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Expression activation and functional analysis of HLA 3, a putative inorganic carbon transporter in C hlamydomonas reinhardtii
Author(s) -
Gao Han,
Wang Yingjun,
Fei Xiaowen,
Wright David A.,
Spalding Martin H.
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12788
Subject(s) - chlamydomonas reinhardtii , rubisco , carbonic anhydrase , photosynthesis , effector , chlamydomonas , total inorganic carbon , microbiology and biotechnology , biochemistry , assimilation (phonology) , chemistry , gene expression , biology , biophysics , mutant , gene , carbon dioxide , enzyme , ecology , linguistics , philosophy
Summary The CO 2 concentrating mechanism (CCM) is a key component of the carbon assimilation strategy of aquatic microalgae. Induced by limiting CO 2 and tightly regulated, the CCM enables these microalgae to respond rapidly to varying environmental CO 2 supplies and to perform photosynthetic CO 2 assimilation in a cost‐effective way. A functional CCM in eukaryotic algae requires Rubisco sequestration, rapid interconversion between CO 2 and HCO 3 − catalyzed by carbonic anhydrases (CAs), and active inorganic carbon (Ci) uptake. In the model microalga Chlamydomonas reinhardtii , a membrane protein HLA3 is proposed to be involved in active Ci uptake across the plasma membrane. In this study, we use an artificially designed transcription activator‐like effector ( dTALE ) to activate the expression of HLA3. The successful activation of HLA3 expression demonstrates dTALE as a promising tool for gene‐specific activation and investigation of gene function in Chlamydomonas . Activation of HLA3 expression in high CO 2 acclimated cells, where HLA3 is not expressed, resulted in increased Ci accumulation and Ci‐dependent photosynthetic O 2 evolution specifically in very low CO 2 concentrations, which confirms that HLA3 is indeed involved in Ci uptake, and suggests it is mainly associated with HCO 3 − transport in very low CO 2 concentrations, conditions in which active CO 2 uptake is highly limited.