Organization and regulation of the genes for nitrogen fixation in Rhodopseudomonas capsulata
The research carried out over the past two years with DOE support has led to the elucidation of the complete nucleotide sequence of three genes required for the transcription of the genes for nitrogen fixation in Rhodobacter capsulatus. These genes are called nifR1, nifR2 and nifR4 in R. capsulatus. They were found to be homologous to ntrC, ntrB and ntrA in Klebsiella, respectively. Genetic analysis of ammonia-constitutive (NiF{sup c}) mutants of R. capsulatus, isolated using a nifH::lac fusion, showed that ammonia repression involves components of the adenylylation cascade (e.g., the glnB gene) as in Klebsiella. Oxygen control of nif gene expression was linked to the degree of DNA supercoiling by showing that inhibitors of DNA gyrase prevent nif gene expression. Attempts to relate the degree of supercoiling or of gyrase activity in R. capsulatus to the oxygen level have been inconclusive. The gene encoding the DNA gyrase B subunit of R. capsulatus was cloned. The genes encoding the two large subunits of R. Capsulatus RNA polymerase were cloned, mapped and partially sequenced. The nif genes and the glnA gene are being physically mapped on the R. capsulatus chromosome using pulsed field electrophoresis to separate large segments of the bacterial chromosome. A start was made on the purification of R. capsulatus RNA polymerase. A system for expressing genes in R. capsulatus was applied to nifR4; analogous constructions will be made for nifR1, nifR2 and nifA.
- Research Organization:
- Chicago Univ., IL (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- FG02-86ER13546
- OSTI ID:
- 5132618
- Report Number(s):
- DOE/ER/13546-3; ON: DE90005422
- Country of Publication:
- United States
- Language:
- English
Similar Records
[Organization and regulation of the genes for nitrogen fixation in Rhodopseudomonas capsulata]. Progress report, [June 5, 1989--June 4, 1991]
Organization and regulation of the genes for nitrogen fixation in Rhodopseudomonas capsulata: Progress report, June 5, 1987-June 4, 1988
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
CHROMOSOMES
DNA SEQUENCING
DOCUMENT TYPES
GENE REGULATION
GENE REPRESSORS
GENETIC MAPPING
MAPPING
MICROORGANISMS
NITROGEN FIXATION
NUCLEOPROTEINS
NUCLEOTIDES
ORGANIC COMPOUNDS
PROGRESS REPORT
PROTEINS
RHODOPSEUDOMONAS
STRUCTURAL CHEMICAL ANALYSIS
TRANSCRIPTION FACTORS