[Organization and regulation of the genes for nitrogen fixation in Rhodopseudomonas capsulata]. Progress report, [June 5, 1989--June 4, 1991]
In prior support periods we identified, cloned and sequenced three genes involved in the regulation of nif gene expression in Rhodobacter capsulatus. These were called nifRI, nifR2 and nifR4; they turn out to be homologue of the ntrC, ntrB and ntrA genes of enterobacteria. We subsequently found that mutations in an additional gene, nifR5. render R. capsulatus nif genes constitutive with respect to ammonia. The nifR5 gene was shown to be similar to glnB of enteric bacteria, encoding the regulatory protein PII, and furthering the intersection of the glutamine synthetase adenylylation cascade with the control of nif gene transcription. In pursuit of the mechanism of 0{sub 2} control of nif gene expression, we constructed and analyzed the topology of a small plasmid in R. capsulatus as a function of 0{sub 2} concentration. We also cloned and obtained partial sequence data for two genes encoding the B subunit of DNA gyrase. The nucleotide sequence of the rpoB gene encoding RNA polymerase was nearly completed. A method for isolation of genes expressed differentially, developed for cyanobacteria, was applied successfully to R. capsulatus. Several genes that depend on nifR4 for their transcription were isolated. A transcription start site for a nifA gene was identified and the promoter sequence was analyzed. A physical map of the R calsulatus SB1003 chromosome was prepared, based on pulsed-field electrophoresis of XbaI and AseI fragments and hybridization with a gridded cosmid library, using a device that permits 864 cosmids to be hybridized at one time with a labeled chromosomal fragment.
- Research Organization:
- Chicago Univ., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER13546
- OSTI ID:
- 10166528
- Report Number(s):
- DOE/ER/13546--4; ON: DE92018530
- Country of Publication:
- United States
- Language:
- English
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Organization and regulation of the genes for nitrogen fixation in Rhodopseudomonas capsulata
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59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
AGRICULTURE AND FOOD TECHNOLOGY
BIOCHEMISTRY
DNA HELICASES
DNA SEQUENCING
DNA-CLONING
ELECTROPHORESIS
GENE MUTATIONS
GENE OPERONS
GENE REGULATION
GENE REPRESSORS
GENETIC MAPPING
GENETICS
MOLECULAR BIOLOGY
NITROGEN FIXATION
PRODUCTION
PROGRESS REPORT
RHODOPSEUDOMONAS
RNA POLYMERASES
SPECIES DIVERSITY