Identification of bidirectional hydrogenase genes and their co-transcription in unicellular halotolerant cyanobacterium Aphanothece halophytica
- 277 Downloads
The halotolerant cyanobacterium Aphanothece halophytica has been shown to produce H2 via dark fermentation of accumulated glycogen under anoxic condition. One set of hox genes encoding a bidirectional hydrogenase is present in A. halophytica. In this study, the nucleotide sequence and the transcriptional analysis of hox genes in A. halophytica were investigated. The results revealed that A. halophytica contained five structural genes, hoxE, hoxF, hoxU, hoxY, and hoxH, without an insertion of other open reading frames (ORFs). The conserved cysteine motifs of iron-sulfur clusters involved in an electron transfer were found in all Hox subunits. The nucleotide and deduced amino acid sequences of hox genes in A. halophytica showed the highest identity and similarity to those of Halothece sp. PCC 7418. By reverse transcription polymerase chain reaction (RT-PCR) analysis, hox genes in A. halophytica were co-transcribed as a single operon. Under nitrogen-deprived condition, the transcripts of hoxH, glgB, coxA, ndhB, and psaA were upregulated whereas those of glgP and narB were downregulated which resulted in an increase of H2 production, H2ase activity, glycogen content, and dark respiration rate.
KeywordsHydrogenase gene Co-transcription Cyanobacteria Aphanothece halophytica
This study was financially supported by research grant from the Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang. A. Incharoensakdi thanks the Ratchadaphiseksomphot Endowment Fund of Chulalongkorn University, for the research grant under Frontier Research Energy Cluster.
- Appel J, Schulz R (1996) Sequence analysis of an operon of a NAD(P)-reducing nickel hydrogenase from the cyanobacterium Synechocystis sp. PCC 6803 gives additional evidence for direct coupling of the enzyme to NAD(P)-dehydrogenase (complex I). Biochim Biophys Acta 1298:141–147CrossRefPubMedGoogle Scholar
- Barz M, Beimgraben C, Staller T, Germer F, Opitz F, Marquardt C, Schwarz C, Gutekunst K, Vanselow KH, Schmitz R, LaRoche J, Schulz R, Appel J (2010) Distribution analysis of hydrogenases in surface waters of marine and freshwater environments. Plos One 5, e13846CrossRefPubMedPubMedCentralGoogle Scholar
- Higgins D, Thompson J, Gibson T, Thompson JD, Higgins DG, Gibson TJ (1994) CLUSTALW: Improving the sensitivity for progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Res 22:4673–4680CrossRefPubMedPubMedCentralGoogle Scholar
- Krasikov V, Wobeser EA, Yeremenko N, Ibelings BW, Huisman J, Matthijs HCM (2010) Gene expression of the cyanobacterium Synechocystis PCC 6803 in response to nitrogen starvation. In: Wobeser EA (ed) Genome-wide expression analysis of environmental stress in the cyanobacterium Synechocystis PCC 6803. UvA-DARE, Amsterdam, pp 55–74Google Scholar
- MacKinney G (1941) Absorption of light by chlorophyll solutions. J Biol Chem 140:315–322Google Scholar
- Schmitz O, Bothe H (1996) Thediaphorase subunit HoxU of the bidirectional hydrogenase as electron transferring protein in cyanobacterial respiration? Naturwissenschaften 83:525–527Google Scholar
- Zhang X, Shiraiwa Y, Sui ZH, Zhang XC (2005a) Cloning and characterization of hoxY gene from Arthrospira and Spirulina and its application in phylogenetic studies. Periodical Ocean Univ China 35:1021–1025Google Scholar