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Literature summary for 7.4.2.3 extracted from

  • Schulz, C.; Rehling, P.
    Remodelling of the active presequence translocase drives motor-dependent mitochondrial protein translocation (2014), Nat. Commun., 5, 4349.
    View publication on PubMed
Search for more literature for 7.4.2.3

Activating Compound

Activating Compound Comment Organism Structure
additional information the soluble co-chaperone Mge1 stimulates ADP/ATP exchange Saccharomyces cerevisiae

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion
-
 Saccharomyces cerevisiae 5739
-

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ATP + H2O Saccharomyces cerevisiae
-
 ADP + phosphate
-
 ?

Organism

Organism UniProt Comment Textmining
Saccharomyces cerevisiae
-
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ATP + H2O
-
 Saccharomyces cerevisiae ADP + phosphate
-
 ?
additional information the active presequence translocase drives motor-dependent mitochondrial protein translocation Saccharomyces cerevisiae ?
-
 ?

Synonyms

Synonyms Comment Organism
mitochondrial hsp70
-
 Saccharomyces cerevisiae
mtHSP70
-
 Saccharomyces cerevisiae

General Information

General Information Comment Organism
malfunction temperature-sensitive mutants of mitochondrial Hsp70, affected in either ATP-binding and hydrolysis or Tim44 interaction, display defects in matrix protein import and concomitant TOM/TIM23-supercomplex formation when import reactions were performed under non-permissive conditions Saccharomyces cerevisiae
physiological function in mitochondria, matrix translocation of polypeptides depends on the ATP-powered mitochondrial Hsp70 (mtHsp70), the catalytic constituent of the presequence translocase-associated motor (PAM), at the trans side of the protein-conducting channel. mtHsp70 exists in a soluble pool mediating matrix protein folding and a TIM23-associated pool generating precursor velocity over the inner membrane. During precursor transport, a translocation intermediate is established in which the motor-associated, unfolded precursor simultaneously spans the TOM and TIM23 complexes thereby generating a mitochondrial contact site. For both activities, the soluble co-chaperone Mge1 stimulates ADP/ATP exchange. To drive precursor translocation, the Hsp70-import motor associates with the protein-conducting channel of the TIM23 complex, the ATPase cycle of Hsp70 is regulated in the context of a translocating polypeptide chain. The presence of all Hsp70 co-chaperones at the import channel is not sufficient to promote matrix protein import, instead a recharging of the active translocase with Pam18 is required for motor activity. Thus, a replenishment cycle of co-chaperones at the TIM23 complex is an integral part of Hsp70’s ATPase cycle at the channel exit site and essential to maintain motor-driven mitochondrial protein import. The association of the membrane-bound co-chaperones with the Tim23 channel unit is a prerequisite for the spatially controlled mtHsp70 regulation in mitochondria. Pam18 needs to be recharged at the translocase in order to maintain progressive mtHsp70 activity, such a replenishment cycle of the translocase’s co-chaperone Pam18 drives the ATP hydrolysis of the import motor in the precursor-occupied translocase and thus precursor transport along the presequence pathway, overview Saccharomyces cerevisiae