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An AbrB-Like Protein Regulates the Expression of the Bidirectional Hydrogenase in Synechocystis sp. Strain PCC 6803.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
2008 (English)In: Journal of Bacteriology, ISSN 0021-9193, Vol. 190, no 3, 1011-1019 p.Article in journal (Refereed) Published
Abstract [en]

In the unicellular cyanobacterium Synechoeystis sp. strain PCC 6803, the pentameric bidirectional Ni-Fe hydrogenase (HoxEFUYH) is the sole enzyme involved in hydrogen metabolism. Recent investigations implicated the transcription factor LexA in the regulation of the hox genes in this cyanobacterium, suggesting the factor to work as an activator. In this work, we show evidence that LexA cannot account exclusively for the regulation of the hox genes in this cyanobacterium. Therefore, we investigated which additional transcription factors interact in and may regulate the expression of the hox genes in Synechocystis sp. strain PCC 6803. By using DNA affinity assays, a transcription factor with similarity to the transition state regulator AbrB from Bacillus subtilis was isolated. Electrophoretic mobility shift assays showed that the AbrB-like protein specifically interacts with the promoter region of the hox genes as well as with its own promoter region. In addition, results obtained with two genetically modified strains of Synechoeystis sp. strain PCC 6803, one with a not fully segregated inactivation mutation of the abrB-like gene and the other overexpressing the same abrB-like gene, suggest that this transcription factor functions as a regulator of hox gene expression.

Place, publisher, year, edition, pages
2008. Vol. 190, no 3, 1011-1019 p.
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-97278DOI: 10.1128/JB.01605-07ISI: 000252616800026OAI: oai:DiVA.org:uu-97278DiVA: diva2:172142
Available from: 2008-05-14 Created: 2008-05-14 Last updated: 2012-08-22
In thesis
1. Regulation of the Cyanobacterial Bidirectional Hydrogenase
Open this publication in new window or tab >>Regulation of the Cyanobacterial Bidirectional Hydrogenase
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Today, mankind faces a new challenge in energetic terms: a new Industrial Revolution is imperative, already called by some as an Energetic Revolution. This corresponds to a conversion to clean, environmentally friendly and renewable energy sources. In this context, hydrogen arises as a valid alternative, since its combustion produces a considerable amount of energy and releases solely water as a by-product. In the present thesis, two model cyanobacteria, namely Synechocystis sp. strain PCC 6803 and Anabaena/Nostoc sp. strain PCC 7120, were used to examine the hydrogen metabolism. The efforts were focused on to understand the transcription regulation of the hox genes, encoding the structural elements of the bidirectional hydrogenase enzyme. Here, it is shown that such regulation is operated in a very distinct and intricate way, with different factors contributing to its delicate tuning. While in Synechocystis sp. strain PCC 6803 the hox genes were shown to be transcribed as a single operon, in Anabaena/Nostoc sp. strain PCC 7120 they were shown to be transcribed as two independent operons (possibly three). Two transcription factors, LexA and AbrB-like protein, were identified and further characterized in relation to the hydrogen metabolism. Furthermore, different environmental conditions were demonstrated to operate changes on the transcription of the bidirectional hydrogenase genes. In addition, functional studies of three open reading frames found within the hox operon of Synechocystis sp. strain PCC 6803 suggest that this may be a stress responsive operon. However, based on the gained knowledge, it is still not possible to connect the signal transduction pathways, from the environmental signal, through the response regulator, to the final regulation of the hox genes. Nevertheless, the crucial importance of studying the transcription regulation of the different players involved in the hydrogen metabolism is now established and a new era seems to be rising.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 63 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 437
Keyword
Biology, Biohydrogen, Cyanobacteria, Synechocystis, Anabaena/Nostoc, Bidirectional hydrogenase, Transcription regulation, LexA, AbrB-like protein, Biologi
Identifiers
urn:nbn:se:uu:diva-8862 (URN)978-91-554-7215-3 (ISBN)
Public defence
2008-06-05, Å2001, The Ångström Laboratory, Lägerhyddsvägen 1, Polacksbacken,, Uppsala, 10:15 (English)
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Available from: 2008-05-14 Created: 2008-05-14 Last updated: 2009-08-17Bibliographically approved

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Lindblad, Peter

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