1yz7

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spinqualitylabelsall models 1yz7, resolution 2.26Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of a C-terminal segment of the alpha subunit of aIF2 from Pyrococcus abyssi

Overview

Eukaryotic and archaeal initiation factor 2 (e- and aIF2, respectively), are heterotrimeric proteins (alphabetagamma) supplying the small subunit, of the ribosome with methionylated initiator tRNA. The gamma subunit forms, the core of the heterotrimer. It resembles elongation factor EF1-A and, ensures interaction with Met-tRNA(i)(Met). In the presence of the alpha, subunit, which is composed of three domains, the gamma subunit expresses, full tRNA binding capacity. This study reports the crystallographic, structure of the intact aIF2alpha subunit from the archaeon Pyrococcus, abyssi and that of a derived C-terminal fragment containing domains 2 and, 3. The obtained structures are compared with those of N-terminal domains 1, and 2 of yeast and human eIF2alpha and with the recently determined NMR, structure of human eIF2alpha. We show that the three-domain organization, in the alpha subunit is conserved in archaea and eukarya. Domains 1 and 2, form a rigid body linked to a mobile third domain. Sequence comparisons, establish that the most conserved regions in the aIF2alpha polypeptide lie, at opposite sides of the protein, within domain 1 and domain 3, respectively. These two domains are known to exhibit RNA binding, capacities. We propose that domain 3, which is known to glue the alpha, subunit onto the gamma subunit, participates in Met-tRNA(i)(Met) binding, while domain 1 recognizes either rRNA or mRNA on the ribosome. Thereby, the observed structural mobility within the e- and aIF2alpha molecules, would be an integral part of the biological function of this subunit in, the heterotrimeric e- and aIF2alphabetagamma factors.

About this Structure

1YZ7 is a Single protein structure of sequence from Pyrococcus abyssi. Full crystallographic information is available from OCA.

Reference

Structure-function relationships of the intact aIF2alpha subunit from the archaeon Pyrococcus abyssi., Yatime L, Schmitt E, Blanquet S, Mechulam Y, Biochemistry. 2005 Jun 21;44(24):8749-56. PMID:15952781

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