African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6578

Full Length Research Paper

Effects of ATP and Zn2+ on degradation of the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase in wheat leaves

Liefeng Zhang2, Ying Zhang1, Qi Rui1, Yong Ren2 and Langlai Xu1*
1Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, 210095 Nanjing, China. 2Jiangsu Key Laboratory for Supramolecular Medicinal and Applications, College of Life Sciences, Nanjing Normal University, Nanjing, China.
Email: [email protected]

  •  Published: 04 February 2010

Abstract

 Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) degradation is a complex process involving a multitude of proteolytic pathways, and its mechanism is still unclear now. We previously confirmed that a new senescence-associated protease in the stroma of chloroplasts from senescing leaves was suggested to be involved in the appearance of a 51 kDa fragment of Rubisco. In this study, the 51-kDa fragment was also detected when the crude extracts of mature leaves were incubated in Tris-HCl buffer (pH 7.5) with 1 mM ATP or the chloroplast lysates of mature leaves were incubated in the same buffer with 1 mM ATP and 1 μM Zn2+ for 1.5 h. However, the special degradation of large subunits (LSU) in the crude extracts of senescing leaves seemed to not to be affected by ATP and Zn2+ presence. Furthermore, the 51-kDa fragment could be detected when chloroplast lysates of senescing leaves were incubated in pH 7.5 Tris-HCl buffer containing 1 mM ATP and 1 μM Zn2+ only for 0.5 h, but it would be at least for 1 h if the buffer did not contain 1 mM ATP and 1 μM Zn2+. The results from this study implied that there would be two types of protease, which could specially degrade LSU into 51-kDa fragment, in cytoplasm or vacuole and in chloroplast of mature leaves respectively before leaf senescence.

 

Key words: ATP, Zn2+, Rubisco, protein degradation, wheat.