Cloning and characterization of high-CO2-specific cDNAs from a marine microalga, Chlorococcum littorale, and effect of CO2 concentration and iron deficiency on the gene expression.
Two cDNA clones exclusively induced under an extremely high-CO2 concentration (20%) were isolated from Chlorococcum littorale by differential screening and named HCR (high-CO2 response) 1 and 2, respectively. The amino acid sequence of the protein encoded by HCR2 exhibited homology to the gp91-phox protein, a critical component of a human phagocyte oxidoreductase, and to the yeast ferric reductases, Saccharomyces cerevisiae FRE1 and FRE2 and Schizosaccharomyces pombe Frp1. The induction of both HCR mRNAs required extremely high-CO2 conditions and iron deficiency, being suppressed under air conditions and by iron sufficiency, suggesting that the expression of these two HCR genes required extremely high-CO2 conditions and iron deficiency in combination. The HCR2 protein was detected in the membrane fractions of cells grown under conditions which would favor the induction of HCR2-mRNA and the protein level was lowered when the cells were transferred from iron deficient to 10 microM FeSO4 conditions (with 20% CO2).
Sasaki
T
T
Marine Biotechnology Institute, Kamaishi Laboratories, Iwate, Japan.
Kurano
N
N
Miyachi
S
S
D020418:Algal Proteins; D000595:Amino Acid Sequence; D001483:Base Sequence; D002245:Carbon Dioxide / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D000460:Chlorophyta / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006801:Humans; D007501:Iron / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000737:chemistry; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D010088:Oxidoreductases / Q000737:chemistry; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D012568:Schizosaccharomyces / Q000201:enzymology; D012623:Seawater; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D020418:Algal Proteins; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D002245:Carbon Dioxide; D007501:Iron; D010088:Oxidoreductases; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases