Direct visualization reveals dynamics of a transient intermediate during protein assembly

Xin Zhang, Vinh Q. Lam, Yun Mou, Tetsunari Kimura, Jaeyoon Chung, Sowmya Chandrasekar, Jay R. Winkler, Stephen L. Mayo, Shu Ou Shan

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


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 long-range 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.

Original languageEnglish (US)
Pages (from-to)6450-6455
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Apr 19 2011

All Science Journal Classification (ASJC) codes

  • General


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