OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 144/1/513    most recent pp.106.094581v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Nakayama, K. Articles by Inaba, T. Search for Related Content PubMed PubMed Citation Articles by Nakayama, K. Articles by Inaba, T. Agricola Articles by Nakayama, K. Articles by Inaba, T.

ENVIRONMENTAL STRESS AND ADAPTATION TO STRESS

Arabidopsis Cor15am Is a Chloroplast Stromal Protein That Has Cryoprotective Activity and Forms Oligomers^1,[W],[OA]

The 21st Century Centers of Excellence Program, Cryobiosystem Research Center, Iwate University, Morioka 020–8550, Japan (K.N., K.O., T.K., T.I.); and Department of Material-Process Engineering and Applied Chemistry for Environment, Faculty of Engineering and Resource Science, Akita University, Akita 010–8502, Japan (T.H., H.I.)

Many plants acquire increased freezing tolerance when they are exposed to nonfreezing temperatures of a certain duration. This process is known as cold acclimation and allows plants to protect themselves from freezing injury. A wide variety of polypeptides are induced during cold acclimation, among which is one encoded by COR15A in Arabidopsis (Arabidopsis thaliana). Previous studies showed that the COR15A gene encodes a small, plastid-targeted polypeptide that is processed to a mature form called Cor15am. In this study, we examined the biochemical properties and activities of Cor15am in more detail. We provide evidence that Cor15am localizes almost exclusively to the chloroplast stroma. In addition, the cold-regulated accumulation of Cor15am is affected by chloroplast functionality. Both gel-filtration chromatography and protein cross-linking reveal that Cor15am forms oligomers in the stroma of chloroplasts. Although Cor15am accumulates in response to low temperature, cold acclimation is not a prerequisite for oligomerization of Cor15am. Structural analysis suggests that Cor15am is composed of both ordered and random structures, and can stay soluble with small structural change after boiling and freeze-thaw treatments. Recombinant Cor15am exhibits in vitro cryoprotection of a freeze-labile enzyme, L-lactate dehydrogenase. Furthermore, Cor15am is capable of associating with L-lactate dehydrogenase in vitro and with potential stromal substrates in vivo. On the basis of these results, we propose that Arabidopsis Cor15am is a cryoprotective protein that forms oligomers in the chloroplast stroma, and that direct association of Cor15am with its substrates is part of its cryoprotective mechanism.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Takehito Inaba (tinaba{at}iwate-u.ac.jp).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.106.094581

^* Corresponding author; e-mail tinaba{at}iwate-u.ac.jp; fax 81–19–621–6200.

Received December 11, 2006; accepted March 20, 2007; published March 23, 2007.

This article has been cited by other articles:

				T. Kakizaki, H. Matsumura, K. Nakayama, F.-S. Che, R. Terauchi, and T. Inaba Coordination of Plastid Protein Import and Nuclear Gene Expression by Plastid-to-Nucleus Retrograde Signaling Plant Physiology, November 1, 2009; 151(3): 1339 - 1353. [Abstract] [Full Text] [PDF]

				M. T. Waters, P. Wang, M. Korkaric, R. G. Capper, N. J. Saunders, and J. A. Langdale GLK Transcription Factors Coordinate Expression of the Photosynthetic Apparatus in Arabidopsis PLANT CELL, April 1, 2009; 21(4): 1109 - 1128. [Abstract] [Full Text] [PDF]

				Y. Ito-Inaba, Y. Hida, H. Mori, and T. Inaba Molecular Identity of Uncoupling Proteins in Thermogenic Skunk Cabbage Plant Cell Physiol., December 1, 2008; 49(12): 1911 - 1916. [Abstract] [Full Text] [PDF]

				M. Battaglia, Y. Olvera-Carrillo, A. Garciarrubio, F. Campos, and A. A. Covarrubias The Enigmatic LEA Proteins and Other Hydrophilins Plant Physiology, September 1, 2008; 148(1): 6 - 24. [Full Text] [PDF]