Abstract |
Modulation of cytosolic calcium levels in both plants and animals is achieved by a system of Ca2+-transport and storage pathways that include Ca2+ buffering proteins in the lumen of intracellular compartments. To date, most research has focused on the role of transporters in regulating cytosolic calcium. We used a reverse genetics approach to modulate calcium stores in the lumen of the endoplasmic reticulum. Our goals were two-fold: to use the low affinity, high capacity Ca2+ binding characteristics of the C-domain of calreticulin to selectively increase Ca2+ storage in the endoplasmic reticulum, and to determine if those alterations affected plant physiological responses to stress. The C-domain of calreticulin is a highly acidic region that binds 20-50 moles of Ca2+ per mole of protein and has been shown to be the major site of Ca2+ storage within the endoplasmic reticulum of plant cells. A 377-bp fragment encoding the C-domain and ER retention signal from the maize calreticulin gene was fused to a gene for the green fluorescent protein and expressed in Arabidopsis under the control of a heat shock promoter. Following induction on normal medium, the C-domain transformants showed delayed loss of chlorophyll after transfer to calcium depleted medium when compared to seedlings transformed with green fluorescent protein alone. Total calcium measurements showed a 9-35% increase for induced C-domain transformants compared to controls. The data suggest that ectopic expression of the calreticulin C-domain increases Ca2+ stores, and that this Ca2+ reserve can be used by the plant in times of stress.
|
Authors | Sarah E Wyatt, Pei-Lan Tsou, Dominique Robertson |
Journal | Transgenic research
(Transgenic Res)
Vol. 11
Issue 1
Pg. 1-10
(Feb 2002)
ISSN: 0962-8819 [Print] Netherlands |
PMID | 11874098
(Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
|
Chemical References |
- Calcium-Binding Proteins
- Calreticulin
- Luminescent Proteins
- Ribonucleoproteins
- Green Fluorescent Proteins
- Calcium
|
Topics |
- Agrobacterium tumefaciens
(genetics)
- Arabidopsis
(genetics, growth & development)
- Biological Availability
- Calcium
(metabolism)
- Calcium-Binding Proteins
(chemistry, metabolism)
- Calreticulin
- Genetic Vectors
- Green Fluorescent Proteins
- Luminescent Proteins
(genetics)
- Phenotype
- Plants, Genetically Modified
- Ribonucleoproteins
(chemistry, metabolism)
- Zea mays
(genetics, metabolism)
|