEP. The elevated levels of oxidative stress proteins in the glycerol-grown cells point to a significant challenge by ROS under these conditions. The results reported here are in agreement with earlier physiological and enzymological studies indicating that R. eutropha H16 has a heterotrophic core metabolism onto which the functions of lithoautotrophy have been grafted.
Institut für Biologie, Mikrobiologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, Berlin, Germany. edward.schwartz@rz.hu-berlin.de
Edward
E
Schwartz
Birgit
B
Voigt
Daniela
D
Zühlke
Anne
A
Pohlmann
Oliver
O
Lenz
Dirk
D
Albrecht
Alexander
A
Schwarze
Yvonne
Y
Kohlmann
Cornelia
C
Krause
Michael
M
Hecker
Bärbel
B
Friedrich
D052818:Autotrophic Processes / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D020543:Proteome; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001426:Bacterial Proteins; D020543:Proteome