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The CyAbrB transcription factor Alr0946 regulates the iron superoxide dismutase in Nostoc sp. strain PCC 7120
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry. (Peter Lindblad)
Program of Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry. (Peter Lindblad)
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry. (Peter Lindblad)ORCID iD: 0000-0001-6993-8476
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In the present investigation we analyse the results of induced over-production of the CyAbrB transcription factor Alr0946 in the cyanobacterium Nostoc sp. PCC 7120 with special focus on its effects on FeSOD. With gel based quantitative proteomics the induced over-expression of Alr0946 was shown to influence the abundance of at least 25 proteins. One of the proteins with a significant lower abundance was FeSOD, one of two types of superoxide dismutases in Nostoc sp. PCC 7120. The change in protein abundance was also followed by lower transcript as well as activity levels. Purified Alr0946 from Nostoc sp. PCC 7120 was shown to interact with the promoter region of alr2938, encoding FeSOD, indicating a transcriptional regulation of FeSOD by Alr0946. The Alr0946 over-expression strain showed a bleaching phenotype with lower growth rate and truncated filaments already two days after induction of over-expression. The phenotype was even more pronounced when illumination was increased from 35 to 125 μmol m-2s-1. This is in line with an increased need of FeSOD during a stronger oxidative stress. The results indicate that Alr0946 is involved in regulation of stress responses and that FeSOD has a specific and important function in the oxidative stress tolerance of the multicellular cyanobacterium Nostoc sp. PCC 7120.

Keyword [en]
Nostoc sp. PCC 7120, FeSOD, Alr0946, transcription factor, CyAbrB
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:uu:diva-110862OAI: oai:DiVA.org:uu-110862DiVA: diva2:278638
Available from: 2009-11-27 Created: 2009-11-27 Last updated: 2016-04-21
In thesis
1. Maturation and Regulation of Cyanobacterial Hydrogenases
Open this publication in new window or tab >>Maturation and Regulation of Cyanobacterial Hydrogenases
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Accelerated global warming plus an increasing need for energy is an equation not easily solved, thus new forms of sustainable energy production are urgently requested. In this context hydrogen production based on a cyanobacterial system offers an environmentally friendly alternative for energy capture and conversion. Cyanobacteria can produce hydrogen gas from sun light and water through the combination of photosystems and hydrogenases, and are suitable to cultivate in large scale.

In the present thesis the maturation process of [NiFe]-hydrogenases is investigated with special focus on transcription of the accessory genes encoding proteins needed for assembly of the large and possibly also for the small hydrogenase subunit. The cyanobacteria used are two N2-fixing, filamentous, heterocystous strains; Nostoc sp. strain PCC 7120 and Nostoc punctiforme PCC 73102.

For a biotechnological exploration of hydrogen production tools for regulatory purposes are important. The transcription factor CalA (cyanobacterial AbrB like) (Alr0946 in the genome) in Nostoc sp. strain PCC 7120 was found to be involved in hydrogen metabolism by regulating the transcription of the maturation protein HypC. Further the bidirectional hydrogenase activity was down-regulated in the presence of elevated levels of CalA, a result important to take into account when optimizing cyanobacteria for hydrogen production.

CalA regulates at least 25 proteins in Nostoc sp. strain PCC 7120 and one of the down-regulated proteins was superoxide dismutase, FeSOD. The characterization of FeSOD shows that it has a specific and important function in the oxidative stress tolerance of Nostoc sp. stain PCC 7120. Since CalA is involved in regulation of both the hydrogen metabolism as well as stress responses these findings indicate that Alr0946 is an important transcription factor in Nostoc sp. strain PCC 7120 active on a global level in the cell.

This thesis adds more knowledge concerning maturation and regulation of cyanobacterial hydrogenases which might be useful for future large scale hydrogen.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 62 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 695
Keyword
Biohydrogen, Cyanobacteria, Nostoc sp. PCC 7120, Nostoc punctiforme PCC 73102, Hydrogenase, Maturation, Transcriptional regulation, CyAbrB, CalA, FeSOD
Identifiers
urn:nbn:se:uu:diva-110871 (URN)978-91-554-7673-1 (ISBN)
Public defence
2010-01-15, Häggsalen, The Ångström Laboratory, Lägerhyddsvägen 1, Polacksbacken, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2009-12-21 Created: 2009-11-27 Last updated: 2009-12-21Bibliographically approved

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