Project leader

Peter Lindblad

Project members

Marie Holmqvist

Karin Stensjö

My PhD-work is a part of a larger project in the Cyanogroup, Department of Physiological Botany, where the hydrogen metabolism of cyanobacteria is being characterized. Our research aims to describe the direct, and indirect, regulation of enzymes that both produces and consumes hydrogen. The long-term goal is to produce biohydrogen using an engineered cyanobacterial strain. With biohydrogen we mean hydrogen produced from water with the expense of energy from sunlight. The hydrogen produced is then to be used as environmental friendly fuel since the only waste product is pure water. Achieving our goal would mean that we wouldn’t need coal, oil or nuclear power to sustain the world’s energy demand.

In cyanobacteria there are three main enzymes directly involved in hydrogen metabolism; the nitrogenase that produce molecular hydrogen as a by-product of nitrogen fixation, the uptake hydrogenase that consumes the hydrogen produced, thereby recapturing energy that would otherwise be lost from the bacteria, and the bidirectional hydrogenase that has the capacity to both produce and consume hydrogen [1]. The aim of my research is to study the genetical regulation of genes, coding for proteins that have, or may have importance for the synthesis and maturation of a functional hydrogenase. The organism I am working with is a filamentous cyanobacterium, Nostoc punctiforme ATCC 29133, originally found as a symbiont with the cycad Macrozamia.

One part of my work is the construction of a luciferase reporter gene system for studying transcriptional regulation. At present I’m studying transcriptional regulation of hupSL, whose g2009-06-09subunit of the uptake hydrogenase [2].

Another part is the study and characterization of an open reading frame, ORF, of unknown function. The gene product of this ORF we believe is involved in the hydrogen metabolism, since it is transcribed together with a set of genes, hyp-genes [3]. The gene products of the hyp-genes, Hyp proteins, are involved in the maturation of the functional uptake hydrogenase [4].

The third part of my research is to identify the function of a putative gene, hupC, presumably coding for the third subunit of the uptake hydrogenase. The gene product, HupC, is believed to anchor the HupS and HupL complex to the membrane and to function in electron transfer from the hydrogenase [5].

References

1. Tamagnini, P.,Axelsson, R., Lindberg, P., Oxelfelt, F., Wünschiers, R. and Lindblad, P., Hydrogenases and hydrogen metabolism of cyanobacteria. Microbiol. Mol. Biol. Rev., 2002. 66: 1-20.
2. Oxelfelt, F., Tamagnini, P. and Lindblad,P., Hydrogen uptake in Nostoc sp. strain PCC 73102. Cloning and characterization of a hupSL homologue. Arch. Microbiol., 1998. 169: 267-274.
3. Hansel, A., Axelsson, R., Lindberg, P., Troshina, O., Wünschiers, R. and Lindblad, P., Cloning and characterisation of a hyp gene cluster in the filamentous cyanobacterium Nostoc sp. strain PCC 73102. FEMS Microbiol. Lett., 2001. 201: 59-64.
4. Vignais, P.M., Billoud, B. And Meyer, J., Classification and phylogeny of hydrogenases. FEMS Microbiol. Rev, 2001. 25: 455-501.
5. Bernhard, M., Benelli, B., Hochkoeppler, A., Zannoni, D. and Friedrich, B., Functional and structural role of the cytochrome b subunit of the membrane-bound hydrogenase complex of Alcaligenes eutrophus H16. Eur. J. Biochem., 1997. 248: 179-186.

List of publications:

Posters

• Assembly of a functional cyanobacterialhydrogenase (PDF)
• Characterization of two putative hupC in Nostoc punctiforme 29133 (PDF)
• hyp-ORF1 and its Involvement in the Maturation Process of the Uptake Hydrogenase in Nostoc punctiforme ATCC 29133 (PDF)