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PDBsum entry 4ls4
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References listed in PDB file
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Key reference
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Title
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Crystal structure of apo and copper bound hp0894 toxin from helicobacter pylori 26695 and insight into mrnase activity.
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Authors
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C.Pathak,
H.Im,
Y.J.Yang,
H.J.Yoon,
H.M.Kim,
A.R.Kwon,
B.J.Lee.
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Ref.
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Biochim Biophys Acta, 2013,
1834,
2579-2590.
[DOI no: ]
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PubMed id
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Abstract
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The toxin-antitoxin (TA) systems widely spread among bacteria and archaea are
important for antibiotic resistance and microorganism virulence. The bacterial
kingdom uses TA systems to adjust the global level of gene expression and
translation through RNA degradation. In Helicobacter pylori, only two TA systems
are known thus far. Our previous studies showed that HP0894-HP0895 acts as a TA
system and that HP0894 exhibits intrinsic RNase activity. However, the precise
molecular basis for interaction with substrate or antitoxin and the mechanism of
mRNA cleavage remain unclear. Therefore, in an attempt to shed some light on the
mechanism behind the TA system of HP0894-HP0895, here we present the crystal
structures of apo- and metal-bound H. pylori 0894 at 1.28Å and 1.89Å,
respectively. Through the combined approach of structural analysis and
structural homology search, the amino acids involved in mRNase active site were
monitored and the reorientations of different residues were discussed in detail.
In the mRNase active site of HP0894 toxin, His84 acts as a catalytic residue and
reorients itself to exhibit this type of activity, acting as a general acid in
an acid-base catalysis reaction, while His47 and His60 stabilize the transition
state. Lys52, Glu58, Asp64 and Arg80 have phosphate binding and specific
sequence recognition. Glu58 also acts as a general base, and substrate
reorientation is caused by Phe88. Based on experimental findings, a model for
antitoxin binding could be suggested.
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