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Literature summary for 3.6.4.10 extracted from

  • Flores-Perez, U.; Jarvis, P.
    Molecular chaperone involvement in chloroplast protein import (2013), Biochim. Biophys. Acta, 1833, 332-340.
    View publication on PubMed

Protein Variants

Protein Variants Comment Organism
additional information consstruction of a temperature-sensitive hsp70-2 knockout mutant Physcomitrium patens

Localization

Localization Comment Organism GeneOntology No. Textmining
chloroplast
-
Arabidopsis thaliana 9507
-
chloroplast intermembrane space of chloroplast envelope membranes Arabidopsis thaliana 31972
-
chloroplast membrane three pea chloroplastic Hsp70 isoforms, of which two are soluble proteins located in the stroma, and one isoform, termed imsHsp70 isoform, is tightly associated to the outer membrane but not exposed at the outer surface of the chloroplasts Pisum sativum 31969
-
chloroplast stroma associated to the membrane channel of the inner envelope membrane, at the stromal side Physcomitrium patens 9570
-
chloroplast stroma three pea chloroplastic Hsp70 isoforms, of which two are soluble proteins located in the stroma, and one isoform, termed imsHsp70 isoform, is tightly associated to the outer membrane but not exposed at the outer surface of the chloroplasts Pisum sativum 9570
-
cytosol
-
Arabidopsis thaliana 5829
-
additional information three putative chloroplastic Hsp70 isozymes, two of them, AtHsp70-6 and AtHsp70-7 (alternatively called cpHsc70-1 and cpHsc70-2, respectively, for chloroplast Heat shock cognate protein, 70 kD) are localized in the soluble fraction of chloroplasts while the third, AtHsp70-8, is not even imported into chloroplasts in vitro Arabidopsis thaliana
-
-

Metals/Ions

Metals/Ions Comment Organism Structure
Mg2+ required Pisum sativum
Mg2+ required Physcomitrium patens
Mg2+ required Arabidopsis thaliana

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ATP + H2O Pisum sativum
-
ADP + phosphate
-
?
ATP + H2O Physcomitrium patens
-
ADP + phosphate
-
?
ATP + H2O Arabidopsis thaliana
-
ADP + phosphate
-
?
additional information Pisum sativum the imsHsp70 isoform is supposed to interact with translocating preproteins in pea chloroplasts ?
-
?

Organism

Organism UniProt Comment Textmining
Arabidopsis thaliana P22953 isoform Hsp70-1; isoform Hsp70-1
-
Arabidopsis thaliana P22954 isoform Hsp70-2; isoform Hsp70-2
-
Physcomitrium patens
-
isoform Hsp70-3
-
Physcomitrium patens D2XNF3 isoform Hsp70-1; isoform Hsp70-1
-
Physcomitrium patens D2XNF4 isoform Hsp70-2; isoform Hsp70-2
-
Pisum sativum
-
three isoforms of Hsp70
-

Source Tissue

Source Tissue Comment Organism Textmining
leaf
-
Pisum sativum
-
leaf
-
Arabidopsis thaliana
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ATP + H2O
-
Pisum sativum ADP + phosphate
-
?
ATP + H2O
-
Physcomitrium patens ADP + phosphate
-
?
ATP + H2O
-
Arabidopsis thaliana ADP + phosphate
-
?
additional information the imsHsp70 isoform is supposed to interact with translocating preproteins in pea chloroplasts Pisum sativum ?
-
?

Subunits

Subunits Comment Organism
More unlike Hsp100s, Hsp70-type chaperones do not oligomerize. They transiently associate with exposed hydrophobic segments of client proteins via a carboxy-terminal substrate binding domain (SBD), thereby preventing aggregation and promoting proper folding Pisum sativum
More unlike Hsp100s, Hsp70-type chaperones do not oligomerize. They transiently associate with exposed hydrophobic segments of client proteins via a carboxy-terminal substrate binding domain (SBD), thereby preventing aggregation and promoting proper folding Physcomitrium patens
More unlike Hsp100s, Hsp70-type chaperones do not oligomerize. They transiently associate with exposed hydrophobic segments of client proteins via a carboxy-terminal substrate binding domain (SBD), thereby preventing aggregation and promoting proper folding Arabidopsis thaliana

Synonyms

Synonyms Comment Organism
Hsp70
-
Pisum sativum
Hsp70
-
Physcomitrium patens
Hsp70
-
Arabidopsis thaliana
Hsp70-1
-
Arabidopsis thaliana
Hsp70-1
-
Physcomitrium patens
Hsp70-2
-
Arabidopsis thaliana
Hsp70-2
-
Physcomitrium patens
Hsp70-3
-
Physcomitrium patens

Cofactor

Cofactor Comment Organism Structure
additional information Hsp70s invariably require a J-domain protein and, almost always, a nucleotide exchange factor (e.g., GrpE) as partners in order to be completely functional Pisum sativum
additional information Hsp70s invariably require a J-domain protein and, almost always, a nucleotide exchange factor (e.g., GrpE) as partners in order to be completely functional Physcomitrium patens
additional information Hsp70s invariably require a J-domain protein and, almost always, a nucleotide exchange factor (e.g., GrpE) as partners in order to be completely functional Arabidopsis thaliana

General Information

General Information Comment Organism
evolution chloroplast stromal Hsp70s are believed to exist in a variety of plant species, including Arabidopsis, pea, poplar, rice, sorghum and moss Pisum sativum
evolution chloroplast stromal Hsp70s are believed to exist in a variety of plant species, including Arabidopsis, pea, poplar, rice, sorghum and moss Physcomitrium patens
evolution chloroplast stromal Hsp70s are believed to exist in a variety of plant species, including Arabidopsis, pea, poplar, rice, sorghum and moss Arabidopsis thaliana
malfunction the Arabidopsis Hsp70 knockout mutant cpshsc70-1 shows that stromal Hsp70 is important for the import of both photosynthetic and non-photosynthetic precursor proteins, especially at early developmental stages Arabidopsis thaliana
malfunction the Arabidopsis Hsp70 knockout mutant cpshsc70-2 shows that stromal Hsp70 is important for the import of both photosynthetic and non-photosynthetic precursor proteins, especially at early developmental stages Arabidopsis thaliana
metabolism several chaperones and cochaperones mediate different stages of chloroplast import of preproteins, which are in a largely unfolded state. Cytosolic factors such as Hsp90, Hsp70 and 14-3-3 may assist preproteins to reach the TOC complex, i.e. translocon at the outer envelope membrane of chloroplasts complex, at the chloroplast surface, preventing their aggregation or degradation. Chaperones may also be involved in the intermembrane space transport. Preprotein translocation is completed at the trans side of the inner membrane by ATP-driven motor complexes. A stromal Hsp100-type chaperone, Hsp93, cooperates with Tic110 and Tic40 in one such motor complex, while stromal Hsp70 is proposed to act in a second, parallel complex. Upon arrival in the stroma, chaperones (e.g., Hsp70, Cpn60, cpSRP43) also contribute to the folding, assembly or onward intraorganellar guidance of the proteins. Chaperone involvement in the stroma during chloroplast protein import, modeling, detailed overview Pisum sativum
metabolism several chaperones and cochaperones mediate different stages of chloroplast import of preproteins, which are in a largely unfolded state. Cytosolic factors such as Hsp90, Hsp70 and 14-3-3 may assist preproteins to reach the TOC complex, i.e. translocon at the outer envelope membrane of chloroplasts complex, at the chloroplast surface, preventing their aggregation or degradation. Chaperones may also be involved in the intermembrane space transport. Preprotein translocation is completed at the trans side of the inner membrane by ATP-driven motor complexes. A stromal Hsp100-type chaperone, Hsp93, cooperates with Tic110 and Tic40 in one such motor complex, while stromal Hsp70 is proposed to act in a second, parallel complex. Upon arrival in the stroma, chaperones (e.g., Hsp70, Cpn60, cpSRP43) also contribute to the folding, assembly or onward intraorganellar guidance of the proteins. Chaperone involvement in the stroma during chloroplast protein import, modeling, detailed overview Physcomitrium patens
metabolism several chaperones and cochaperones mediate different stages of chloroplast import of preproteins, which are in a largely unfolded state. Cytosolic factors such as Hsp90, Hsp70 and 14-3-3 may assist preproteins to reach the TOC complex, i.e. translocon at the outer envelope membrane of chloroplasts complex, at the chloroplast surface, preventing their aggregation or degradation. Chaperones may also be involved in the intermembrane space transport. Preprotein translocation is completed at the trans side of the inner membrane by ATP-driven motor complexes. A stromal Hsp100-type chaperone, Hsp93, cooperates with Tic110 and Tic40 in one such motor complex, while stromal Hsp70 is proposed to act in a second, parallel complex. Upon arrival in the stroma, chaperones (e.g., Hsp70, Cpn60, cpSRP43) also contribute to the folding, assembly or onward intraorganellar guidance of the proteins. Chaperone involvement in the stroma during chloroplast protein import, modeling, detailed overview Arabidopsis thaliana
additional information isoform Hsp70-1 cannot substitute the loss of Hsp70-2 despite their high degree of similarity Physcomitrium patens
additional information isoform Hsp70-3 cannot substitute the loss of Hsp70-2 despite their high degree of similarity Physcomitrium patens
additional information isolated chloroplasts containing the temperature-sensitive Hsp70-2 protein display lower import competence after heat-shock treatment, when compared with wild-type chloroplasts. Neither of the other two isoforms, Hsp70-1 and Hsp70-3, can substitute the loss of Hsp70-2 despite their high degree of similarity Physcomitrium patens
physiological function Hsp70 is involved in te chloroplast import of preproteins. It may form a guidance complex together with 14-3-3 that delivers phosphorylated preproteins to the Toc34 receptor. Hsp70 is also proposed to deliver preproteins to the OEP61 protein Arabidopsis thaliana
physiological function Hsp70 is involved in te chloroplast import of preproteins. Stromal Hsp70 might provide the driving force in chloroplast protein import Pisum sativum
physiological function Hsp70 is involved in te chloroplast import of preproteins. Stromal Hsp70 might provide the driving force in chloroplast protein import Physcomitrium patens
physiological function Hsp70 is involved in te chloroplast import of preproteins. Stromal Hsp70 might provide the driving force in chloroplast protein import. It may form a guidance complex together with 14-3-3 that delivers phosphorylated preproteins to the Toc34 receptor. Hsp70 is also proposed to deliver preproteins to the OEP61 protein Arabidopsis thaliana
physiological function Hsp70 is involved in the chloroplast import of preproteins. Stromal Hsp70 might provide the driving force in chloroplast protein import Arabidopsis thaliana