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X-ray structure of translation initiation factor eIF2gamma: implications for tRNA and eIF2alpha binding
Antonina Roll-Mecak1, Pankaj Alone, Chune Cao
1Laboratories of Molecular Biophysics, The Rockefeller University, New York, New York 10021, USA.
The Journal of Biological Chemistry
|December 23, 2003
Summary
The structure of the translation initiation factor eIF2 gamma-subunit was solved, revealing a zinc ribbon motif. This finding offers new insights into how eIF2 binds essential components for protein synthesis.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Translation initiation is a critical, rate-limiting step in protein synthesis.
- The eukaryotic translation initiation factor 2 (eIF2) is a GTPase essential for delivering initiator tRNA to the ribosome.
- Understanding eIF2 structure and function is key to deciphering translation regulation.
Purpose of the Study:
- To determine the high-resolution X-ray structure of the gamma-subunit of eIF2.
- To elucidate the structural basis for eIF2 interactions with its binding partners.
- To gain insights into the assembly mechanism of the eIF2 ternary complex.
Main Methods:
- X-ray crystallography to determine the 2.4-A resolution structure of eIF2 gamma-subunit.
- Structure-based site-directed mutagenesis.
- Biochemical and genetic analyses.
Main Results:
- The structure of eIF2 gamma-subunit was determined, showing resemblance to EF1A.GTP.
- An unusual zinc ribbon motif was identified in the G domain of eIF2 gamma-subunit.
- Two distinct surface regions responsible for binding the alpha-subunit and Met-tRNA(i)(Met) were identified.
Conclusions:
- The determined structure provides a detailed molecular model of eIF2 gamma-subunit.
- The identified zinc ribbon motif represents a novel feature in GTPases.
- These findings advance our understanding of eIF2 function in translation initiation and ternary complex formation.