Rhizobium-leguminous plant symbioses are unique associations in which both the bacteria and the plant undergo complex metabolic and morphological changes to reduce atmospheric dinitrogen to organic forms of nitrogen. The nitrogen-fixation process has a high energy demand, implying that the plant's microsymbionts, called bacteroids, efficiently generate energy from compounds supplied by the plant. Proteo-genomics (the integration of transcriptomics and proteomic technologies) is being applied to elucidate the metabolic and regulatory activities of the microsymbionts and the plant nodule cells. The bacteroid expresses a dominant and elaborate protein network for nitrogen and carbon metabolism, which is closely dependent on the plant, supplied metabolites and seems aptly supported by a selective group of bacteroid transporter proteins. However, they seem to lack a defined fatty acid and nucleic acid metabolism. Interestingly, the proteins related to protein synthesis, scaffolding and degradation were among the most predominant spots of the bacteroid proteome. Proteo-genomic analysis clearly showed the inter-connection between several metabolic pathways that meet the needs of the bacteroid. Metabolomic analyses confirm the metabolic profiles identified by proteo-genomics.

• Is nitrogen the new carbon? (Sep 2009)

• Wiliam T. Kemper Fellowship for Excellence in Teaching (2000)
• Associate Chair, Division of Biochemistry (2005-Present)
• Director of Undergraduate Education, Division of Biochemistry (2005-Present)

(2000-Present)

Sarma AD, Oehrle NW and Emerich DW. Plant protein isolation and stabilization for enhanced resolution of two-dimensional polyacrylamide gel electrophoresis. Analytical Biochemistry 2008;379(2):192-195.

Oehrle NW, Sarma AD, Waters JK and Emerich DW. Proteomic analysis of soybean nodule cytosol. Phytochemistry 2008;69(13):2426-2438.

Zhao S, Chen L, Ganapathy A, Wan XF, Brechenmacher L, Tao N, Emerich D, Stacey G and Xu D. Development and assessment of scoring functions for protein identification using PMF data. Electrophoresis 2007;28(5):864-870.

Ramirez-Trujillo JA, Encarnacion S, Salazar E, Garcia De Los Santos A, Dunn MF, Emerich DW, Calva E and Hernandez-Lucas I. Functional characterization of the Sinorhizobium meliloti acetate metabolism genes aceA, SMc00767, and glcB. Journal of Bacteriology 2007;189(16):5875-5884.

Giraud E, Moulin L, Vallenet D, Barbe V, Cytryn E, Avarre JC, Jaubert M, Simon D, Cartieaux F, Prin Y, Bena G, Hannibal L, Fardoux J, Kojadinovic M, Vuillet L, Lajus A, Cruveiller S, Rouy Z, Mangenot S, Segurens B, Dossat C, Franck WL, Chang WS, Saunders E, Bruce D, Richardson P, Normand P, Dreyfus B, Pignol D, Stacey G, Emerich D, Vermeglio A, Medigue C and Sadowsky M. Legumes symbioses: Absence of Nod genes in photosynthetic bradyrhizobia. Science 2007;316(5829):1307-1312.

Cytryn EJ, Sangurdekar DP, Streeter JG, Franck WL, Chang WS, Stacey G, Emerich DW, Joshi T, Xu D and Sadowsky MJ. Transcriptional and physiological responses of Bradyrhizobium japonicum to desiccation-induced stress. Journal of Bacteriology 2007;189(19):6751-6762.

Cytryn EJ, Sangurdekar DP, Streeter JG, Franck WL, Chang WS, Stacey G, Emerich DW, Joshi T, Xu D and Sadowsky MJ. Transcriptional and physiological responses of Bradyrhizobium japonicum to desiccation-induced stress. Journal of Bacteriology 2007;189(24):9150.

Chang WS, Franck WL, Cytryn E, Jeong S, Joshi T, Emerich DW, Sadowsky MJ, Xu D and Stacey G. An oligonucleotide microarray resource for transcriptional profiling of Bradyrhizobium japonicum. Molecular Plant-Microbe Interactions 2007;20(10):1298-1307.

Shah R and Emerich DW. Isocitrate dehydrogenase of Bradyrhizobium japonicum is not required for symbiotic nitrogen fixation with soybean. Journal of Bacteriology 2006;188(21):7600-7608.

Sarma AD and Emerich DW. A comparative proteomic evaluation of culture grown vs nodule isolated Bradyrhizobium japonicum. Proteomics 2006;6(10):3008-3028.

Sarma AD and Emerich DW. Global protein expression pattern of Bradyrhizobium japonicum bacteroids: A prelude to functional proteomics. Proteomics 2005;5(16):4170-4184.

Oehrle N, Shah R, Gentry B and Emerich DW. Rapid, multiphasic attachment of Bradyrhizobium japonicum soybean roots. Symbiosis 2005;39(1):21-26.

Oehrle NW, Green LS, Karr DB and Emerich DW. The HFC/HCFC breakdown product trifluoroacetic acid (TFA) and its effects on the symbiosis between Bradyrhizobium japonicum and soybean (Glycine max). Soil Biology and Biochemistry 2004;36(2):333-342.

Karr DB, Oehrle NW and Emerich DW. Recovery of nitrogenase from aerobically isolated soybean nodule bacteroids. Plant and Soil 2003;257(1):27-33.

Green LS, Waters JK, Ko S and Emerich DW. Comparative analysis of the Bradyrhizobium japonicum sucA region. Canadian Journal of Microbiology 2003;49(4):237-243.

Emerich D. Plant and Soil: preface. Plant and Soil 2003;257(1).

Oehrle NW, Karr DB, Kremer RJ and Emerich DW. Enhanced attachment of Bradyrhizobium japonicom to soybean through reduced root colonization of internally seedborne microorganisms. Canadian Journal of Microbiology 2000;46(7):600-606.

Karr DB, Liang RT, Reuhs BL and Emerich DW. Altered exopolysaccharides of Bradyrhizobium japonicum mutants correlate with impaired soybean lectin binding, but not with effective nodule formation. Planta 2000;211(2):218-226.

Karr DB and Emerich DW. Bradyrhizobium japonicum isocitrate dehydrogenase exhibits calcium-dependent hysteresis. Archives of Biochemistry and Biophysics 2000;376(1):101-108.

Green LS, Li Y, Emerich DW, Bergersen FJ and Day DA. Catabolism of alpha-ketoglutarate by a sucA mutant of Bradyrhizobium japonicum: Evidence for an alternative tricarboxylic acid cycle. Journal of Bacteriology 2000;182(10):2838-2844.