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Structure and solution dynamics of CdtB, the biologically active subunit of Cytolethal Distending Toxin
Author(s) -
Hontz Jill S.,
VillarLecumberri Maria T.,
Potter Belinda M.,
Laity John H.,
Yoder Marilyn D.,
Dreyfus Lawrence A.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a490
Subject(s) - cytolethal distending toxin , toxin , protein subunit , chemistry , biological activity , microbial toxins , biochemistry , gene , in vitro
Cytolethal Distending Toxin is a DNA‐damaging bacterial toxin that induces cell cycle arrest in eukaryotic cells. Following cell‐surface binding and cellular entry, CdtB, a type I DNase homolog, traffics to the nucleus and cleaves chromosomal DNA. Here we combine X‐ray crystallography and multidimensional NMR to examine the molecular structure and solution dynamics of the free Escherichia coli CdtB (EcCdtB) subunit. Comparison of the EcCdtB crystal structure and NMR solution state structure and dynamics data reveals distinct differences in two key regions of CdtB. Most notably, residues 186‐210 (region1) adopt a well‐defined tertiary structure in the crystallographic model, in contrast to the solution state that has “random coil” structural and dynamics characteristics. CdtB residues R235‐I239 (region 2) are also highly mobile in solution. Regions 1 and 2 are either flanked by or encompass two bipartite nuclear localization sequences (NLS), respectively. Region 2 also makes contacts in the CdtB interface with CdtA and CdtC subunits as defined by the holotoxin structure of the Haemophilus ducreyi CDT. With the exception of regions 1 and 2, EcCdtB and the CdtB component of H. ducreyi holotoxin have very similar structures (Cα r.m.s.d. of 0.98 Å). Overall, these comparisons of solution and crystal forms of CdtB provide new insights into holotoxin assembly and CdtB nuclear localization.