The function of small heat-shock proteins and their implication in proteostasis

2016 ◽  
Vol 60 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Annika Strauch ◽  
Martin Haslbeck
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Small Heat Shock Proteins ◽  
Independent Manner ◽  
Native Proteins ◽  
Domains Of Life ◽  
Broad Variety ◽  
Chaperone Network ◽  
Shock Proteins

All organisms rely on a conserved cellular machinery supporting and controlling the life cycle of proteins: the proteostasis network. Within this network, the main players that determine the fate of proteins are molecular chaperones, the ubiquitin–proteasome and the lysosome–autophagy systems. sHsps (small heat-shock proteins) represent one family of molecular chaperones found in all domains of life. They prevent irreversible aggregation of unfolded proteins and maintain proteostasis by stabilizing promiscuously a variety of non-native proteins in an ATP-independent manner. In the cellular chaperone network, sHsps act as the first line of defence and keep their substrates in a folding-competent state until they are refolded by downstream ATP-dependent chaperone systems. Besides this interaction with unfolding substrates upon stress, sHsps show a different mode of binding for specific clients which are also recognized under physiological conditions. In vertebrates, sHsps are especially needed to maintain the refractive index of the eye lens. Additionally, sHsps are linked to a broad variety of diseases such as myopathies and neuropathies. The most striking feature of sHsps is their ability to form dynamic ensembles of higher oligomers. The activity of sHsps is regulated by changes in the composition of the ensembles.

scholarly journals Structural and functional homology between periplasmic bacterial molecular chaperones and small heat shock proteins

1995 ◽  
Vol 11 (4) ◽  
pp. 265-272 ◽  
Author(s):  
Vladimir P. Zav'yalov ◽  
Galina A. Zav'yalova ◽  
Alexander I. Denesyuk ◽  
Matthias Gaestel ◽  
Timo Korpela
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Small Heat Shock Proteins ◽  
Functional Homology ◽  
Shock Proteins

Cellular Functions and Mechanisms of Action of Small Heat Shock Proteins

2019 ◽  
Vol 73 (1) ◽  
pp. 89-110 ◽  
Author(s):  
Axel Mogk ◽  
Carmen Ruger-Herreros ◽  
Bernd Bukau
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Protein Unfolding ◽  
Small Heat Shock Proteins ◽  
Cellular Functions ◽  
Independent Manner ◽  
Cellular Defense ◽  
Shock Proteins ◽  
Substrate Binding Sites

Small heat shock proteins (sHsps) constitute a diverse chaperone family that shares the α-crystallin domain, which is flanked by variable, disordered N- and C-terminal extensions. sHsps act as the first line of cellular defense against protein unfolding stress. They form dynamic, large oligomers that represent inactive storage forms. Stress conditions cause a rapid increase in cellular sHsp levels and trigger conformational rearrangements, resulting in exposure of substrate-binding sites and sHsp activation. sHsps bind to early-unfolding intermediates of misfolding proteins in an ATP-independent manner and sequester them in sHsp/substrate complexes. Sequestration protects substrates from further uncontrolled aggregation and facilitates their refolding by ATP-dependent Hsp70-Hsp100 disaggregases. Some sHsps with particularly strong sequestrase activity, such as yeast Hsp42, are critical factors for forming large, microscopically visible deposition sites of misfolded proteins in vivo. These sites are organizing centers for triaging substrates to distinct quality control pathways, preferentially Hsp70-dependent refolding and selective autophagy.

scholarly journals A Novel Mechanism for Small Heat Shock Proteins to Function as Molecular Chaperones

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Kaiming Zhang ◽  
Anastasia N. Ezemaduka ◽  
Zhao Wang ◽  
Hongli Hu ◽  
Xiaodong Shi ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Small Heat Shock Proteins ◽  
Shock Proteins

scholarly journals Small heat shock proteins are molecular chaperones.

1993 ◽  
Vol 268 (3) ◽  
pp. 1517-1520 ◽  
Author(s):  
U. Jakob ◽  
M. Gaestel ◽  
K. Engel ◽  
J. Buchner
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Small Heat Shock Proteins ◽  
Shock Proteins

scholarly journals Molecular chaperones: Small heat shock proteins in the limelight

1999 ◽  
Vol 9 (3) ◽  
pp. R103-R105 ◽  
Author(s):  
Paul van den IJssel ◽  
David G. Norman ◽  
Roy A. Quinlan
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Small Heat Shock Proteins ◽  
Shock Proteins

Small heat shock proteins: recent developments

2013 ◽  
Vol 4 (6) ◽  
pp. 583-595 ◽  
Author(s):  
Benjamin Dennis Eisenhardt
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Elevated Temperatures ◽  
Higher Plants ◽  
Large Family ◽  
Small Heat Shock Proteins ◽  
Independent Manner ◽  
Physiological Relevance ◽  
Wide Range ◽  
Shock Proteins

AbstractSmall heat shock proteins (sHSPs) are abundantly present in many different organisms at elevated temperatures. Members of the subgroup of alpha crystallin domain (ACD)-type sHSPs belong to the large family of protein chaperones. They bind non-native proteins in an ATP-independent manner, thereby holding the incorporated clients soluble for subsequent refolding by other molecular chaperoning systems. sHSPs do not actively refold incorporated peptides therefore they are sometimes referred to as holdases. Varying numbers of sHSPs have been documented in the different domains of life and dependent on the analyzed organism. Generally, diverse sHSPs possess more sequence similarities in the conserved ACD, whereas the N- and C-terminal extensions are less conserved. Despite their designation as sHSPs, they are not solely present during heat stress. sHSPs presumably help to protect cells under various stresses, but they were also found during development, e.g., in embryonic development of higher plants which is associated with ongoing seed desiccation. The functional and physiological relevance of several different sHSPs in one organism remains still unclear, especially in plants where several highly similar sHSPs are present in the same compartment. The wide range of biotic and abiotic stresses that induce the expression of multiple sHSP genes makes it challenging to define the physiological relevance of each of these versatile proteins.

Sign in / Sign up

Export Citation Format

Share Document