Cloning and nucleotide sequence of a frxC-ORF469 gene cluster of Synechocystis PCC6803: conservation with liverwort chloroplast frxC-ORF465 and nif operon.
A gene, frxC, which is unique to the chloroplast genome of the liverwort Marchantia polymorpha, has sequence similarity to nifH, the product of which is an iron protein of a nitrogenase. Although frxC is expressed to produce a protein in liverwort chloroplasts, its function is not known. Using a probe of liverwort chloroplast DNA, a 10.1-kb region containing a gene cluster consisting of open reading frames (ORF278-frxC-ORF469-ORF248) was isolated from the cyanobacterium Synechocystis PCC6803. In this region, frxC and ORF469 showed sequence similarities to liverwort chloroplast frxC (83%) and immediately downstream ORF465 (74%), respectively. Synechocystis frxC showed 31% amino acid sequence identity with nifH1 from Clostridium pasteurianum. Additionally, Synechocystis ORF469 showed a sequence similarity (19% identity) to C. pasteurianum nifK product, which is the beta subunit of a molybdenum-iron protein of a nitrogenase complex. Conservation of the gene arrangement between liverwort and Synechocystis suggests that the liverwort chloroplast frxC-ORF465 cluster may have evolved from an ancestor common to Synechocystis, and that these two genes may have been transferred to the nuclear genome in tobacco and rice during evolution.
Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan.
Y
Y
Ogura
M
M
Takemura
K
K
Oda
K
K
Yamato
E
E
Ohta
H
H
Fukuzawa
K
K
Ohyama
D000595:Amino Acid Sequence; D001483:Base Sequence; D002736:Chloroplasts / Q000502:physiology*; D003001:Cloning, Molecular; D003013:Clostridium / Q000235:genetics; D000458:Cyanobacteria / Q000235:genetics*; D016678:Genome; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics*; D009876:Operon / Q000235:genetics*; D010944:Plants / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid