IDENTIFICATION AND DNA SEQUENCE OF A NEW H⁺‐ATPase IN THE UNICELLULAR GREEN ALGA CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE)

Abstract

Insertional mutagenesis was used to identify genes involved in mating and/or zygote formation in the unicellular green alga Chlamydomonas reinhardtii Dangeard. Approximately 800 insertionally mutagenized transformants were examined, and a single nonagglutinating mutant was identified. Plasmid rescue was used to clone a genomic fragment containing transforming DNA. This fragment was then used to identify the wild-type copy of the gene disrupted during mutagenesis. The wild-type gene is transcribed during all stages of the life cycle and, based on sequence similarity, encodes a P2-type proton transporting ATPase. The gene is referred to as Pmh1 for plasma membrane H ϩ -ATPase. PMH1 displays the greatest sequence similarity to ATPases from two parasitic flagellates and a raphidophytic alga but not to the ATPase from a closely related green alga. We propose that PMH1 represents a distinct H ϩ -ATPase isoform expressed in flagellates.

Evolution of Plant P-Type ATPases

“…In Chlamydomonas , two plasma membrane H + -ATPases have been described in the literature (Campbell et al, 2001 ). Closely related homologs to OtAHA2 are found in other green algae but not in streptophytes.…”

Plasma Membrane Domains Participate in pH Banding of Chara Internodal Cells

“…Our data support the hypothesis that charasomes are involved in active medium acidification caused by the activity of a H + -ATPase ( Franceschi and Lucas, 1982 , Price and Whitecross 1983 ). In this study we used an antibody raised against a synthetic peptide derived from various higher plant and algal plasma membrane ATPase sequences including those of Arabidopsis thaliana ( Harper et al 1989 ) and Chlamydomonas reinhardtii ( Campbell et al 2001 ). The antibody showed a strong and highly specific cross-reaction in the appropriate 100 kDa range in Western blot analysis, and immunolocalization revealed an accumulation of proton pumps within charasomes, confirming the idea of active acidification mediated through charasome-associated H + -ATPase activity in acid bands.…”

Energizing the plasmalemma of marine photosynthetic organisms: the role of primary active transport

“…Further investigation is needed into the possibility of direct redox energization of Na + efflux from Dunaliella salina (Katz & Pick, 2001). The freshwater Chlamydomonas reinhardtii has a P-type Na + -ATPase (Barrero-Gil et al ., 2005; Rodríguez-Navarro & Benito, 2010), as well as a P-type H + -ATPase (Campbell et al ., 2001; Barrero-Gil et al ., 2005; Bertucci et al ., 2010).…”