Biomaterial Database

Oxygen regulation of expression of nitrogen fixation genes in Rhizobium meliloti. 1994

P G Agron, and E K Monson, and G S Ditta, and D R Helinski

Dept. of Biology, University of California, San Diego, La Jolla 92093-0634.

The sensor kinase FixL and the response regulator FixJ induce the expression of the nitrogen fixation genes of Rhizobium meliloti in response to microaerobiosis, which is a characteristic feature of the plant root nodule interior where the bacteria fix nitrogen. The kinase activity of a purified, soluble derivative of the membrane-bound hemoprotein FixL, designated FixL*, is stimulated under low oxygen conditions, thus increasing FixJ-phosphate levels. FixJ-phosphate is a potent transcriptional activator of the nifA and fixK genes, the products of which, in turn, induce the expression of most if not all of the remaining nitrogen fixation genes. FixL* and FixL*-phosphate also dephosphorylate FixJ-phosphate, and this activity is depressed by low oxygen concentrations. In the current model, gene expression is reciprocally coordinated by the kinase and phosphatase activities of FixL according to changes in oxygen tension.

UI	MeSH Term	Description	Entries
D009586	Nitrogen Fixation	The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.	Diazotrophy,Diazotrophic Activity,Dinitrogen Fixation,N2 Fixation,Activities, Diazotrophic,Activity, Diazotrophic,Diazotrophic Activities,Fixation, Dinitrogen,Fixation, N2,Fixation, Nitrogen
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011401	Promoter Regions, Genetic	DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.	rRNA Promoter,Early Promoters, Genetic,Late Promoters, Genetic,Middle Promoters, Genetic,Promoter Regions,Promoter, Genetic,Promotor Regions,Promotor, Genetic,Pseudopromoter, Genetic,Early Promoter, Genetic,Genetic Late Promoter,Genetic Middle Promoters,Genetic Promoter,Genetic Promoter Region,Genetic Promoter Regions,Genetic Promoters,Genetic Promotor,Genetic Promotors,Genetic Pseudopromoter,Genetic Pseudopromoters,Late Promoter, Genetic,Middle Promoter, Genetic,Promoter Region,Promoter Region, Genetic,Promoter, Genetic Early,Promoter, rRNA,Promoters, Genetic,Promoters, Genetic Middle,Promoters, rRNA,Promotor Region,Promotors, Genetic,Pseudopromoters, Genetic,Region, Genetic Promoter,Region, Promoter,Region, Promotor,Regions, Genetic Promoter,Regions, Promoter,Regions, Promotor,rRNA Promoters
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D006420	Hemeproteins	Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)	Hemeprotein,Heme Protein,Heme Proteins,Protein, Heme,Proteins, Heme
D000071677	Histidine Kinase	A member of the transferase superfamily of proteins. In the activated state, protein-histidine kinase autophosphorylates at a histidine residue, subsequently transferring high-energy phosphoryl groups to an aspartate residue of the response-regulator domain, which results in a conformational shift in the effector domain. Histidine kinases mediate signal transduction in a wide range of processes involving cellular adaptation to environmental stress.	Histidine Protein Kinase,Histone H4 Histidine Kinase,Protein Histidine Pros-Kinase,Protein Kinase (Histidine), Pros-Kinase,Protein-Histidine Kinase,Protein-Histidine Pros-Kinase,Protein-Histidine Tele-Kinase,Sensor Histidine Kinase,Histidine Kinase, Sensor,Histidine Pros-Kinase, Protein,Kinase, Histidine,Kinase, Histidine Protein,Kinase, Protein-Histidine,Kinase, Sensor Histidine,Pros-Kinase, Protein Histidine,Pros-Kinase, Protein-Histidine,Protein Histidine Kinase,Protein Histidine Pros Kinase,Protein Histidine Tele Kinase,Protein Kinase, Histidine,Tele-Kinase, Protein-Histidine
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D016962	Sinorhizobium meliloti	A species of gram-negative, aerobic bacteria that causes formation of root nodules on some, but not all, types of sweet clover, MEDICAGO SATIVA, and fenugreek.	Ensifer meliloti,Rhizobium meliloti
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In