Global Co-ordination of Protein Translocation by the SecA IRA1 Switch

Vrontou, Eleftheria; Karamanou, Spyridoula; Baud, C.; Sianidis, Giorgos; Economou, Anastassios

doi:10.1074/jbc.m401008200

Cited by 53 publications

(110 citation statements)

References 40 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…They also identified another region that had synergistic effects, and termed it IRA2 and the first segment IRA1. 69,70 IRA2, in fact, is the second helicase domain, which was clear once the crystal structure was available.…”

Section: Seca Is Central To the Bacterial Sec Pathwaymentioning

confidence: 98%

“…Studies from a variety of groups over the past decade have revealed that SecA is a multidomain protein that can exist as a monomer or a dimer, and that its domain rearrangements can be triggered by binding to any of its several ligands. 67,[69][70][71][72][73][74][75][76][77][78][79][80][81] The key to the conformational rearrangements appears to be intramolecular interactions that stabilize a more tightly packed, ''closed'' form of the protein. Weakening these interactions relieves these intramolecular constraints, and the protein domains partially dissociate, creating a less tightly packed, ''open'' form of the protein.…”

Section: Seca Is Central To the Bacterial Sec Pathwaymentioning

confidence: 99%

See 1 more Smart Citation

Use of synthetic signal sequences to explore the protein export machinery

Clérico¹,

Maki²,

Gierasch³

2008

Biopolymers

View full text Add to dashboard Cite

The information for correct localization of newly synthesized proteins in both prokaryotes and eukaryotes resides in self‐contained, often transportable targeting sequences. Of these, signal sequences specify that a protein should be secreted from a cell or incorporated into the cytoplasmic membrane. A central puzzle is presented by the lack of primary structural homology among signal sequences, although they share common features in their sequences. Synthetic signal peptides have enabled a wide range of studies of how these “zipcodes” for protein secretion are decoded and used to target proteins to the protein machinery that facilitates their translocation across and integration into membranes. We review research on how the information in signal sequences enables their passenger proteins to be correctly and efficiently localized. Synthetic signal peptides have made possible binding and crosslinking studies to explore how selectivity is achieved in recognition by the signal sequence‐binding receptors, signal recognition particle, or SRP, which functions in all organisms, and SecA, which functions in prokaryotes and some organelles of prokaryotic origins. While progress has been made, the absence of atomic resolution structures for complexes of signal peptides and their receptors has definitely left many questions to be answered in the future. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 307–319, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

show abstract

Section: Seca Is Central To the Bacterial Sec Pathwaymentioning

confidence: 98%

Section: Seca Is Central To the Bacterial Sec Pathwaymentioning

confidence: 99%

Use of synthetic signal sequences to explore the protein export machinery

Clérico¹,

Maki²,

Gierasch³

2008

Biopolymers

View full text Add to dashboard Cite

show abstract

“…These results as well as the results of Dapic and Oliver (37) that a N-terminal fragment of SecA is sufficient for the high affinity binding to SecYEG are consistent with our proposal made in this work that the ATPase itself can sense SecYEG as an activating ligand. The maximum ATPase up-regulation, which requires preprotein binding as well, must be accompanied by a substantial conformational change of the ATPase domain (32) to facilitate the arginine finger access to the ATP ␥-phosphate and possibly to induce the swinging movement of HSD.…”

Section: Discussionmentioning

confidence: 99%

The Long α-Helix of SecA Is Important for the ATPase Coupling of Translocation

Mori

Ito

2006

Journal of Biological Chemistry

View full text Add to dashboard Cite

SecA contains two ATPase folds (NBF1 and NBF2) and other interaction/regulatory domains, all of which are connected by a long helical scaffold domain (HSD) running along the molecule. Here we identified a functionally important and spatially adjacent pair of SecA residues, Arg-642 on HSD and Glu-400 on NBF1. A charge-reversing substitution at either position as well as disulfide tethering of these positions inactivated the translocation activity. Interestingly, however, the translocation-inactive SecA variants fully retained the ability to up-regulate the ATPase in response to a preprotein and the SecYEG translocon. The translocation defect was suppressible by second site alterations at the hinge-forming boundary of NBF2 and HSD. Based on these results, we propose that the motor function of SecA is realized by ligand-activated ATPase engine and its HSD-mediated conversion into the mechanical work of preprotein translocation.

show abstract

“…Tyr-326 has been found to be critical in controlling . An N-terminally truncated SecA, representing the activated state, has been found to have high ATPase activity, binds the signal peptide with significantly higher affinity than WT SecA, and exists in a monomeric form (8,35). This suggests that the affinity of the signal peptide for SecA depends on its conformational state (36).…”

Section: Introductionmentioning

confidence: 99%

Probing the Affinity of SecA for Signal Peptide in Different Environments

2005

View full text Add to dashboard Cite

SecA, the peripheral subunit of the Escherichia coli preprotein translocase, interacts with a number of ligands during export, including signal peptides, membrane phospholipids, and nucleotides. Using fluorescence resonance energy transfer (FRET), we studied the interactions of wild-type (WT) and mutant SecAs with IAEDANS-labeled signal peptide, and how these interactions are modified in the presence of other transport ligands. We find that residues on the third α-helix in the preprotein cross-linking domain (PPXD) are important for the interaction of SecA and signal peptide. For SecA in aqueous solution, saturation binding data using FRET analysis fit a single-site binding model and yielded a K d of 2.4 μM. FRET is inhibited for SecA in lipid vesicles relative to that in aqueous solution at a low signal peptide concentration. The sigmoidal nature of the binding curve suggests that SecA in lipids has two conformational states; our results do not support different oligomeric states of SecA. Using native gel electrophoresis, we establish signal peptide-induced SecA monomerization in both aqueous solution and lipid vesicles. Whereas the affinity of SecA for signal peptide in an aqueous environment is unaffected by temperature or the presence of nucleotides, in lipids the affinity decreases in the presence of ADP or AMP-PCP but increases at higher temperature. The latter finding is consistent with SecA existing in an elongated form while inserting the signal peptide into membranes.More than one-third of the proteins synthesized inside the cell must be exported to extracytoplasmic locations to perform their functions. In Escherichia coli, many preproteins are recognized and transported by the Sec transport machinery. This secretory pathway has been extensively studied and several of the key proteins involved have been identified and characterized; however, the mechanisms by which the preprotein interacts with the secretion machinery are not clearly understood.In the cytoplasm, SecB, a chaperone, binds preproteins to keep them in an unfolded state and delivers them to the membrane-associated SecA for post-translational export (1, 2). SecA is a critical component of the Sec transport pathway; it recognizes and binds the preprotein and functions as an ATPase. Moreover, conformational changes resulting from the interaction of SecB with SecA are thought to result in the transfer of the preprotein from the chaperone to the ATPase (3, 4). The membrane proteins, SecG, SecD, and SecF, stabilize and stimulate SecA at the membrane, and as a consequence, SecA can deliver the preprotein through the SecYEG pore (5, 6). Some studies indicate binding of ATP causes the dissociation of SecB from the enzyme, and cycles of ATP hydrolysis (7,8) and conformational changes lead to membrane insertion of the SecA-preprotein complex followed by deinsertion of SecA (9, 10). Meyer et al. (11) One SecA dimerization site is located at its C-terminus (18), which also binds SecY, SecB, and phospholipids (23), and not surprisingly, these a...

show abstract

Global Co-ordination of Protein Translocation by the SecA IRA1 Switch

Cited by 53 publications

References 40 publications

Use of synthetic signal sequences to explore the protein export machinery

Use of synthetic signal sequences to explore the protein export machinery

The Long α-Helix of SecA Is Important for the ATPase Coupling of Translocation

Probing the Affinity of SecA for Signal Peptide in Different Environments

Contact Info

Product

Resources

About