scholarly journals Protein Export across the Inner Membrane of Mitochondria

2003 ◽  
Vol 279 (4) ◽  
pp. 2507-2512 ◽  
Author(s):  
Johannes M. Herrmann ◽  
Nathalie Bonnefoy
Keyword(s):  
Protein Export ◽  
Inner Membrane

scholarly journals SecA—a New Twist in the Tale

2016 ◽  
Vol 199 (2) ◽  
Author(s):  
Ian Collinson
Keyword(s):  
Secretion System ◽  
Protein Export ◽  
Inner Membrane ◽  
Link Type ◽  
Sec System ◽  
Bacterial Secretion ◽  
Bacterial Secretion System ◽  
Timely Reminder

ABSTRACT A paper published in this issue of the Journal of Bacteriology (D. Huber, M. Jamshad, R. Hanmer, D. Schibich, K. Döring, I. Marcomini, G. Kramer, and B. Bukau, J Bacteriol 199:e0622-16, 2017, https://doi.org/10.1128/JB.00622-16 ) provides us with a timely reminder that all is not as clear as we had previously thought in the general bacterial secretion system. The paper describes a new mode of secretion through the Sec system—“uncoupled cotranslocation”—for the passage of proteins across the bacterial inner membrane and suggests that we might rethink the nature and mechanism of the targeting and transport steps toward protein export.

scholarly journals Mba1, a Novel Component of the Mitochondrial Protein Export Machinery of the Yeast Saccharomyces cerevisiae

2001 ◽  
Vol 153 (5) ◽  
pp. 1085-1096 ◽  
Author(s):  
Marc Preuss ◽  
Klaus Leonhard ◽  
Kai Hell ◽  
Rosemary A. Stuart ◽  
Walter Neupert ◽  
...  
Keyword(s):  
Mitochondrial Protein ◽  
Protein Export ◽  
Mitochondrial Translation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Inner Membrane ◽  
Protein Insertion ◽  
Mitochondrial Inner Membrane ◽  
The Matrix ◽  
Biogenesis Of Mitochondria ◽  
Inner Membrane Protein

The biogenesis of mitochondria requires the integration of many proteins into the inner membrane from the matrix side. The inner membrane protein Oxa1 plays an important role in this process. We identified Mba1 as a second mitochondrial component that is required for efficient protein insertion. Like Oxa1, Mba1 specifically interacts both with mitochondrial translation products and with conservatively sorted, nuclear-encoded proteins during their integration into the inner membrane. Oxa1 and Mba1 overlap in function and substrate specificity, but both can act independently of each other. We conclude that Mba1 is part of the mitochondrial protein export machinery and represents the first component of a novel Oxa1-independent insertion pathway into the mitochondrial inner membrane.

scholarly journals Fates of Sec, Tat, and YidC Translocases in Mitochondria and Other Eukaryotic Compartments

2021 ◽  
Author(s):  
Markéta Petrů ◽  
Vít Dohnálek ◽  
Zoltán Füssy ◽  
Pavel Doležal
Keyword(s):  
Genetic Control ◽  
Mitochondrial Function ◽  
Protein Export ◽  
The Other ◽  
Mitochondrial Proteins ◽  
Endomembrane System ◽  
Inner Membrane ◽  
Bacterial Endosymbiont ◽  
Single Substrate ◽  
Host Nucleus

Abstract Formation of mitochondria by the conversion of a bacterial endosymbiont was a key moment in the evolution of eukaryotes. It was made possible by outsourcing the endosymbiont’s genetic control to the host nucleus, while developing the import machinery for proteins synthesized on cytosolic ribosomes. The original protein export machines of the nascent organelle remained to be repurposed or were completely abandoned. This review follows the evolutionary fates of three prokaryotic inner membrane translocases Sec, Tat, and YidC. Homologs of all three translocases can still be found in current mitochondria, but with different importance for mitochondrial function. Although the mitochondrial YidC homolog, Oxa1, became an omnipresent independent insertase, the other two remained only sporadically present in mitochondria. Only a single substrate is known for the mitochondrial Tat and no function has yet been assigned for the mitochondrial Sec. Finally, this review compares these ancestral mitochondrial proteins with their paralogs operating in the plastids and the endomembrane system.

scholarly journals secG and Temperature Modulate Expression of Azide-Resistant and Signal Sequence Suppressor Phenotypes of Escherichia coli secA Mutants

1998 ◽  
Vol 180 (23) ◽  
pp. 6419-6423 ◽  
Author(s):  
Visvanathan Ramamurthy ◽  
Vesna Dapíc ◽  
Donald Oliver
Keyword(s):  
Escherichia Coli ◽  
Direct Effect ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Protein Export ◽  
Null Mutant ◽  
Inner Membrane ◽  
Membrane Interaction ◽  
Cold Sensitive ◽  
Azide Resistance

ABSTRACT SecA is a dynamic protein that undergoes ATP-dependent membrane cycling to drive protein translocation across the Escherichia coli inner membrane. To understand more about this process, azide-resistant (azi) and signal sequence suppressor (prlD) alleles of secA were studied. We found that azide resistance is cold sensitive because of a direct effect on protein export, suggesting that SecA-membrane interaction is regulated by an endothermic step that is azide inhibitable. secGfunction is required for expression of azide-resistant and signal sequence suppressor activities of azi and prlDalleles, and in turn, these alleles suppress cold-sensitive and export-defective phenotypes of a secG null mutant. These remarkable genetic observations support biochemical data indicating that SecG promotes SecA membrane cycling and that this process is dependent on an endothermic change in SecA conformation.

scholarly journals The Structure of Multiple Polypeptide Domains Determines the Signal Recognition Particle Targeting Requirement ofEscherichia coli Inner Membrane Proteins

1999 ◽  
Vol 181 (15) ◽  
pp. 4561-4567 ◽  
Author(s):  
John A. Newitt ◽  
Nancy D. Ulbrandt ◽  
Harris D. Bernstein
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Membrane Proteins ◽  
Signal Recognition Particle ◽  
Protein Export ◽  
Signal Recognition ◽  
Inner Membrane ◽  
Periplasmic Domain ◽  
Membrane Spanning ◽  
Membrane Spanning Domains

ABSTRACT The signal recognition particle (SRP) targeting pathway is required for the efficient insertion of many polytopic inner membrane proteins (IMPs) into the Escherichia coli inner membrane, but in the absence of SRP protein export proceeds normally. To define the properties of IMPs that impose SRP dependence, we analyzed the targeting requirements of bitopic IMPs that are structurally intermediate between exported proteins and polytopic IMPs. We found that disruption of the SRP pathway inhibited the insertion of only a subset of bitopic IMPs. Studies on a model bitopic AcrB-alkaline phosphatase fusion protein (AcrB 265-AP) showed that the SRP requirement for efficient insertion correlated with the presence of a large periplasmic domain (P1). As previously reported, perturbation of the SRP pathway also affected the insertion of a polytopic AcrB-AP fusion. Even exhaustive SRP depletion, however, failed to block the insertion of any AcrB derivative by more than 50%. Taken together, these data suggest that many proteins that are normally targeted by SRP can utilize alternative targeting pathways and that the structure of both hydrophilic and membrane-spanning domains determines the degree to which the biogenesis of a protein is SRP dependent.

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