1mi8
From Proteopedia
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'''2.0 Angstrom crystal structure of a DnaB intein from Synechocystis sp. PCC 6803''' | '''2.0 Angstrom crystal structure of a DnaB intein from Synechocystis sp. PCC 6803''' | ||
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[[Category: Rao, Z.]] | [[Category: Rao, Z.]] | ||
[[Category: Xu, M.]] | [[Category: Xu, M.]] | ||
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| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 01:05:56 2008'' | |
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Revision as of 22:05, 2 May 2008
2.0 Angstrom crystal structure of a DnaB intein from Synechocystis sp. PCC 6803
Overview
We have determined the crystal structure of a 154-residue intein derived from the dnaB gene of Synechocystis sp. strain PCC6803 and refined it to a 2.0-A resolution. The x-ray structure suggests that this intein possesses two catalytic sites that appear to be separately responsible for splicing and cleavage of the N- and C-terminal scissile bonds. The conserved intein block F residues are the important components of a catalytic site for side chain cyclization of the last intein residue, Asn-154. The data suggest that the imidazole ring of His-143 is involved in the activation of the side chain Ndelta atom of Asn-154, leading to a nucleophilic attack on the carbonyl carbon of Asn-154. Substitution of His-143 with Ala or Gln resulted in the inhibition of C-terminal cleavage. His-153, Asp-136, and a water molecule appear to constitute an oxyanion binding site by contacting the carbonyl oxygen of Asn-154 to stabilize the transition state. The structure and mutagenesis data also support that the close contact between the hydroxyl groups of Thr-138 and Ser-155, whose side chain participates in an S --> O acyl shift, plays an important role in the nucleophile orientation. Our structural modeling suggests that this catalytic module is conserved in the C-terminal subdomains of inteins from diverse organisms.
About this Structure
1MI8 is a Single protein structure of sequence from Synechocystis sp.. Full crystallographic information is available from OCA.
Reference
Crystal structure of a mini-intein reveals a conserved catalytic module involved in side chain cyclization of asparagine during protein splicing., Ding Y, Xu MQ, Ghosh I, Chen X, Ferrandon S, Lesage G, Rao Z, J Biol Chem. 2003 Oct 3;278(40):39133-42. Epub 2003 Jul 23. PMID:12878593 Page seeded by OCA on Sat May 3 01:05:56 2008
