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Higher Plant Calreticulins Have Acquired Specialized Functions in Arabidopsis

Christensen, Anna LU ; Svensson, Karin LU ; Thelin, Lisa LU ; Zhang, WenJing LU ; Tintor, Nico; Prins, Daniel; Funke, Norma; Michalak, Marek; Schulze-Lefert, Paul and Saijo, Yusuke, et al. (2010) In PLoS ONE 5(6).
Abstract
Background: Calreticulin (CRT) is a ubiquitous ER protein involved in multiple cellular processes in animals, such as protein folding and calcium homeostasis. Like in animals, plants have evolved divergent CRTs, but their physiological functions are less understood. Arabidopsis contains three CRT proteins, where the two CRTs AtCRT1a and CRT1b represent one subgroup, and AtCRT3 a divergent member. Methodology/Principal Findings: Through expression of single Arabidopsis family members in CRT-deficient mouse fibroblasts we show that both subgroups have retained basic CRT functions, including ER Ca2+-holding potential and putative chaperone capabilities. However, other more general cellular defects due to the absence of CRT in the fibroblasts,... (More)
Background: Calreticulin (CRT) is a ubiquitous ER protein involved in multiple cellular processes in animals, such as protein folding and calcium homeostasis. Like in animals, plants have evolved divergent CRTs, but their physiological functions are less understood. Arabidopsis contains three CRT proteins, where the two CRTs AtCRT1a and CRT1b represent one subgroup, and AtCRT3 a divergent member. Methodology/Principal Findings: Through expression of single Arabidopsis family members in CRT-deficient mouse fibroblasts we show that both subgroups have retained basic CRT functions, including ER Ca2+-holding potential and putative chaperone capabilities. However, other more general cellular defects due to the absence of CRT in the fibroblasts, such as cell adhesion deficiencies, were not fully restored. Furthermore, in planta expression, protein localization and mutant analyses revealed that the three Arabidopsis CRTs have acquired specialized functions. The AtCRT1a and CRT1b family members appear to be components of a general ER chaperone network. In contrast, and as recently shown, AtCRT3 is associated with immune responses, and is essential for responsiveness to the bacterial Pathogen-Associated Molecular Pattern (PAMP) elf18, derived from elongation factor (EF)-Tu. Whereas constitutively expressed AtCRT1a fully complemented Atcrt1b mutants, AtCRT3 did not. Conclusions/Significance: We conclude that the physiological functions of the two CRT subgroups in Arabidopsis have diverged, resulting in a role for AtCRT3 in PAMP associated responses, and possibly more general chaperone functions for AtCRT1a and CRT1b. (Less)
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PLoS ONE
volume
5
issue
6
publisher
Public Library of Science
external identifiers
  • wos:000279259900015
  • scopus:77956223952
ISSN
1932-6203
DOI
10.1371/journal.pone.0011342
language
English
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yes
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bb76f680-f5b1-4602-83bc-4417483e92eb (old id 1628694)
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2010-07-21 16:47:14
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2018-06-24 04:25:33
@article{bb76f680-f5b1-4602-83bc-4417483e92eb,
  abstract     = {Background: Calreticulin (CRT) is a ubiquitous ER protein involved in multiple cellular processes in animals, such as protein folding and calcium homeostasis. Like in animals, plants have evolved divergent CRTs, but their physiological functions are less understood. Arabidopsis contains three CRT proteins, where the two CRTs AtCRT1a and CRT1b represent one subgroup, and AtCRT3 a divergent member. Methodology/Principal Findings: Through expression of single Arabidopsis family members in CRT-deficient mouse fibroblasts we show that both subgroups have retained basic CRT functions, including ER Ca2+-holding potential and putative chaperone capabilities. However, other more general cellular defects due to the absence of CRT in the fibroblasts, such as cell adhesion deficiencies, were not fully restored. Furthermore, in planta expression, protein localization and mutant analyses revealed that the three Arabidopsis CRTs have acquired specialized functions. The AtCRT1a and CRT1b family members appear to be components of a general ER chaperone network. In contrast, and as recently shown, AtCRT3 is associated with immune responses, and is essential for responsiveness to the bacterial Pathogen-Associated Molecular Pattern (PAMP) elf18, derived from elongation factor (EF)-Tu. Whereas constitutively expressed AtCRT1a fully complemented Atcrt1b mutants, AtCRT3 did not. Conclusions/Significance: We conclude that the physiological functions of the two CRT subgroups in Arabidopsis have diverged, resulting in a role for AtCRT3 in PAMP associated responses, and possibly more general chaperone functions for AtCRT1a and CRT1b.},
  author       = {Christensen, Anna and Svensson, Karin and Thelin, Lisa and Zhang, WenJing and Tintor, Nico and Prins, Daniel and Funke, Norma and Michalak, Marek and Schulze-Lefert, Paul and Saijo, Yusuke and Sommarin, Marianne and Widell, Susanne and Persson, Staffan},
  issn         = {1932-6203},
  language     = {eng},
  number       = {6},
  publisher    = {Public Library of Science},
  series       = {PLoS ONE},
  title        = {Higher Plant Calreticulins Have Acquired Specialized Functions in Arabidopsis},
  url          = {http://dx.doi.org/10.1371/journal.pone.0011342},
  volume       = {5},
  year         = {2010},
}