The long term goal of this research is to understand the molecular mechanism of the complex developmental process by which Rhizobium meliloti forms symbiotic nitrogen-fixing nodules on the roots of its host alfalfa. Genetic and molecular biological strategies commonly used with Escherichia coli, lately made possible in this system, will be combined with biochemical, immunological and cell physiological techniques in a multidisciplinary approach based on the complementary expertise of two established laboratories.
As specific aims, genetic tools will continue to be developed, including transposon Tn5 derivatives for making operon fusions in vivo, Hfr-like strains for conjugal mapping, """"""""maxicells"""""""" for visualizing proteins, and host-range and conditional phage mutants for improved transduction. Genetic analysis of exopolysaccharide (EPS) required for effective nodulation will also continue, including cloning and characterization of genes, isolation of new mutants and identification of additional loci. Both extracellular products and lipid-bound biosynthetic intermediates of EPS-deficient mutants will be characterized biochemically. Morphological studies will further characterize the atypical """"""""empty"""""""" nodules of EPS mutants, the interaction with plant roots of mutants having altered EPS, and, by immunofluoresence with monoclonal antibodies, the distribution of EPS in nodule tissue. The ability of isolated EPS to restore effective fixation to mutants will be analyzed further. Regulation of symbiotic genes by plant products will be approached by fusion of nodulation operons to easily assayed reporter genes. This system will serve as a model for the developmental interaction of prokaryotic and eukaryotic cells, of which there are many examples in the area of human health. More specifically, this work will help elucidate the mechanism of biological nitrogen fixation in legumes, with immediate relevance to the health-related issues of plant productivity, agronomic energy conservation and provision of nitrogen in the diet.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM031030-07
Application #
3278953
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1982-07-01
Project End
1990-07-31
Budget Start
1988-08-01
Budget End
1989-07-31
Support Year
7
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Type
Schools of Arts and Sciences
DUNS #
City
Cambridge
State
MA
Country
United States
Zip Code
02139
Ghosal, Anubrata; Babu, Vignesh M P; Walker, Graham C (2018) Elevated Levels of Era GTPase Improve Growth, 16S rRNA Processing, and 70S Ribosome Assembly of Escherichia coli Lacking Highly Conserved Multifunctional YbeY Endoribonuclease. J Bacteriol 200:
Budnick, James A; Sheehan, Lauren M; Colquhoun, Jennifer M et al. (2018) Endoribonuclease YbeY Is Linked to Proper Cellular Morphology and Virulence in Brucella abortus. J Bacteriol 200:
Arnold, Markus F F; Shabab, Mohammed; Penterman, Jon et al. (2017) Genome-Wide Sensitivity Analysis of the Microsymbiont Sinorhizobium meliloti to Symbiotically Important, Defensin-Like Host Peptides. MBio 8:
Ghosal, Anubrata; Köhrer, Caroline; Babu, Vignesh M P et al. (2017) C21orf57 is a human homologue of bacterial YbeY proteins. Biochem Biophys Res Commun 484:612-617
Shabab, Mohammed; Arnold, Markus F F; Penterman, Jon et al. (2016) Disulfide cross-linking influences symbiotic activities of nodule peptide NCR247. Proc Natl Acad Sci U S A 113:10157-62
Vercruysse, Maarten; Köhrer, Caroline; Shen, Yang et al. (2016) Identification of YbeY-Protein Interactions Involved in 16S rRNA Maturation and Stress Regulation in Escherichia coli. MBio 7:
Pini, Francesco; De Nisco, Nicole J; Ferri, Lorenzo et al. (2015) Cell Cycle Control by the Master Regulator CtrA in Sinorhizobium meliloti. PLoS Genet 11:e1005232
Price, Paul A; Tanner, Houston R; Dillon, Brett A et al. (2015) Rhizobial peptidase HrrP cleaves host-encoded signaling peptides and mediates symbiotic compatibility. Proc Natl Acad Sci U S A 112:15244-9
De Nisco, Nicole J; Abo, Ryan P; Wu, C Max et al. (2014) Global analysis of cell cycle gene expression of the legume symbiont Sinorhizobium meliloti. Proc Natl Acad Sci U S A 111:3217-24
Penterman, Jon; Abo, Ryan P; De Nisco, Nicole J et al. (2014) Host plant peptides elicit a transcriptional response to control the Sinorhizobium meliloti cell cycle during symbiosis. Proc Natl Acad Sci U S A 111:3561-6

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