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Abstract Detail


Temperature Responses

Okawa, Kumiko [1], Nakayama, Katsuhiro [1], Kakizaki, Tomohiro [2], Yamashita, Tetsuro [3], Inaba, Takehito [4].

Identification and characterization of Cor413im proteins as novel inner envelope membrane proteins of chloroplasts implicated in cold acclimation.

Chloroplasts are essential organelles in plant cells and have numerous metabolic activities, including photosynthesis. The organelle is surrounded by envelope membranes that allow compartmentalization of chloroplasts from the cytosol. When plants are exposed to abiotic stresses, such as low temperature, the envelope structure is often damaged. While plants are known to accumulate stromal proteins during cold acclimation (e.g., Nakayama et al., (2007) Plant Physiol., accepted), envelope membrane proteins involved in low-temperature or freezing tolerance have not been identified yet. We identified novel inner envelope membrane proteins, designated as Cor413im, implicated in cold acclimation of Arabidopsis thaliana. As a first step of our analysis, we generated Arabidopsis constitutively expressing protein-A fusion construct. Biochemical analyses demonstrated that Cor413im was an integral membrane protein at the inner envelope of chloroplasts and was processed to the mature form during import into chloroplasts. Determination of the N-terminal sequence revealed that the protein largely consisted of transmembrane domains. In addition, gel-filtration and immunoaffinity chromatographies suggested that Cor413im formed the high molecular weight complexes but did not stably associate with other inner envelope proteins examined. To address the function of Cor413im in vivo, we isolated T-DNA knockout lines. Electrolyte leakage assay revealed that the disruption of COR413IM genes impaired freezing tolerance. Based on these data, we propose that Cor413im proteins are inner envelope membrane proteins of chloroplasts implicated in cold acclimation. We will also discuss possible mechanisms by which Cor413im proteins protect chloroplasts from freeze-induced damages.


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Inaba Lab


1 - Iwate University, The 21st Century COE program
2 - Iwate University, Cryobiosystem Research Center
3 - Iwate University, Faculty of Agriculture
4 - Iwate University, The 21st Century COE program, Cryobiosystem Research Center, Iwate University, 3-18-8 Ueda, Morioka, 0208550, Japan

Keywords:
chloroplast envelope
Cor413im
freezing tolerance
membrane protein.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P08006
Abstract ID:193


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