Bacterial-type ferredoxin genes in the nitrogen fixation regions of the cyanobacterium Anabaena sp. strain PCC 7120 and Rhizobium meliloti

Mulligan, Martin E.; Buikema, William J.; Haselkorn, Robert

doi:10.1128/jb.170.9.4406-4410.1988

Cited by 80 publications

(36 citation statements)

References 28 publications

(33 reference statements)

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“…The fdxN gene was found between nifB and nifS as it is in Anabaena sp. strain PCC 7120 (36) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

“…The other 5 to 10% of cells are heterocysts that have only photosystem I and therefore evolve no oxygen (40). Additional envelope layers in heterocysts may protect nitrogenase from oxygen (38,39 (8,23,30,33,36,37,42). nifJ is not part of the cluster (4).…”

mentioning

confidence: 99%

“…strain PCC 7120: one large cluster contains nifB, fdxN, nifS, nifU, nifH, nifD, nifK, nifN, nifX, open reading frame 3, nifW, open reading frame 1, open reading frame 2, and fdxH (8,23,30,33,36,37,42). nifJ is not part of the cluster (4).…”

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confidence: 99%

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Characterization of nifB, nifS, and nifU genes in the cyanobacterium Anabaena variabilis: NifB is required for the vanadium-dependent nitrogenase

Lyons

Thiel

1995

J Bacteriol

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Anabaena variabilis ATCC 29413 is a heterotrophic, nitrogen-fixing cyanobacterium containing both a Mo-dependent nitrogenase encoded by the nif genes and V-dependent nitrogenase encoded by the vnf genes. The nifB, nifS, and nifU genes of A. variabilis were cloned, mapped, and partially sequenced. The fdxN gene was between nifB and nifS. Growth and acetylene reduction assays using wild-type and mutant strains indicated that the nifB product (NifB) was required for nitrogen fixation not only by the enzyme encoded by the nif genes but also by the enzyme encoded by the vnf genes. Neither NifS nor NifU was essential for nitrogen fixation in A. variabilis.Anabaena spp. are filamentous cyanobacteria capable of fixing dinitrogen in specialized morphologically distinct cells called heterocysts (18,41). Under diazotrophic growth conditions, vegetative cells compose 90 to 95% of the cells in a filament and contain both photosystems I and II. The other 5 to 10% of cells are heterocysts that have only photosystem I and therefore evolve no oxygen (40). Additional envelope layers in heterocysts may protect nitrogenase from oxygen (38, 39).Many nif genes have been identified in Anabaena sp. strain PCC 7120: one large cluster contains nifB, fdxN, nifS, nifU, nifH, nifD, nifK, nifN, nifX, open reading frame 3, nifW, open reading frame 1, open reading frame 2, and fdxH (8,23,30,33,36,37,42). nifJ is not part of the cluster (4). The nifB-fdxNnifS-nifU operon is interrupted by a 55-kb insertion in fdxN, and the nifD gene has an 11-kb insertion, both of which are excised during heterocyst differentiation (19,20). The heterocyst ferredoxin gene of Anabaena sp. strain PCC 7120, fdxH, is downstream of the other characterized nif genes in the cluster (8). The nif genes of A. variabilis ATCC 29413 that are the homologs of the nif genes of Anabaena sp. strain PCC 7120 have been cloned and mapped (24), and the 11-kb excision element, but not the 55-kb excision element, has been found in that nif cluster (9).Besides the nif genes that encode nitrogenase 1, which requires a Mo cofactor, Anabaena variabilis also contains vnf genes that encode nitrogenase 2, which requires a V cofactor (53). Nitrogenases that do not require Mo were first described in Azotobacter vinelandii, which has nitrogenase 1, nitrogenase 2, and nitrogenase 3. Nitrogenase 3, which requires only Fe in the cofactor, is encoded by the anf genes (6, 10, 27). The vnf and anf systems of A. vinelandii do not have homologs of all the genes of the nif system. Known vnf and anf genes include vnfDGK, homologous to nifDK; vnfEN, homologous to nifEN; vnfA, homologous to nifA; and anfHDGK, homologous to nif HDK (6). The nifB, nifS, nifU, nifM, and nifV genes are required for the activity of all three nitrogenases of A. vinelandii (28,29). The vnfEN genes may also function in the anf system (6). The vnf-and anf-encoded nitrogenases are repressed by Mo and have the ability to reduce acetylene not only to ethylene but also to ethane, which is one criterion for the presence of these altern...

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“…The fdxN gene was found between nifB and nifS as it is in Anabaena sp. strain PCC 7120 (36) (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Characterization of nifB, nifS, and nifU genes in the cyanobacterium Anabaena variabilis: NifB is required for the vanadium-dependent nitrogenase

Lyons

Thiel

1995

J Bacteriol

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“…M98808; Anabae: Anabaena sp. (25,26). For maximum homology of the C. maltosa protein, two frameshifted regions of the published nucleotide sequence (reference 44, X05459) were corrected, inserting a G after A223 and deleting G425.…”

Section: Resultsmentioning

confidence: 99%

SPL1-1, a Saccharomyces cerevisiae mutation affecting tRNA splicing

Kolman

Söll

1993

J Bacteriol

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A genetic approach was used to isolate and characterize Saccharomyces cerevisiae genes affecting tRNA processing. Three mutants were isolated which were able to process and utilize splicing-deficient transcripts from inactivated Schizosaccharomyces pombe suppressor tRNA genes. Extragenic recovery of suppressibility was verified by the suppression of nonsense mutations in LEU2, HIS4, and ADE1. One mutant, SPL1-1, was chosen for detailed analysis on the basis of its increased synthesis of mature suppressor tRNA over wild-type cell levels as determined by Northern (RNA) analysis. This mutant exhibited strong suppression exclusively with the defective tRNA gene used in the mutant selection. Genetic analysis revealed that a single, dominant, haplo-lethal mutation was responsible for the suppression phenotype. The mutation mapped on chromosome III to an essential 1.5-kb open reading frame (L. S. Symington and T. D. Petes, Mol. Cell. Biol. 8:595-604, 1988), recently named NFS1 (S. G. Oliver et al., Nature [London] 357:38-46, 1992), located adjacent (centromere proximal) to LEU2.

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“…After rearrangement, the contiguous nifHDK genes in heterocysts are cotranscribed in a single operon (20), and the excised nifD element DNA remains as a stable circular molecule. The second developmentally regulated site-specific recombination system comprises a 55-kbp element residing within the fdxN gene in vegetative cell chromosomes (14,15,41). Recombination within short direct repeat sequences, distinct from the nifD recombination sites, results in the deletion of this element from heterocyst chromo-somes.…”

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confidence: 99%

Developmental rearrangement of cyanobacterial nif genes: nucleotide sequence, open reading frames, and cytochrome P-450 homology of the Anabaena sp. strain PCC 7120 nifD element

et al. 1990

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An 11-kbp DNA element of unknown function interrupts the nifD gene in vegetative cells of Anabaena sp. strain PCC 7120. In developing heterocysts the niJD element excises from the chromosome via site-specific recombination between short repeat sequences that flank the element. The nucleotide sequence of the niJp-proximal half of the element was determined to elucidate the genetic potential of the element. Four open reading frames with the same relative orientation as the nijD element-encoded xisA gene were identified in the sequenced region. Each of the open reading frames was preceded by a reasonable ribosome-binding site and had biased codon utilization preferences consistent with low levels of expression. Open reading frame 3 was highly homologous with three cytochrome P-450 w-hydroxylase proteins and showed regional homology to functionally significant domains common to the cytochrome P-450 superfamily. The sequence encoding open reading frame 2 was the most highly conserved portion of the sequenced region based on heterologous hybridization experiments with three genera of heterocystous cyanobacteria.Anabaena sp. strain PCC 7120 is an oxygen-evolving photoautotroph that is capable of simultaneous photosynthesis and nitrogen fixation. This strain is a well-studied representative of a class of filamentous cyanobacteria that protect nitrogenase from oxygen inactivation by sequestering the enzyme in specialized nitrogen-fixing cells called heterocysts.

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Bacterial-type ferredoxin genes in the nitrogen fixation regions of the cyanobacterium Anabaena sp. strain PCC 7120 and Rhizobium meliloti

Cited by 80 publications

References 28 publications

Characterization of nifB, nifS, and nifU genes in the cyanobacterium Anabaena variabilis: NifB is required for the vanadium-dependent nitrogenase

Characterization of nifB, nifS, and nifU genes in the cyanobacterium Anabaena variabilis: NifB is required for the vanadium-dependent nitrogenase

SPL1-1, a Saccharomyces cerevisiae mutation affecting tRNA splicing

Developmental rearrangement of cyanobacterial nif genes: nucleotide sequence, open reading frames, and cytochrome P-450 homology of the Anabaena sp. strain PCC 7120 nifD element

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