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Network models reveal stability and structural rearrangement of signal recognition particle

Shan Chang1, Hong-qiu He, Jian-ping Hu

  • 1College of Informatics, South China Agricultural University, Guangzhou, 510642, China. schang@scau.edu.cn

Journal of Biomolecular Structure & Dynamics
|June 19, 2012
PubMed

Insights

Signal recognition particle (SRP) and its receptor (SR) interactions stabilize protein targeting. Molecular dynamics simulations reveal domain movements facilitating SRP structural changes during protein translocation.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biophysics

Background:

  • The signal recognition particle (SRP) and its receptor (SR) complex are crucial for targeting membrane and secretory proteins during translation.
  • In Escherichia coli, SRP consists of the Ffh protein and 4.5S SRP RNA, with Ffh featuring methionine-rich (M), N-terminal (N), and GTPase (G) domains, often grouped as the NG domain.

Purpose of the Study:

  • To investigate the complex structure and dynamics of the SRP-SR complex using computational models.
  • To elucidate the functional movements of the Ffh protein within the SRP complex during cotranslational protein targeting.

Main Methods:

  • Gaussian Network Model (GNM) for analyzing structural stability and fluctuations.
  • Anisotropic Network Model (ANM) and cross-correlation analysis to determine the directions of domain movements.

Main Results:

  • Intermolecular interactions between SRP and SR significantly reduce fluctuations in the NG domains.
  • Large-scale structural rearrangements occur during the protein targeting cycle.
  • The NG domain of Ffh rotates clockwise around the GM linker, while the M domain moves in the opposite direction.

Conclusions:

  • The identified functional movements of the Ffh domains facilitate the structural transitions of SRP between its free and sequence-bound states.
  • Coarse-grained modeling approaches like GNM and ANM offer a rapid and generalizable method for studying protein assembly and supramolecular systems.

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