TY - JOUR
T1 - Connecting actin monomers by iso-peptide bond is a toxicity mechanism of the Vibrio cholerae MARTX toxin
AU - Kudryashov, Dmitri S.
AU - Oztug Durer, Zeynep A.
AU - Ytterberg, A. Jimmy
AU - Sawaya, Michael R.
AU - Pashkov, Inna
AU - Prochazkova, Katerina
AU - Yeates, Todd O.
AU - Ogorzalek Loo, Rachel R.
AU - Loo, Joseph A.
AU - Fullner Satchell, Karla J.
AU - Reisler, Emil
PY - 2008/11/25
Y1 - 2008/11/25
N2 - The Gram-negative bacterium Vibrio cholerae is the causative agent of a severe diarrheal disease that afflicts three to five million persons annually, causing up to 200,000 deaths. Nearly all V. cholerae strains produce a large multifunctional-autoprocessing RTX toxin (MARTXVc), which contributes significantly to the pathogenesis of cholera in model systems. The actin cross-linking domain (ACD) of MARTXVc directly catalyzes a covalent cross-linking of monomeric G-actin into oligomeric chains and causes cell rounding, but the nature of the cross-linked bond and the mechanism of the actin cytoskeleton disruption remained elusive. To elucidate the mechanism of ACD action and effect on actin, we identified the covalent cross-link bond between actin protomers using limited proteolysis, X-ray crystallography, and mass spectrometry. We report here that ACD catalyzes the formation of an intermolecular iso-peptide bond between residues E270 and K50 located in the hydrophobic and the DNaseI-binding loops of actin, respectively. Mutagenesis studies confirm that no other residues on actin can be cross-linked by ACD both in vitro and in vivo. This cross-linking locks actin protomers into an orientation different from that of F-actin, resulting in strong inhibition of actin polymerization. This report describes a microbial toxin mechanism acting via iso-peptide bond cross-linking between host proteins and is, to the best of our knowledge, the only known example of a peptide linkage between nonterminal glutamate and lysine side chains.
AB - The Gram-negative bacterium Vibrio cholerae is the causative agent of a severe diarrheal disease that afflicts three to five million persons annually, causing up to 200,000 deaths. Nearly all V. cholerae strains produce a large multifunctional-autoprocessing RTX toxin (MARTXVc), which contributes significantly to the pathogenesis of cholera in model systems. The actin cross-linking domain (ACD) of MARTXVc directly catalyzes a covalent cross-linking of monomeric G-actin into oligomeric chains and causes cell rounding, but the nature of the cross-linked bond and the mechanism of the actin cytoskeleton disruption remained elusive. To elucidate the mechanism of ACD action and effect on actin, we identified the covalent cross-link bond between actin protomers using limited proteolysis, X-ray crystallography, and mass spectrometry. We report here that ACD catalyzes the formation of an intermolecular iso-peptide bond between residues E270 and K50 located in the hydrophobic and the DNaseI-binding loops of actin, respectively. Mutagenesis studies confirm that no other residues on actin can be cross-linked by ACD both in vitro and in vivo. This cross-linking locks actin protomers into an orientation different from that of F-actin, resulting in strong inhibition of actin polymerization. This report describes a microbial toxin mechanism acting via iso-peptide bond cross-linking between host proteins and is, to the best of our knowledge, the only known example of a peptide linkage between nonterminal glutamate and lysine side chains.
KW - Cross-linking
KW - Mass spectrometry
KW - X-ray crystallography
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U2 - 10.1073/pnas.0808082105
DO - 10.1073/pnas.0808082105
M3 - Article
C2 - 19015515
AN - SCOPUS:57449094208
VL - 105
SP - 18537
EP - 18542
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 47
ER -