Identification of photosystem I components from the cyanobacterium, Synechococcus vulcanus by N-terminal sequencing.
The photosystem I core complex isolated from a thermophilic cyanobacterium, Synechococcus vulcanus, is composed of eight low-molecular-mass proteins of 18, 14, 12, 9.5, 9, 6.5, 5 and 4.1 kDa in addition to the PS I chlorophyll protein. N-terminal amino acid sequences of all these components were determined and compared with those of higher plants. Clearly, the 9.5 kDa component corresponds to the protein which carries the non-heme iron-sulfur centers A and B. This protein is so poorly visualized by staining that it has probably been overlooked in gel electrophoresis analyses. The 18, 14, 12 and 9 kDa components show appreciable homology with respective subunits of higher plant PS I. In contrast, the 6.5, 5 and 4.1 kDa components do not correspond to any known proteins except that the sequence of the 4.1 kDa component matches an unidentified open reading frame (ORF) 42 (liverwort) or ORF44 (tobacco) of chloroplast DNA.
Koike
H
H
Solar Energy Research Group, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Ikeuchi
M
M
Hiyama
T
T
Inoue
Y
Y
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002734:Chlorophyll / Q000032:analysis*; D000458:Cyanobacteria / Q000235:genetics / Q000502:physiology*; D005796:Genes; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins / Q000032:analysis; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D008970:Molecular Weight; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000032:analysis*
D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll