SecYEG assembles into a tetramer to form the active protein translocation channel

Manting, Erik H.; Does, Chris van der; Rémigy, Hervé W.; Engel, Andréas; Driessen, Arnold J.M.

doi:10.1093/emboj/19.5.852

Cited by 197 publications

(248 citation statements)

References 59 publications

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“…The distinct presence and absence of this dimeric signal peptide adduct, in the presence of AMP-PCP and ADP, respectively, suggests a possible SecA-signal peptide induced change in SecYEG dimerization at the time of the initial SecA membrane insertion step. This is consistent with the observations of Manting et al (22), using scanning transmission electron microscopy, that the membrane insertion of SecA induces tetramerization of SecYEG. Retraction of SecA upon ATP hydrolysis leaves the signal peptide bound to the monomeric SecYEG, in agreement with the reported crystal structure of SecYEG, in the absence of SecA, which suggests that the translocating polypeptide is likely held by monomeric SecYEG (24).…”

Section: Discussionsupporting

confidence: 93%

“…Electron microscopy of Bacillus subtilis SecYE reveals a ringlike structure in both detergent and reconstituted proteoliposomes (19). Though it is still unclear if one (20), two (21), or four (22) SecYEG complexes are involved in the formation of an active protein conducting channel, it has been shown that the oligomeric states of these complexes are dynamic. Three-dimensional electron image mapping of E. coli SecYEG complexes demonstrated a dimeric packing (23), yet the crystal structure of the translocon from Methanococcus jannaschii exhibited a monomeric SecY complex (24).…”

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confidence: 99%

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Demonstration of a Specific Escherichia coli SecY−Signal Peptide Interaction

et al. 2004

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Protein translocation in Escherichia coli is initiated by the interaction of a preprotein with the membrane translocase composed of a motor protein, SecA ATPase, and a membrane-embedded channel, the SecYEG complex. The extent to which the signal peptide region of the preprotein plays a role in SecYEG interactions is unclear, in part because studies in this area typically employ the entire preprotein. Using a synthetic signal peptide harboring a photoaffinity label in its hydrophobic core, we examined this interaction with SecYEG in a detergent micellar environment. The signal peptide was found to specifically bind SecY in a saturable manner and at levels comparable to those that stimulate SecA ATPase activity. Chemical and proteolytic cleavage of cross-linked SecY and analysis of the signal peptide adducts indicate that the binding was primarily to regions of the protein containing transmembrane domains seven and two. The signal peptide-SecY interaction was affected by the presence of SecA and nucleotides in a manner consistent with the transfer of signal peptide to SecY upon nucleotide hydrolysis at SecA. † This research was supported in part by National Institutes of Health Grant GM37639 (to D.A.K. Protein transport across, or integration into, biological membranes is a vital cellular process (1-3). Components of the Sec translocon, the membrane pore through which presecretory proteins (or membrane proteins) achieve membrane translocation (or integration), are the most conserved transport constituents throughout the three kingdoms of life (4).In Escherichia coli, the essential components of the translocase (5) include the membraneassociated form of SecA (6, 7) and the polytopic membrane proteins SecY, SecE (homologues of the mammalian Sec61α, Sec61γ, and the yeast ER 1 Sec61p, Sss1p, respectively), and SecG (8, 9); the latter three proteins form a stable trimeric SecYEG complex (10). SecA is an ATPase that powers the membrane translocation of hydrophilic polypeptides by coupling ATP hydrolysis with protein movement via concomitant SecA membrane insertion and deinsertion cycles (11,12). SecY protein has 10 transmembrane (TM1-TM10), six cytosolic (C1-C6), and five periplasmic (P1-P5) domains (13), and it forms the core of the passageway for the translocating polypeptide chain (14 (35,36). Suppressor analysis of prlA mutations using dysfunctional LamB signal peptides revealed that the suppressor mutations clustered in distinct regions, and TM7 of SecY was proposed to function in signal sequence recognition (37). Yet no investigation has focused on the direct interaction between a signal peptide and the E. coli translocon. Consequently, it remains unclear whether the nascent polypeptide chain is merely translocating in close proximity to SecY, SecY performs simply a proofreading function (37), or SecY is more intimately involved in the specific recognition of the signal peptide. Wang et al. Page 2Biochemistry. Author manuscript; available in PMC 2011 April 29. NIH-PA Author ManuscriptNIH-PA Author Manuscr...

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Section: Discussionsupporting

confidence: 93%

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confidence: 99%

Demonstration of a Specific Escherichia coli SecY−Signal Peptide Interaction

et al. 2004

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“…Sec(YEG) 4 ). 23 Furthermore, arrested translocation reactions were found to contain particles of mass 531 and 686 kDa, which are thought to comprise preprotein substrate, SecA dimer, and either two or four SecYEG heterotrimers. On the other hand, there is biochemical evidence that the active translocon contains only a monomeric SecYEG complex.…”

Section: Introductionmentioning

confidence: 99%

“…41,42 There is evidence that SecYEG also forms tetramers during active translocation. 23 SecA protomer-protomer interactions may be important in the assembly and regulation of the active translocation complex. To develop these ideas further, we have carried out a detailed study of the oligomerization and overall shape of the isolated N-terminal ATPase domain from Escherichia coli SecA.…”

Section: Introductionmentioning

confidence: 99%

The ATPase domain of SecA can form a tetramer in solution 1 1Edited by I. B. Holland

Dempsey

Economou

Dunn

et al. 2002

Journal of Molecular Biology

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“…7). The active state of the preprotein-conducting channel has been proposed to consist of a SecA dimer bound to a tetrameric SecYEG complex 22 . In view of the symmetry of the SecA-SecB interaction, it seems plausible that the oligomeric SecYEG channel accepts one preprotein at a time from a SecA-SecB pair.…”

Section: Research Updatementioning

confidence: 99%