title: Time-course global expression profiles of Chlamydomonas reinhardtii during photo-biological H₂ production.
abstract: We used a microarray study in order to compare the time course expression profiles of two Chlamydomonas reinhardtii strains, namely the high H₂ producing mutant stm6glc4 and its parental WT strain during H₂ production induced by sulfur starvation. Major cellular reorganizations in photosynthetic apparatus, sulfur and carbon metabolism upon H₂ production were confirmed as common to both strains. More importantly, our results pointed out factors which lead to the higher H₂ production in the mutant including a higher starch accumulation in the aerobic phase and a lower competition between the H₂ase pathway and alternative electron sinks within the H₂ production phase. Key candidate genes of interest with differential expression pattern include LHCSR3, essential for efficient energy quenching (qE). The reduced LHCSR3 protein expression in mutant stm6glc4 could be closely related to the high-light sensitive phenotype. H₂ measurements carried out with the LHCSR3 knock-out mutant npq4 however clearly demonstrated that a complete loss of this protein has almost no impact on H₂ yields under moderate light conditions. The nuclear gene disrupted in the high H₂ producing mutant stm6glc4 encodes for the mitochondrial transcription termination factor (mTERF) MOC1, whose expression strongly increases during -S-induced H₂ production in WT strains. Studies under phototrophic high-light conditions demonstrated that the presence of functional MOC1 is a prerequisite for proper LHCSR3 expression. Furthermore knock-down of MOC1 in a WT strain was shown to improve the total H₂ yield significantly suggesting that this strategy could be applied to further enhance H₂ production in other strains already displaying a high H₂ production capacity. By combining our array data with previously published metabolomics data we can now explain some of the phenotypic characteristics which lead to an elevated H₂ production in stm6glc4.
authors.affiliation: Department of Algae Biotechnology and Bioenergy, Faculty of Biology, Bielefeld University, Bielefeld, Germany.
authors.forename: Anh Vu
authors.initials: AV
authors.lastname: Nguyen
authors.forename: Joerg
authors.initials: J
authors.lastname: Toepel
authors.forename: Steven
authors.initials: S
authors.lastname: Burgess
authors.forename: Andreas
authors.initials: A
authors.lastname: Uhmeyer
authors.forename: Olga
authors.initials: O
authors.lastname: Blifernez
authors.forename: Anja
authors.initials: A
authors.lastname: Doebbe
authors.forename: Ben
authors.initials: B
authors.lastname: Hankamer
authors.forename: Peter
authors.initials: P
authors.lastname: Nixon
authors.forename: Lutz
authors.initials: L
authors.lastname: Wobbe
authors.forename: Olaf
authors.initials: O
authors.lastname: Kruse
mesh_terms: D000064:Acclimatization / Q000235:genetics / Q000528:radiation effects; D002452:Cell Count; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000235:genetics* / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D016000:Cluster Analysis; D030541:Databases, Genetic; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000528:radiation effects; D055785:Gene Knockdown Techniques; D017343:Genes, Plant / Q000235:genetics; D005816:Genetic Complementation Test; D006859:Hydrogen / Q000378:metabolism*; D008027:Light; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D052817:Phototrophic Processes / Q000235:genetics* / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011789:Quantum Theory; D013455:Sulfur / Q000172:deficiency; D013997:Time Factors; D059467:Transcriptome / Q000235:genetics / Q000528:radiation effects
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D002734:Chlorophyll; D013455:Sulfur; D006859:Hydrogen