The cytotoxic effect of diphtheria toxin on the actin cytoskeleton


Varol B., Bektas M., Nurten R., Bermek E.

CELLULAR & MOLECULAR BIOLOGY LETTERS, cilt.17, sa.1, ss.49-61, 2012 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 17 Sayı: 1
  • Basım Tarihi: 2012
  • Doi Numarası: 10.2478/s11658-011-0036-6
  • Dergi Adı: CELLULAR & MOLECULAR BIOLOGY LETTERS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.49-61
  • Anahtar Kelimeler: ADP-ribosylation, Diphtheria toxin, Eukaryotic elongation factor-2, F-actin, Fragment A, ELONGATION-FACTOR 2, ADP-RIBOSYLATION, EUKARYOTIC ELONGATION-FACTOR-2, TRANSLOCATION, FRAGMENT, ASSOCIATION, INVOLVEMENT, MACHINERY, PROTEINS, BINDING
  • İstanbul Üniversitesi Adresli: Evet

Özet

Diphtheria toxin (DT) and its N-terminal fragment A (FA) catalyse the transfer of the ADP-ribose moiety of nicotinamide adenine dinucleotide (NAD) into a covalent linkage with eukaryotic elongation factor 2 (eEF2). DT-induced cytotoxicity is versatile, and it includes DNA cleavage and the depolymerisation of actin filaments. The inhibition of the ADP-ribosyltransferase (ADPrT) activity of FA did not affect the deoxyribonuclease activity of FA or its interaction with actin. The toxin entry rate into cells (HUVEC) was determined by measuring the ADP-ribosyltransferase activity. DT uptake was nearly 80% after 30 min. The efficiency was determined as K-m = 2.2 nM; V-max = 0.25 pmol.min(-1). The nuclease activity was tested with hyperchromicity experiments, and it was concluded that G-actin has an inhibitory effect on DT nuclease activity. In thepresence of DT and mutant of diphtheria toxin (CRM197), F-actin depolymerisation was determined with gel filtration, WB and fluorescence techniques. In the presence of DT and CRM197, 60-65% F-actin depolymerisation was observed. An in vitro FA-actin interaction and F-actin depolymerisation were reported in our previous paper. The present study thus confirms the depolymerisation of actin cytoskeleton in vivo.