title: Cloning and overexpression of two cDNAs encoding the low-CO2-inducible chloroplast envelope protein LIP-36 from Chlamydomonas reinhardtii.
abstract: Chlamydomonas reinhardtii, a unicellular green alga, grows photoautotrophically at very low concentrations of inorganic carbon due to the presence of an inducible CO2-concentrating mechanism. During the induction of the CO2-concentrating mechanism at low-CO2 growth conditions, at least five polypeptides that are either absent or present in low amounts in cells grown on high-CO2 concentrations are induced. One of these induced polypeptides with a molecular mass of 36 kD, LIP-36, has been localized to the chloroplast envelope. The protein was purified and the partial internal amino acid sequences were obtained through lys-C digestion. Two cDNAs encoding LIP-36 have been cloned using degenerate primers based on the amino acid sequences. The two genes encoding LIP-36 are highly homologous in the coding region but are completely different in the 5'-end and 3'-end untranslated regions. The deduced protein sequences show strong homology to the mitochondrial carrier protein superfamily, suggesting that LIP-36 is a chloroplast carrier protein. The regulation of the expression of these two genes at high- and low-CO2 growth conditions is also different. Both genes were highly expressed under low-CO2 growth conditions, with the steady-state level of LIP-36 G1 mRNA more abundant. However, neither gene was expressed at high-CO2 growth conditions. The gene products of both clones expressed in Escherichia coli were recognized by an antibody raised against LIP-36, confirming that the two cDNAs indeed encode the C. reinhardtii chloroplast envelope carrier protein LIP-36.
authors.affiliation: Department of Plant Biology, Louisiana State University, Baton Rouge 70803, USA.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Chen
authors.forename: L L
authors.initials: LL
authors.lastname: Lavigne
authors.forename: C B
authors.initials: CB
authors.lastname: Mason
authors.forename: J V
authors.initials: JV
authors.lastname: Moroney
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002245:Carbon Dioxide / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D060365:Chloroplast Proteins; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D016054:DNA, Protozoan / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D060365:Chloroplast Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D002245:Carbon Dioxide