title: Identification of a novel nifH-like (frxC) protein in chloroplasts of the liverwort Marchantia polymorpha.
abstract: The frxC gene, one of the unidentified open reading frames present in liverwort chloroplast DNA, shows significant homology with the nifH genes coding for the Fe protein, a component of the nitrogenase complex (Ohyama et al., 1986, Nature 322: 572-574). A truncated form of the frxC gene was designed to be over-expressed in Escherichia coli and an antibody against this protein was prepared using the purified product as an antigen. This antibody reacted with a protein in the soluble fraction of liverwort chloroplasts, which had an apparent molecular weight of 31,000, as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in good agreement with a putative molecular weight of 31,945 deduced from the DNA sequence of the frxC gene. In a competitive inhibition experiment, the antigenicity of this protein was indicated to be similar to that of the over-expressed protein in E. coli. Therefore, we concluded that the frxC gene was expressed in liverwort chloroplasts and that its product existed in a soluble form. The molecular weight of the frxC protein was approximately 67,000, as estimated by gel filtration chromatography, indicating that the frxC protein may exist as a dimer of two identical polypeptides analogous to the Fe protein of nitrogenase. The results obtained from affinity chromatography supported the possibility that the frxC protein, which possesses a ATP-binding sequence in its N-terminal region that is conserved among various other ATP-binding proteins, has the ability to bind ATP.
authors.affiliation: Department of Biology, Faculty of Science, Osaka University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Fujita
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Kohchi
authors.forename: H
authors.initials: H
authors.lastname: Ozeki
authors.forename: K
authors.initials: K
authors.lastname: Ohyama
authors.forename: H
authors.initials: H
authors.lastname: Matsubara
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002736:Chloroplasts / Q000378:metabolism; D004247:DNA / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009586:Nitrogen Fixation / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids
chemical_list: D010940:Plant Proteins; D000255:Adenosine Triphosphate; D004247:DNA