Sequential Checkpoints Govern Substrate Selection During Cotranslational Protein Targeting

Zhang, Xin; Rashid, Rumana; Wang, Kai; Shan, Shu‐ou

doi:10.1126/science.1186743

Cited by 97 publications

(194 citation statements)

References 29 publications

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“…5, green), which restricts the conformation of the early intermediate and produces a more bimodal pattern of distribution. These changes could potentially provide a mechanism to exert biological regulation (18,19). Nevertheless, much more work will be needed to provide a molecular understanding of the conformational changes brought upon by the cargo and how these changes affect the complex assembly process.…”

Section: Discussionmentioning

confidence: 99%

“…The SRP-SR interaction is profoundly influenced by the cargos of SRP, the ribosome-nascent chain complexes (RNCs), which stabilize the early intermediate over 50-fold and accelerate stable complex assembly over 100-fold (18,19). We speculated that the cargo could actively regulate the conformational dynamics of the early intermediate.…”

Section: Electrostatic Interactions Drive Formation and Stability Of mentioning

confidence: 99%

“…Thus, the cargo restricts the dynamics of the early intermediate to a more limited conformational space, in which the successful selection of complementary structures might be enhanced. This could partly explain how the cargo enhances the kinetics of SRP•SR complex assembly and therefore effects efficient protein targeting (18,19).…”

Section: Electrostatic Interactions Drive Formation and Stability Of mentioning

confidence: 99%

“…To understand the protein assembly pathway, it is crucial that on-pathway intermediates during protein assembly can be isolated. To this end, we chose the interaction between the Signal Recognition Particle (SRP) and the SRP receptor (SR) as a model system.Rapid assembly of a stable SRP•SR complex is required to efficiently deliver cargo proteins to cellular membranes during cotranslational protein targeting, and it is essential for proper protein localization in all cells (18,19). Formation of a stable SRP•SR complex is mediated by specific interactions between their NG domains (comprised of a GTPase, G domain, and a helical N domain) (Fig.…”

mentioning

confidence: 99%

“…Rapid assembly of a stable SRP•SR complex is required to efficiently deliver cargo proteins to cellular membranes during cotranslational protein targeting, and it is essential for proper protein localization in all cells (18,19). Formation of a stable SRP•SR complex is mediated by specific interactions between their NG domains (comprised of a GTPase, G domain, and a helical N domain) (Fig.…”

mentioning

confidence: 99%

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Direct visualization reveals dynamics of a transient intermediate during protein assembly

Zhang

Lam

Mou

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Interactions between proteins underlie numerous biological functions. Theoretical work suggests that protein interactions initiate with formation of transient intermediates that subsequently relax to specific, stable complexes. However, the nature and roles of these transient intermediates have remained elusive. Here, we characterized the global structure, dynamics, and stability of a transient, on-pathway intermediate during complex assembly between the Signal Recognition Particle (SRP) and its receptor. We show that this intermediate has overlapping but distinct interaction interfaces from that of the final complex, and it is stabilized by longrange electrostatic interactions. A wide distribution of conformations is explored by the intermediate; this distribution becomes more restricted in the final complex and is further regulated by the cargo of SRP. These results suggest a funnel-shaped energy landscape for protein interactions, and they provide a framework for understanding the role of transient intermediates in protein assembly and biological regulation.EPR spectroscopy | fluorescence spectroscopy | molecular recognition | protein targeting | GTPases I nteractions between proteins are central to biology and underlie numerous molecular recognition, regulation, and signaling events (1). A challenge in our understanding of protein interactions is to reconcile their fast association kinetics required for biological function (10 6 -10 8 M −1 s −1 ) with the fact that formation of stable protein assemblies often involves extensive short-range, stereospecific interactions that are difficult to accomplish during a single diffusional encounter (2-4). This problem becomes more pronounced in protein interactions that require extensive conformational changes in the interaction partners. Much theoretical work has suggested that assembly of a protein complex initiates with the formation of a transient intermediate held together by solvent cage and long-range electrostatic attractions, followed by relative rotatory diffusions of the binding partners to search for the optimal interaction interface with shape and electrostatic complementarity (4-9). An extreme example of this concept is the "fly-casting mechanism," in which unstructured protein molecules bind targets weakly at a relatively large distance followed by folding at the target site (10-12). In general, formation of transient intermediates reduces the dimension of translational and rotational search and could significantly accelerate protein association.Despite significant progress in theoretical work, direct experimental demonstration of this model has been limited, and the structural and dynamic nature of transient intermediates during protein interactions has remained elusive. Experimental studies of transient intermediates are still at the infant stage, because these intermediates have short lifetimes and are rarely populated at equilibrium. Pioneering NMR studies have revealed the structures of rare conformational states in equilibrium with the predominant ...

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Section: Discussionmentioning

confidence: 99%

Section: Electrostatic Interactions Drive Formation and Stability Of mentioning

confidence: 99%

Section: Electrostatic Interactions Drive Formation and Stability Of mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Direct visualization reveals dynamics of a transient intermediate during protein assembly

Zhang

Lam

Mou

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Implementation of FRET Technologies for Studying the Folding and Conformational Changes in Biological Structures

Robinson

Woolhead

2013

FRET – Förster Resonance Energy Transfer

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A tale of two GTPases in cotranslational protein targeting

2011

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Guanosine triphosphatases (GTPases) comprise a superfamily of proteins that provide molecular switches to regulate numerous cellular processes. The ''GTPase switch'' paradigm, in which a GTPase acts as a bimodal switch that is turned ''on'' and ''off'' by external regulatory factors, has been used to interpret the regulatory mechanism of many GTPases. Recent work on a pair of GTPases in the signal recognition particle (SRP) pathway has revealed a distinct mode of GTPase regulation. Instead of the classical GTPase switch, the two GTPases in the SRP and SRP receptor undergo a series of conformational changes during their dimerization and reciprocal activation. Each conformational rearrangement provides a point at which these GTPases can communicate with and respond to their upstream and downstream biological cues, thus ensuring the spatial and temporal precision of all the molecular events in the SRP pathway. We suggest that the SRP and SRP receptor represent an emerging class of ''multistate'' regulatory GTPases uniquely suited to provide exquisite control over complex cellular pathways that require multiple molecular events to occur in a highly coordinated fashion.

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Sequential Checkpoints Govern Substrate Selection During Cotranslational Protein Targeting

Cited by 97 publications

References 29 publications

Direct visualization reveals dynamics of a transient intermediate during protein assembly

Direct visualization reveals dynamics of a transient intermediate during protein assembly

Implementation of FRET Technologies for Studying the Folding and Conformational Changes in Biological Structures

A tale of two GTPases in cotranslational protein targeting

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