The C Terminus of SecA Is Involved in Both Lipid Binding and SecB Binding

Breukink, Eefjan; Nouwen, Nico; Raalte, Anne van; Mizushima, Shôji; Tommassen, Jan; Kruijff, Ben de

doi:10.1074/jbc.270.14.7902

Cited by 149 publications

(182 citation statements)

References 39 publications

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“…Within the SecB tetramer, four such regions would be present and together they could form the binding sites for the preprotein and SecA. The SecB-binding site on SecA is localized in the carboxyl terminus [12] and corresponds to the last 22 aminoacyl residues of SecA [13"*]. This domain contains a high amount of glycyl, prolyl and cysteinyl residues and has a net positive charge, opposite in charge to the site of SecA binding on SecB.…”

Section: Preprotein Targeting To the Membrane Secb Recognition Sites mentioning

confidence: 99%

The Sec system

Driessen

Fekkes

Wolk

1998

Current Opinion in Microbiology

159

111

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The Sec system Driessen, A.J.M.; Fekkes, P.; van der Wolk, J.P.W. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Proteins designated to be secreted by Escherichia coil are synthesized with an amino-terminal signal peptide and associate as nascent chains with the export-specific chaperone SecB. Translocation occurs at a multisubunit membrane-bound enzyme termed translocase, which consists of a peripheral preprotein-binding site and an ATPase domain termed SecA, a core heterotrimeric integral membrane protein complex with SecY, SecE and SecG as subunits, and an accessory integral membrane protein complex containing SecD and SecE Major new insights have been gained into the cascade of preprotein targeting events and the enzymatic mechanism of preprotein translocation. It has become clear that preproteins are translocated in a stepwise fashion involving large nucleotide-induced conformational changes of the molecular motor SecA that propels the translocation reaction. Addresses

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Section: Preprotein Targeting To the Membrane Secb Recognition Sites mentioning

confidence: 99%

The Sec system

Driessen

Fekkes

Wolk

1998

Current Opinion in Microbiology

159

111

View full text Add to dashboard Cite

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“…SecB is a molecular chaperone that binds to a subset of precursor proteins, thereby preventing them from aggregating (Kumamoto, 1990). The affinity of SecB for the C-terminus of SecA plays an important role in the correct targeting of the precursor protein to the translocase (Breukink et al, 1995). SecB is active as a tetramer and is highly selective towards its substrates.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of SecB from Escherichia coli

Dekker

Kruijff

Gros

2003

Journal of Structural Biology

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The chaperone SecB from Escherichia coli is primarily involved in passing precursor proteins into the Sec system via specific interactions with SecA. The crystal structure of SecB from E. coli has been solved to 2.35 A A resolution. The structure shows flexibility in the crossover loop and the helix-connecting loop, regions that have been implicated to be part of the SecB substrate-binding site. Moreover conformational variability of Trp36 is observed as well as different loop conformations for the different monomers. Based on this, we speculate that SecB can regulate the access or extent of its hydrophobic substrate-binding site, by modulating the conformation of the crossover loop and the helix-connecting loop. The structure also clearly explains why the tetrameric equilibrium is shifted towards the dimeric state in the mutant SecBCys76Tyr. The buried cysteine residue is crucial for tight packing, and mutations are likely to disrupt the tetramer formation but not the dimer formation.

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“…1A) (18,19): the scaffold domain (SD), a 46-aalong bent ␣-helix, which docks the C-domain to the DEAD motor by acting as a molecular staple binding both NBD and IRA2; the flexible wing domain (WD); IRA1 (15), a conserved helix-loophelix (H1-L-H2) that fits between SD and SSD (Fig. 5); and the extreme C-terminal region (CTD), which is largely crystallographically unresolved and binds lipid and SecB (26,27).…”

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confidence: 99%

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

Vrontou

Karamanou

Baud

et al. 2004

Journal of Biological Chemistry

106

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SecA, the dimeric ATPase subunit of protein translocase, contains a DEAD helicase catalytic core that binds to a regulatory C-terminal domain. We now demonstrate that IRA1, a conserved helix-loop-helix structure in the C-domain, controls C-domain conformation through direct interdomain contacts. C-domain conformational changes are transmitted to the DEAD motor and alter its conformation. These interactions establish DEAD motor/C-domain conformational cross-talk that requires a functional IRA1. IRA1-controlled binding/release cycles of the C-domain to the DEAD motor couple this crosstalk to protein translocation chemistries, i.e. DEAD motor affinities for ligands (nucleotides, preprotein signal peptides, and SecYEG, the integral membrane component of translocase) and ATP turnover. IRA1-mediated global co-ordination of SecA catalysis is essential for protein translocation.

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The C Terminus of SecA Is Involved in Both Lipid Binding and SecB Binding

Cited by 149 publications

References 39 publications

The Sec system

The Sec system

Crystal structure of SecB from Escherichia coli

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

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