Characterization of genes for a second Mo-dependent nitrogenase in the cyanobacterium Anabaena variabilis

Thiel, Teresa; Lyons, Eilene M.; Erker, James C.

doi:10.1128/jb.179.16.5222-5225.1997

Cited by 71 publications

(66 citation statements)

References 39 publications

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“…2I). However, the strain could grow under this condition, probably because of the presence of the alternative nitrogenase present in vegetative cells (27). Thus, the inhibition of heterocyst formation in Anabaena by CcbP and CaM was likely to result from Ca 2ϩ sequestration.…”

Section: Resultsmentioning

confidence: 97%

CcbP, a calcium-binding protein from Anabaena sp. PCC 7120, provides evidence that calcium ions regulate heterocyst differentiation

Zhao

Shi

Zhao

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Although it is known that calcium is a very important messenger involved in many eukaryotic cellular processes, much less is known about calcium's role in bacteria. CcbP, a Ca 2؉ -binding protein, was isolated from the heterocystous cyanobacterium Anabaena sp. PCC 7120, and the ccbP gene was cloned and inactivated. In the absence of combined nitrogen, inactivation of ccbP resulted in multiple contiguous heterocysts, whereas overexpression of ccbP suppressed heterocyst formation. Calmodulin, which is not present in Anabaena species, could also suppress heterocyst formation in both Anabaena sp. PCC 7120 and Anabaena variabilis. HetR induction upon nitrogen step-down was slow in the strain overexpressing ccbP. It has been demonstrated that [Ca 2ϩ ] i is tightly regulated in some bacteria (6), and there is evidence indicating that calcium is critical to some bacterial cellular processes such as sporulation of Bacillus (7), chemotaxis of Escherichia coli (8), and heterocyst differentiation of cyanobacteria (9). Heterocyst development may represent one of the earliest examples of pattern formation in evolution (10). Heterocysts are specialized cells for nitrogen fixation of some filamentous cyanobacteria (11)(12)(13)(14). When heterocystous cyanobacteria are subjected to nitrogen step-down, some vegetative cells differentiate and become heterocysts. Many genes are specifically involved in heterocyst differentiation. The genes that are required for initiation of cell differentiation include ntcA (15, 16) and hetR (17). HetR is a serine-type protease that plays an important role in heterocyst formation (18).Evidence obtained by manipulating extracellular calcium concentration and by using inhibitors of Ca 2ϩ -binding proteins suggested that Ca 2ϩ could be involved in heterocyst differentiation (9). Here we describe a Ca 2ϩ -binding protein, CcbP, from Anabaena sp. PCC 7120. Our study shows that free calcium accumulates in differentiating cells and mature heterocysts, correlated with a drop in the level of the Ca 2ϩ -binding protein.The free Ca 2ϩ concentration appears to be critical for the differentiation process. Materials and MethodsThe following protocols can be found in Supporting Text, which is published as supporting information on the PNAS web site: growth of the strains of Anabaena; isolation of the Ca 2ϩ -binding protein CcbP; isolation of the ccbP gene from total genomic DNA; expression of recombinant ccbP in Escherichia coli; construction of plasmids for inactivation of the ccbP gene, for copper-regulated expression of ccbP, for copper-regulated expression of rat calmodulin (CaM) gene, for ccbP promoter regulation of GFP expression, and for expression of obelin, a reporter for the level of free Ca 2ϩ .Assays for Ca 2؉ -Binding Proteins. 45 Ca 2ϩ overlay assay was performed as follows: Proteins were first separated by SDS͞PAGE and then transferred to a poly(vinylidene difluoride) membrane. It was then washed three times with buffer C (20 mM Tris⅐HCl, pH 7.2͞5 mM MgCl 2 ͞60 mM KCl͞10 mM imidazole). The memb...

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Section: Resultsmentioning

confidence: 97%

CcbP, a calcium-binding protein from Anabaena sp. PCC 7120, provides evidence that calcium ions regulate heterocyst differentiation

Zhao

Shi

Zhao

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…It has been suggested that the enzyme is located in the thylakoid membranes of heterocysts (48), while others reported its presence in both the vegetative cells and heterocysts and a particular association with the cytoplasmic membrane (88,116,160). There is a diversity in the number of nitrogenases in a single nitrogen-fixing cyanobacterial strain, ranging from one in, e.g., Anabaena strain PCC 7120 and Nostoc strain PCC 73102 to at least three different nitrogenases in A. variabilis (98,99,195,197,198). However, since no study has addressed the question of putatively several uptake hydrogenases in a single strain, the pattern(s) of uptake hydrogenase cellular and subcellular localization might be different for different strains under different environmental conditions.…”

Section: Cyanobacterial Uptake Hydrogenasesmentioning

confidence: 99%

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Tamagnini

Axelsson

Lindberg

et al. 2002

Microbiol Mol Biol Rev

462

372

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Cyanobacteria may possess several enzymes that are directly involved in dihydrogen metabolism: nitrogenase(s) catalyzing the production of hydrogen concomitantly with the reduction of dinitrogen to ammonia, an uptake hydrogenase (encoded by hupSL) catalyzing the consumption of hydrogen produced by the nitrogenase, and a bidirectional hydrogenase (encoded by hoxFUYH) which has the capacity to both take up and produce hydrogen. This review summarizes our knowledge about cyanobacterial hydrogenases, focusing on recent progress since the first molecular information was published in 1995. It presents the molecular knowledge about cyanobacterial hupSL and hoxFUYH, their corresponding gene products, and their accessory genes before finishing with an applied aspect—the use of cyanobacteria in a biological, renewable production of the future energy carrier molecular hydrogen. In addition to scientific publications, information from three cyanobacterial genomes, the unicellular Synechocystis strain PCC 6803 and the filamentous heterocystous Anabaena strain PCC 7120 and Nostoc punctiforme (PCC 73102/ATCC 29133) is included

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“…The nif1 cluster is only expressed in heterocysts, even under strictly anaerobic conditions . However, the nif2 cluster, which lacks both the 11-kb and 55-kb elements, is expressed in vegetative cells, but only under anaerobic conditions, and in heterocysts (Thiel et al, , 1997. The vnf cluster codes for an alternative nitrogenase system containing a vanadium cofactor, instead of the usual molybdenum cofactor, and is expressed in the absence of molybdenum, but only in heterocysts (Thiel, 1993(Thiel, , 1996.…”

Section: Heterocyst Developmentmentioning

confidence: 99%