The bicistronic groESL operon, encoding the Hsp60 and Hsp10 chaperonins, was cloned into an integrative expression vector, pFPN, and incorporated at an innocuous site in the Anabaena sp. strain PCC7120 genome. In the recombinant Anabaena strain, the additional groESL operon was expressed from a strong cyanobacterial P(psbA1) promoter without hampering the stress-responsive expression of the nat...

Anabaena variabilis ATCC 29413 is a heterotrophic, nitrogen-fixing cyanobacterium that has been reported to fix nitrogen and reduce acetylene to ethane in the absence of molybdenum. DNA from this strain hybridized well at low stringency to the nitrogenase 2 (vnfDGK) genes of Azotobacter vinelandii. The hybridizing region was cloned from a lambda EMBL3 genomic library of A. variabilis, mapped, a...

Genes homologous to those implicated in glutamine synthetase (GS) regulation by protein-protein interaction in the cyanobacterium Synechocystis sp. strain PCC 6803 are conserved in several cyanobacterial sequenced genomes. We investigated this GS regulatory mechanism in Anabaena sp. strain PCC 7120. In this strain the system operates with only one GS inactivation factor (inactivation factor 7A ...

Single-stranded DNA binding (SSB) proteins are essential for all DNA-dependent cellular processes. Typical SSB proteins have an N-terminal Oligonucleotide-Binding (OB) fold, a Proline/Glycine rich region, followed by a C-terminal acidic tail. In the genome of the heterocystous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120, alr0088 and alr7579 are annotated as coding for SSB, but a...

Pyruvate:ferredoxin (flavodoxin) oxidoreductase (PFO, EC 1.2.7.1) catalyses the oxidative cleavage of pyruvate and coenzyme A to acetylcoenzyme A and CO2 with the simultaneous reduction of ferredoxin or flavodoxin. PFO occurs in anaerobes and in some aerobic archaea and bacteria. For cyanobacteria, activity measurements indicated the occurrence of PFO in heterocystous forms. The completely sequ...

Heterotrophic bacteria are commonly found in close associations with photosynthetic cyanobacteria in aquatic ecosystems. Some of these associations can be speciesspecific and mutualistic, resulting in optimal growth and nitrogen-fixing potential for the cyanobacteria. A two-membered culture, consisting of a heterotrophic, epibiotic bacterium attached to an Anabaena sp. was studied in the work r...

Anabaena sp. strain PCC 7120 adapts to deprivation of fixed nitrogen by undergoing physiological and genetic changes that include formation of N2-fixing heterocysts. Whether or not certain of the genes involved are interdependently expressed has been studied.

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 c...

Geosmin has often been associated with off-flavor problems in drinking water with Anabaena sp. as the major producer. Rapid on-site detection of geosmin-producers as well as geosmin is important for a timely management response to potential off-flavor events. In this study, quantitative polymerase chain reaction (qPCR) methods were developed to detect the levels of Anabaena sp. and geosmin, res...