Chapter 21 General and exceptional pathways of protein import into sub-mitochondrial compartments

Lill, Roland; Hergersberg, Christoph; Schneider, Hans‐Jürgen; Söllner, Thomas H.; Stuart, Rosemary A.; Neupert, Walter

doi:10.1016/s0167-7306(08)60098-8

Cited by 4 publications

(5 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…No external energy sources like cytosolic or mitochondrial ATP were found to be required for import of all three known heme lyases. As a possibility for driving the import reaction, the specific folding of heme lyases in the intermembrane space seems possible (45). However, our data do not support this idea; they rather demonstrate that folding cannot be regarded as the energetic basis for the overall import process.…”

Section: Discussioncontrasting

confidence: 67%

Biogenesis of Mitochondrial Heme Lyases in Yeast

Steiner

Zollner

Haid

et al. 1995

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Heme lyases are components of the mitochondrial intermembrane space facilitating the covalent attachment of heme to the apoforms of c-type cytochromes. The precursors of heme lyases are synthesized in the cytosol without the typical N-terminal mitochondrial targeting signal. Here, we have analyzed the mode of import and folding of the two heme lyases of the yeast Saccharomyces cerevisiae, namely of cytochrome c heme lyase and of cytochrome c 1 heme lyase. For transport into mitochondria, both proteins use the general protein import machinery of the outer membrane. Import occurred independently of a membrane potential, ⌬, across the inner membrane and ATP in the matrix space, suggesting that the inner membrane is not required for transport along this direct sorting pathway. The presence of a large folded domain in heme lyases was utilized to study their folding in the intermembrane space. Formation of this domain occurred at the same rate as import, indicating that heme lyases fold either during or immediately after their transfer across the membrane. Folding was not affected by depletion of ATP and ⌬ or by inhibitors of peptidylprolyl cis-trans isomerases, i.e. it does not involve homologs of known folding factors (like Hsp60 and Hsp70). The energy derived from folding cannot be regarded as a major driving force for import, since the folded domain could be imported into mitochondria with the same efficiency as the intact protein. We conclude that protein folding in the intermembrane space obeys principles different from those established for other subcellular compartments.

show abstract

Section: Discussioncontrasting

confidence: 67%

Biogenesis of Mitochondrial Heme Lyases in Yeast

Steiner

Zollner

Haid

et al. 1995

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…The second type of chromophores comprising phycoviolobilin and phycourobilin, can not be added by the same mechanism, because their Δ3,4 double bond precludes a Δ3,3 1 double bond. The bound chromophores could principally arise from addition to a 3-vinyl group in the hypothetical free chromophores, similar to the addition of heme to c-type cytochromes ( , ), or the addition of thiols to vinyl-substituted bilins ( , ). However, no 3-vinyl chromophore has yet been isolated from the respective biliproteins.…”

mentioning

confidence: 99%

Chromophore Attachment to Biliproteins: Specificity of PecE/PecF, a Lyase-Isomerase for the Photoactive 3¹-Cys-α84-phycoviolobilin Chromophore of Phycoerythrocyanin

Storf¹,

Parbel²,

Meyer³

et al. 2001

Biochemistry

104

View full text Add to dashboard Cite

PecE and PecF, the products of two phycoerythrocyanin lyase genes (pecE and pecF) of Mastigocladus laminosus (Fischerella), catalyze two reactions: (1) the regiospecific addition of phycocyanobilin (PCB) to Cys-alpha 84 of the phycoerythrocyanin alpha-subunit (PecA), and (2) the Delta 4-->Delta 2 isomerization of the PCB to the phycoviolobilin (PVB)-chromophore [Zhao et al. (2000) FEBS Lett. 469, 9-13]. The alpha-apoprotein (PecA) as well PecE and PecF were overexpressed from two strains of M. laminosus, with and without His-tags. The products of the spontaneous addition of PCB to PecA, and that of the reaction catalyzed by PecE/F, were characterized by their photochemistry and by absorption, fluorescence, circular dichroism of the four states obtained by irradiation with light (15-Z/E isomers of the chromophore) and/or modification of Cys-alpha 98/99 with thiol-directed reagents. The spontaneous addition leads to a 3(1)-Cys-PCB adduct, which is characteristic of allophycocyanins and phycocyanins, while the addition catalyzed by PecE and PecF leads to a 3(1)-Cys-PVB adduct which after purification was identical to alpha-PEC. The specificity and kinetics of the chromophore additions were investigated with respect to the structure of the bilin substrate: The 3-ethylidene-bilins, viz., PCB, its 18-vinyl analogue phytochromobilin, phycoerythrobilin and its dimethylester, react spontaneously to yield the conventional addition products (3-H, 3(1)-Cys), while the 3-vinyl-substituted bilins, viz., bilirubin and biliverdin, were inactive. Only phycocyanobilin and phytochromobilin are substrates to the addition-isomerization reaction catalyzed by PecE/F. The slow spontaneous addition of phycoerythrobilin is not influenced, and there is in particular no catalyzed isomerization to urobilin.

show abstract

“…CCHL is also unusual in that it does not appear to require cytosolic hsp70 or the hydrolysis of free ATP to keep it competent for import. This might be due to a relatively extended conformation of the protein due to its unusually high content ofproline residues (12%) which might enable the protein to maintain an import-competent conformation even without the aid of chaperones (Lill et al, 1992a).…”

Section: The Transport Machineries Of the Inner And Outer Membrane Armentioning

confidence: 99%

“…CCHL resides in the intermembrane space close to the mitochondrial surface and may attach the heme group to apocytochrome c while the protein chain is still in transit (C. Hergersberg, unpublished). This might provide a driving force for the import of this exceptional protein (Lill et al, 1992a). On the other hand, it has been proposed that apocytochrome c can freely traverse the outer membrane into the intermembrane space, where it binds with high affinity to CCHL.…”

Section: The Transport Machineries Of the Inner And Outer Membrane Armentioning

confidence: 99%

Mitochondrial protein import: Specific recognition and membrane translocation of preproteins

et al. 1993

Self Cite

View full text Add to dashboard Cite

Chapter 21 General and exceptional pathways of protein import into sub-mitochondrial compartments

Cited by 4 publications

References 39 publications

Biogenesis of Mitochondrial Heme Lyases in Yeast

Biogenesis of Mitochondrial Heme Lyases in Yeast

Chromophore Attachment to Biliproteins: Specificity of PecE/PecF, a Lyase-Isomerase for the Photoactive 3¹-Cys-α84-phycoviolobilin Chromophore of Phycoerythrocyanin

Mitochondrial protein import: Specific recognition and membrane translocation of preproteins

Contact Info

Product

Resources

About

Chapter 21 General and exceptional pathways of protein import into sub-mitochondrial compartments

Cited by 4 publications

References 39 publications

Biogenesis of Mitochondrial Heme Lyases in Yeast

Biogenesis of Mitochondrial Heme Lyases in Yeast

Chromophore Attachment to Biliproteins: Specificity of PecE/PecF, a Lyase-Isomerase for the Photoactive 31-Cys-α84-phycoviolobilin Chromophore of Phycoerythrocyanin

Mitochondrial protein import: Specific recognition and membrane translocation of preproteins

Contact Info

Product

Resources

About

Chromophore Attachment to Biliproteins: Specificity of PecE/PecF, a Lyase-Isomerase for the Photoactive 3¹-Cys-α84-phycoviolobilin Chromophore of Phycoerythrocyanin