Characterisation of the D1 protein in a photosystem II mutant (LF-1) of Scenedesmus obliquus blocked on the oxidising side Evidence supporting non-processing of D1 as the cause of the lesion

• Published in: FEBS letters 1988-08, Vol.235 (1), p.109-116
• Main Authors: Taylor, M.A., Nixon, P.J., Todd, C.M., Barber, J., Bowyer, J.R.
• Format: Article
• Language: English
• Subjects: azidoatrazine, 2-azido-4-ethylamino-6-isopropylamino-s-triazine; Biological and medical sciences; C-terminus, carboxyl-terminus of protein; Carboxyl-terminal processing; Cell structures and functions; Chloroplast, photosynthetic membrane and photosynthesis; D1 polypeptide; Fundamental and applied biological sciences. Psychology; LF-, low fluorescence; Molecular and cellular biology; Photosystem II; PS II, photosystem II; psbA gene product; Scenedesmus obliquus; SDS-PAGE, SDS-polyacrylamide gel electrophoresis
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(88)81243-2

The D1 polypeptide of the photosystem II reaction centre in a mutant (LF-1) of Scenedesmus obliquus lacking a water-splitting manganese complex is approx. 1.5 kDa larger than that in the wild type but the D2 protein is the same size. The peptide profiles of D1 on partial digestion with papain or endoproteinase Lys-C indicate that the extra segment in the LF-1 protein is located at or near the carboxyl-terminus. The D1 proteins produced by in vitro translation of mRNA from wild type and LF-1 cells have an identical molecular mass to D1 from LF-1 thylakoids whereas D1 from wild-type thylakoids is 1.5 kDa smaller due to C-terminal processing. These results support the hypothesis that in the LF-1 mutant, the D1 protein is incorporated into the PS II reaction centre, but the C-terminal extension is not removed.