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Abstract Detail


Protein Modification and Turnover

Shen, Guoxin [1], Adam, Zach [2], Zhang, Hong [3].

The E3 ligase AtCHIP ubiquitylates FtsH1, a component of the chloroplast FtsH protease, and regulates protein degradation in chloroplasts.

The Arabidopsis protein, AtCHIP, is an E3 ubiquitin ligase that plays important roles in plant response to environmental stress conditions. AtCHIP interacts with several proteins, including FtsH1, a subunit of the chloroplast FtsH protease complex in plant cells. FtsH is an ATP-dependent metalloprotease that is thought to degrade misfolded, unassembled or damaged proteins in thylakoid membranes, as well as some proteins in chloroplast stroma. We found that FtsH1 can be ubiquitylated by AtCHIP in vitro, and the steady-state level of FtsH1 is reduced in AtCHIP-overexpressing plants under high-intensity light condition, suggesting that the ubiquitylation of FtsH1 by AtCHIP may lead to FtsH1ís degradation in vivo. One substrate of FtsH protease in vivo, the photosystem II reaction center protein D1, is not efficiently removed by FtsH in AtCHIP-overexpressing plants under high-intensity light condition, supporting the assumption that FtsH1 is a substrate of AtCHIP in vivo and AtCHIP-overexpression may lead to reduced level of FtsH in chloroplasts. AtCHIP-overexpressing plants display localized cell death phenotype under high-intensity light condition, which is a typical symptom of reduced FtsH level in chloroplast. A similar cell death phenotype can be observed in FtsH1-antisense plants, which adds further support that there is a causal relationship between increased expression of AtCHIP and decreased FtsH activity in chloroplast. Therefore, AtCHIP plays an important role in protein quality control in chloroplast in addition to its other important roles in plant cellular metabolisms.


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1 - Texas Tech University, Biological Sciences
2 - The Hebrew University of Jerusalem, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture
3 - Texas Tech University, Department of Biological Sciences, Lubbock, TX, 79409, USA

Keywords:
AtCHIP E3 ligase
chloroplast proteases
protein degradation
protein quality control
ubiquitylation.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P37002
Abstract ID:61


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