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The chloroplast-localized small heat shock protein Hsp21 associates with the thylakoid membranes in heat-stressed plants

Bernfur, Katja LU ; Rutsdottir, Gudrun LU and Emanuelsson, Cecilia LU (2017) In Protein Science 26(9). p.1773-1784
Abstract

The small heat shock protein (sHsp) chaperones are crucial for cell survival and can prevent aggregation of client proteins that partially unfold under destabilizing conditions. Most investigations on the chaperone activity of sHsps are based on a limited set of thermosensitive model substrate client proteins since the endogenous targets are often not known. There is a high diversity among sHsps with a single conserved β-sandwich fold domain defining the family, the α-crystallin domain, whereas the N-terminal and C-terminal regions are highly variable in length and sequence among various sHsps and conserved only within orthologues. The endogenous targets are probably also varying among various sHsps, cellular compartments, cell type and... (More)

The small heat shock protein (sHsp) chaperones are crucial for cell survival and can prevent aggregation of client proteins that partially unfold under destabilizing conditions. Most investigations on the chaperone activity of sHsps are based on a limited set of thermosensitive model substrate client proteins since the endogenous targets are often not known. There is a high diversity among sHsps with a single conserved β-sandwich fold domain defining the family, the α-crystallin domain, whereas the N-terminal and C-terminal regions are highly variable in length and sequence among various sHsps and conserved only within orthologues. The endogenous targets are probably also varying among various sHsps, cellular compartments, cell type and organism. Here we have investigated Hsp21, a non-metazoan sHsp expressed in the chloroplasts in green plants which experience huge environmental fluctuations not least in temperature. We describe how Hsp21 can also interact with the chloroplast thylakoid membranes, both when isolated thylakoid membranes are incubated with Hsp21 protein and when plants are heat-stressed. The amount of Hsp21 associated with the thylakoid membranes was precisely determined by quantitative mass spectrometry after metabolic 15N-isotope labeling of either recombinantly expressed and purified Hsp21 protein or intact Arabidopsis thaliana plants. We found that Hsp21 is among few proteins that become associated with the thylakoid membranes in heat-stressed plants, and that approximately two thirds of the pool of chloroplast Hsp21 is affected. We conclude that for a complete picture of the role of sHsps in plant stress resistance also their association with the membranes should be considered.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Chaperone, Heat shock protein, Membranes, Photosynthesis, Quantitative mass spectrometry, Stable isotope labeling, Stress response, Thermomemory
in
Protein Science
volume
26
issue
9
pages
1773 - 1784
publisher
The Protein Society
external identifiers
  • scopus:85021371930
  • wos:000409861900009
ISSN
0961-8368
DOI
10.1002/pro.3213
language
English
LU publication?
yes
id
c39ed0c6-71b3-44bd-ae7d-1c63648fa85e
date added to LUP
2017-07-12 14:41:50
date last changed
2018-04-08 04:58:46
@article{c39ed0c6-71b3-44bd-ae7d-1c63648fa85e,
  abstract     = {<p>The small heat shock protein (sHsp) chaperones are crucial for cell survival and can prevent aggregation of client proteins that partially unfold under destabilizing conditions. Most investigations on the chaperone activity of sHsps are based on a limited set of thermosensitive model substrate client proteins since the endogenous targets are often not known. There is a high diversity among sHsps with a single conserved β-sandwich fold domain defining the family, the α-crystallin domain, whereas the N-terminal and C-terminal regions are highly variable in length and sequence among various sHsps and conserved only within orthologues. The endogenous targets are probably also varying among various sHsps, cellular compartments, cell type and organism. Here we have investigated Hsp21, a non-metazoan sHsp expressed in the chloroplasts in green plants which experience huge environmental fluctuations not least in temperature. We describe how Hsp21 can also interact with the chloroplast thylakoid membranes, both when isolated thylakoid membranes are incubated with Hsp21 protein and when plants are heat-stressed. The amount of Hsp21 associated with the thylakoid membranes was precisely determined by quantitative mass spectrometry after metabolic <sup>15</sup>N-isotope labeling of either recombinantly expressed and purified Hsp21 protein or intact Arabidopsis thaliana plants. We found that Hsp21 is among few proteins that become associated with the thylakoid membranes in heat-stressed plants, and that approximately two thirds of the pool of chloroplast Hsp21 is affected. We conclude that for a complete picture of the role of sHsps in plant stress resistance also their association with the membranes should be considered.</p>},
  author       = {Bernfur, Katja and Rutsdottir, Gudrun and Emanuelsson, Cecilia},
  issn         = {0961-8368},
  keyword      = {Chaperone,Heat shock protein,Membranes,Photosynthesis,Quantitative mass spectrometry,Stable isotope labeling,Stress response,Thermomemory},
  language     = {eng},
  number       = {9},
  pages        = {1773--1784},
  publisher    = {The Protein Society},
  series       = {Protein Science},
  title        = {The chloroplast-localized small heat shock protein Hsp21 associates with the thylakoid membranes in heat-stressed plants},
  url          = {http://dx.doi.org/10.1002/pro.3213},
  volume       = {26},
  year         = {2017},
}