2f2f
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(New page: 200px<br /><applet load="2f2f" size="450" color="white" frame="true" align="right" spinBox="true" caption="2f2f, resolution 2.4Å" /> '''Crystal structure of ...)
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Revision as of 08:11, 21 November 2007
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Crystal structure of cytolethal distending toxin (CDT) from Actinobacillus actinomycetemcomitans
Overview
Cytolethal distending toxin (CDT) secreted by Actinobacillus, actinomycetemcomitans induces cell cycle arrest of cultured cells in the, G2 phase. The crystal structure of the natural form of A., actinomycetemcomitans DCT (aCDT) has been determined at 2.4 A resolution., aCDT is a heterotrimer consisting of the three subunits, aCdtA, aCdtB, and, aCdtC. Two crystallographically independent aCDTs form a dimer through, interactions of the aCdtB subunits. The primary structure of aCDT has, 94.3% identity with that of Haemophilus ducreyi CDT (hCDT), and the, structure of aCDT is quite similar to that of hCDT reconstituted from the, three subunits determined recently. However, the molecular packings in the, crystal structures of aCDT and hCDT are quite different. A careful, analysis of molecular packing suggests that variation of the amino acid, residues in a nonconserved loop (181TSSPSSPERRGY192 of aCdtB and, 181NSSSSPPERRVY192 of hCdtB) is responsible for the different, oligomerization of very similar CDTs. The loop of aCdtB has a conformation, to form a dimer, while the loop conformation of hCdtB prevents hCDT from, forming a dimer. Although dimerization of aCDT does not affect toxic, activity, it changes the stability of protein. aCDT rapidly aggregates and, loses toxic activity in the absence of sucrose in a buffered solution, while hCDT is stable and retains toxic activity. Another analysis of, crystal structures of aCDT and hCDT suggests that the receptor contact, area is in the deep groove between CdtA and CdtC, and the characteristic, "aromatic patch" on CdtA.
About this Structure
2F2F is a Protein complex structure of sequences from Aggregatibacter actinomycetemcomitans. Full crystallographic information is available from OCA.
Reference
Variation of loop sequence alters stability of cytolethal distending toxin (CDT): crystal structure of CDT from Actinobacillus actinomycetemcomitans., Yamada T, Komoto J, Saiki K, Konishi K, Takusagawa F, Protein Sci. 2006 Feb;15(2):362-72. PMID:16434747
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