Journal article
Variation of loop sequence alters stability of cytolethal distending toxin (CDT): crystal structure of CDT from Actinobacillus actinomycetemcomitans
Protein science, Vol.15(2), pp.362-372
02/2006
DOI: 10.1110/ps.051790506
PMCID: PMC2242449
PMID: 16434747
Abstract
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.
Details
- Title: Subtitle
- Variation of loop sequence alters stability of cytolethal distending toxin (CDT): crystal structure of CDT from Actinobacillus actinomycetemcomitans
- Creators
- Taro Yamada - Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045-7534, USAJunichi KomotoKeitarou SaikiKiyoshi KonishiFusao Takusagawa
- Resource Type
- Journal article
- Publication Details
- Protein science, Vol.15(2), pp.362-372
- Publisher
- United States
- DOI
- 10.1110/ps.051790506
- PMID
- 16434747
- PMCID
- PMC2242449
- ISSN
- 0961-8368
- eISSN
- 1469-896X
- Grant note
- R01 GM037233 / NIGMS NIH HHS GM37233 / NIGMS NIH HHS P20 RR-17708 / NCRR NIH HHS P20 RR017708 / NCRR NIH HHS
- Language
- English
- Date published
- 02/2006
- Academic Unit
- Neurology
- Record Identifier
- 9984020891302771
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