This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gabel, C Articles by Maier, R J Search for Related Content PubMed PubMed Citation Articles by Gabel, C Articles by Maier, R J Agricola Articles by Gabel, C Articles by Maier, R J

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1994 January; 60(1): 141-148

Cytochrome aa3 gene regulation in members of the family Rhizobiaceae: comparison of copper and oxygen effects in Bradyrhizobium japonicum and Rhizobium tropici.

Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218.

ABSTRACT

Dithionite-reduced minus ferricyanide-oxidized difference spectra on membranes from Rhizobium tropici (formerly Rhizobium leguminosarum bv. phaseoli) incubated at progressively lower O2 concentrations showed only a slight concomitant decrease in A603, the alpha-peak of cytochrome aa3. In contrast to previous results on Bradyrhizobium japonicum, R. tropici showed no significant O2-mediated reduction in the level of either coxA transcription or cytochrome aa3 activity (as measured by ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine [TMPD] oxidase) even in the cells incubated at 12.5 microM O2. Bean nodule R. tropici bacteroids contained 65% of the fully aerobic free-living levels of the coxA transcript. Primer extension analyses established the transcription initiation site of the R. tropici coxA genes. Sequence analyses of the regions upstream of the transcription initiation site revealed no homology with previously reported Rhizobiaceae family promoters, including the coxA promoter of B. japonicum. The R. tropici deduced CoxA sequence itself is highly homologous to the B. japonicum and Paracoccus denitrificans CoxA sequences. In both B. japonicum and R. tropici, coxA transcript levels were the same for cells grown with copper (0.02 microM) in the medium or in medium completely devoid of copper. However, a posttranscriptional effect of copper deprivation was observed for both bacteria; difference absorption spectra on membranes from cells grown without copper showed that B. japonicum lacked spectroscopically detectable cytochrome aa3, whereas R. tropici retained approximately 50% of normal cytochrome aa3 levels.

This article has been cited by other articles:

• Marroquí, S., Zorreguieta, A., Santamaría, C., Temprano, F., Soberón, M., Megías, M., Downie, J. A. (2001). Enhanced Symbiotic Performance by Rhizobium tropici Glycogen Synthase Mutants. J. Bacteriol. 183: 854-864 [Abstract] [Full Text]  
• Surpin, M. A., Maier, R. J. (1999). Symbiotic Deficiencies Associated with a coxWXYZ Mutant of Bradyrhizobium japonicum. Appl. Environ. Microbiol. 65: 339-341 [Abstract] [Full Text]  
• Baker, S. C., Ferguson, S. J., Ludwig, B., Page, M. D., Richter, O.-M. H., van Spanning, R. J. M. (1998). Molecular Genetics of the Genus Paracoccus: Metabolically Versatile Bacteria with Bioenergetic Flexibility. Microbiol. Mol. Biol. Rev. 62: 1046-1078 [Abstract] [Full Text]