Photosynthesis Research

, Volume 109, Issue 1, pp 205–221

Localization of putative carbonic anhydrases in two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana

Authors

  • Masaaki Tachibana
    • Department of Bioscience, School of Science and TechnologyKwansei Gakuin University
  • Andrew E. Allen
    • Environmental and Evolutionary Genomics Section, Institut de Biologie de l’Ecole Normale Supérieure (IBENS)CNRS UMR8197 INSERM U1024, Ecole Normale Supérieure
    • J. Craig Venter Institute
  • Sae Kikutani
    • Department of Bioscience, School of Science and TechnologyKwansei Gakuin University
  • Yuri Endo
    • Department of Bioscience, School of Science and TechnologyKwansei Gakuin University
  • Chris Bowler
    • Environmental and Evolutionary Genomics Section, Institut de Biologie de l’Ecole Normale Supérieure (IBENS)CNRS UMR8197 INSERM U1024, Ecole Normale Supérieure
    • Department of Bioscience, School of Science and TechnologyKwansei Gakuin University
Regular Paper

DOI: 10.1007/s11120-011-9634-4

Cite this article as:
Tachibana, M., Allen, A.E., Kikutani, S. et al. Photosynth Res (2011) 109: 205. doi:10.1007/s11120-011-9634-4

Abstract

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 CO2 conditions revealed that levels of six putative α- and γ-CA mRNAs in P. tricornutum did not change between cells grown in air-level CO2 and 5% CO2. 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% CO2. 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 CO2 responsive CAs occur in the pyrenoid of P. tricornutum, and in the stroma and periplasm of T. pseudonana.

Keywords

Marine diatomCarbonic anhydraseInorganic carbon concentrating mechanismPyrenoid

Abbreviations

Rubisco

Ribulose-1,5-bisphosphate carboxylase/oxygenase

CA

Carbonic anhydrase

CER

Chloroplast endoplasmic reticulum

PPC

Periplastidial compartment

BLS

Blob-like structure

CE

Chloroplast envelope

CCM

Inorganic carbon concentrating mechanism

TEM

Transmission electron microscopy

Supplementary material

11120_2011_9634_MOESM1_ESM.eps (978 kb)
Supplementary material 1 (EPS 978 kb)
11120_2011_9634_MOESM2_ESM.doc (60 kb)
Supplementary material 2 (DOC 59 kb)
11120_2011_9634_MOESM3_ESM.doc (62 kb)
Supplementary material 3 (DOC 62 kb)
11120_2011_9634_MOESM4_ESM.doc (40 kb)
Supplementary material 4 (DOC 39 kb)
11120_2011_9634_MOESM5_ESM.doc (45 kb)
Supplementary material 5 (DOC 45 kb)

Copyright information

© Springer Science+Business Media B.V. 2011