Localization of putative carbonic anhydrases in two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana
Autor: | Yuri Endo, Masaaki Tachibana, Sae Kikutani, Yusuke Matsuda, Chris Bowler, Andrew E. Allen |
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Rok vydání: | 2011 |
Předmět: |
Chloroplasts
Recombinant Fusion Proteins Green Fluorescent Proteins Thalassiosira pseudonana Plant Science Biology Biochemistry Gene Expression Regulation Enzymologic Pyrenoid Transformation Genetic Carbonic anhydrase Seawater Amino Acid Sequence RNA Messenger Phaeodactylum tricornutum Cloning Molecular Gene Phylogeny Carbonic Anhydrases Diatoms Endoplasmic reticulum Cell Membrane Cell Biology General Medicine Periplasmic space Carbon Dioxide biology.organism_classification Mitochondria Chloroplast biology.protein Sequence Alignment |
Zdroj: | Photosynthesis Research. 109:205-221 |
ISSN: | 1573-5079 0166-8595 |
Popis: | It is believed that intracellular carbonic anhydrases (CAs) are essential components of carbon concentrating mechanisms in microalgae. In this study, putative CA-encoding genes were identified in the genome sequences of the marine diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana. Subsequently, the subcellular localizations of the encoded proteins were determined. Nine and thirteen CA sequences were found in the genomes of P. tricornutum and T. pseudonana, respectively. Two of the β-CA genes in P. tricornutum corresponded to ptca1 and ptca2 identified previously. Immunostaining transmission electron microscopy of a PtCA1:YFP fusion expressed in the cells of P. tricornutum clearly showed the localization of PtCA1 within the central part of the pyrenoid structure in the chloroplast. Besides these two β-CA genes, P. tricornutum likely contains five α- and two γ-CA genes, whereas T. pseudonana has three α-, five γ-, four δ-, and one ζ-CA genes. Semi-quantitative reverse transcription PCR performed on mRNA from the two diatoms grown in changing light and CO(2) conditions revealed that levels of six putative α- and γ-CA mRNAs in P. tricornutum did not change between cells grown in air-level CO(2) and 5% CO(2). However, mRNA levels of one putative α-CA gene, CA-VII in P. tricornutum, were reduced in the dark compared to that in the light. In T. pseudonana, mRNA accumulation levels of putative α-CA (CA-1), ζ-CA (CA-3) and δ-CA (CA-7) were analyzed and all levels found to be significantly reduced when cells were grown in 0.16% CO(2). Intercellular localizations of eight putative CAs were analyzed by expressing GFP fusion in P. tricornutum and T. pseudonana. In P. tricornutum, CA-I and II localized in the periplastidial compartment, CA-III, VI, VII were found in the chloroplast endoplasmic reticulum, and CA-VIII was localized in the mitochondria. On the other hand, T. pseudonana CA-1 localized in the stroma and CA-3 was found in the periplasm. These results suggest that CAs are constitutively present in the four chloroplastic membrane systems in P. tricornutum and that CO(2) responsive CAs occur in the pyrenoid of P. tricornutum, and in the stroma and periplasm of T. pseudonana. |
Databáze: | OpenAIRE |
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