The degradation of the large subunit of ribulose-1,5-bisphosphate carboxylase [RUBISCO]/oxygenase into the 44-kDa fragment in the lysates of chloroplasts incubated in darkness

• Published in: Plant and cell physiology 2002-11, Vol.43 (11), p.1390-1395
• Main Authors: Kokubun, N. (Tohoku Univ., Sendai (Japan)), Ishida, H, Makino, A, Mae, T
• Format: Article
• Language: English
• Subjects: 5-bisphosphate carboxylase/oxygenase; 5-bisphosphate carboxylase/oxygenase (Rubisco; anti-LSU-N or anti-LSU-C; Chloroplast — Protease — Protein degradation — Ribulose-1; CHLOROPLASTS; Chloroplasts - enzymology; Chloroplasts - radiation effects; DARKNESS; DEGRADATION; EC 4.1.1.39) — Wheat (Triticum aestivum; Endopeptidases - metabolism; large subunit of ribulose-1; LSU; Plant Leaves - enzymology; Protein Conformation; ribulose-1; Ribulose-Bisphosphate Carboxylase - chemistry; Ribulose-Bisphosphate Carboxylase - metabolism; RUBISCO; site-specific antibodies against N-terminal or C-terminal portion of the large subunit of ribulose-1; Triticum - enzymology; TRITICUM AESTIVUM
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcf159

Lysates of chloroplasts isolated from naturally senescing wheat leaves were incubated in darkness. The 44-kDa fragment, lacking the N-terminal-side portion of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (LSU), was found by immunoblotting with the LSU site-specific antibodies. Analysis of its N-terminal amino acid sequence indicated that the LSU was specifically cleaved at the peptide bond between Phe-40 and Arg-41. The site was located on the surface of the molecule and faced outward. Such cleavage of the LSU has not been previously reported. It is indicated that the cleavage was triggered by an unknown protease existing in chloroplasts.