1khi: Difference between revisions

[[Image:1khi.jpg|left|200px]]<br /><applet load="1khi" size="350" color="white" frame="true" align="right" spinBox="true"  

The Woronin body is a dense-core vesicle specific to filamentous ascomycetes (Euascomycetes), where it functions to seal the septal pore in response to cellular damage. The HEX-1 protein self-assembles to form this solid core of the vesicle. Here, we solve the crystal structure of HEX-1 at 1.8 A, which provides the structural basis of its self-assembly. The structure reveals the existence of three intermolecular interfaces that promote the formation of a three-dimensional protein lattice. Consistent with these data, self-assembly is disrupted by mutations in intermolecular contact residues and expression of an assembly-defective HEX-1 mutant results in the production of aberrant Woronin bodies, which possess a soluble noncrystalline core. This mutant also fails to complement a hex-1 deletion in Neurospora crassa, demonstrating that the HEX-1 protein lattice is required for Woronin body function. Although both the sequence and the tertiary structure of HEX-1 are similar to those of eukaryotic initiation factor 5A (eIF-5A), the amino acids required for HEX-1 self-assembly and peroxisomal targeting are absent in eIF-5A. Thus, we propose that a new function has evolved following duplication of an ancestral eIF-5A gene and that this may define an important step in fungal evolution.

1KHI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Neurospora_crassa Neurospora crassa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KHI OCA].  

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