Stoichiometry of SecYEG in the active translocase of
            <i>Escherichia coli</i>
            varies with precursor species

Mao, Chunfeng; Cheadle, Carl; Hardy, Simon; Lilly, Angela A.; Suo, Yang; Gari, Raghavendar Reddy Sanganna; King, Gavin M.; Randall, Linda L.

doi:10.1073/pnas.1303289110

Cited by 40 publications

(85 citation statements)

References 45 publications

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“…These observations suggest that the bacteria rearrange translocon composition and/or stoichiometry in order to adapt to the hypersecretion state during infection. In this regard it was shown recently that the translocon stoichiometry varies upon translocation of different precursors, for example, outer membrane versus periplasmic protein (49). In light of these findings and the numerous reports that the SecYEG translocon can be found in various types of oligomers (50)(51)(52), it is tempting to speculate that bacteria modify the composition and/or the stoichiometry of the translocon apparatuses as a mechanism to cope with different secretion/translocation requirements.…”

Section: Discussionmentioning

confidence: 99%

Membrane Chaperone SecDF Plays a Role in the Secretion of Listeria monocytogenes Major Virulence Factors

Tamar

Pozniak

Rabinovich

et al. 2013

Journal of Bacteriology

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Listeria monocytogenes is a Gram-positive human intracellular pathogen that infects diverse mammalian cells. Upon invasion, L. monocytogenes secretes multiple virulence factors that target host cellular processes and promote infection. It has been presumed, but was not empirically established, that the Sec translocation system is the primary mediator of this secretion. Here, we validate an important role for SecDF, a component of the Sec system, in the secretion of several critical L. monocytogenes virulence factors. A ⌬secDF mutant is demonstrated to exhibit impaired membrane translocation of listeriolysin O (LLO), PlcA, PlcB, and ActA, factors that mediate L. monocytogenes phagosomal escape and spread from cell to cell. This impaired translocation was monitored by accumulation of the factors on the bacterial membrane and by reduced activity upon secretion. This defect in secretion is shown to be associated with a severe intracellular growth defect of the ⌬secDF mutant in macrophages and a less virulent phenotype in mice, despite normal growth in laboratory medium. We further show that SecDF is upregulated when the bacteria reside in macrophage phagosomes and that it is necessary for efficient phagosomal escape. Taken together, these data support the premise that SecDF plays a role as a chaperone that facilitates the translocation of L. monocytogenes virulence factors during infection.

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Section: Discussionmentioning

confidence: 99%

Membrane Chaperone SecDF Plays a Role in the Secretion of Listeria monocytogenes Major Virulence Factors

Tamar

Pozniak

Rabinovich

et al. 2013

Journal of Bacteriology

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“…Perhaps, dimerization allows SecYEG to transit from a resting state to a translocation-ready state, characterized by greater SecA binding affinity (20) and more flexibility of the plug domain to accommodate preprotein (10). Interestingly, a recent study hints at a more subtle type of dimer function where the nature of the preprotein substrate may determine whether transport occurs via a SecYEG monomer or dimer (31). This phenomenon points to a possible structural signal within particular substrate proteins that facilitates dimer formation.…”

Section: Discussionmentioning

confidence: 99%

“…These authors also functionally disrupted SecY dimer assembly by mutagenesis at the dimer interface, further supporting the functional monomer view. Adding to the ongoing controversy, a recent study utilizing a highly efficient SecYEG reconstitution system found that preproteins apparently differed in their translocon stoichiometry requirement, where a monomer or dimer was required depending on the preprotein species under study (31).…”

mentioning

confidence: 99%

Determination of the Oligomeric State of SecYEG Protein Secretion Channel Complex Using in Vivo Photo- and Disulfide Cross-linking

Zheng

Blum

Banerjee

et al. 2016

Journal of Biological Chemistry

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“…The substitutions were made by standard recombinant DNA techniques (QuikChange, Stratagene). SecB and SecA were purified as described [14, 22]. 14 C –SecB was purified from a culture radiolabelled by growth in minimal medium (M9, vitamin B 1 , 0.4% glycerol).…”

Section: Methodsmentioning

confidence: 99%

The Basis of Asymmetry in the SecA:SecB Complex

Suo

Hardy

Randall

2015

Journal of Molecular Biology

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During export in Escherichia coli, SecB, a homotetramer, structurally organized as a dimer of dimers, forms a complex with two protomers of SecA, which is the ATPase that provides energy to transfer a precursor polypeptide through the membrane via the SecYEG translocon. There are two areas of contact on SecB that stabilize the SecA:SecB complex: one, the flat sides of the SecB tetramer and the second, the C-terminal thirteen residues of SecB. These contacts within the complex are distributed asymmetrically. Breaking contact between SecA and the sides of SecB results in release of only one protomer of SecA yielding a complex of stoichiometry SecA1:SecB4. This complex mediates export; however, the coupling of ATP hydrolysis to movements of the precursor through the translocon is much less efficient than the coupling by the SecA2:SecB4 complex. Here we used heterotetrameric species of SecB to understand the source of the asymmetry in the contacts and its role in the functioning of the complex. The model of interactions presented suggests a way that binding between SecA and SecB might decrease the affinity of precursor polypeptides for SecB and facilitate the transfer to SecA.

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Stoichiometry of SecYEG in the active translocase of Escherichia coli varies with precursor species

Cited by 40 publications

References 45 publications

Membrane Chaperone SecDF Plays a Role in the Secretion of Listeria monocytogenes Major Virulence Factors

Membrane Chaperone SecDF Plays a Role in the Secretion of Listeria monocytogenes Major Virulence Factors

Determination of the Oligomeric State of SecYEG Protein Secretion Channel Complex Using in Vivo Photo- and Disulfide Cross-linking

The Basis of Asymmetry in the SecA:SecB Complex

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