title: Tyrosine 331 and phenylalanine 334 in Clostridium perfringens alpha-toxin are essential for cytotoxic activity.
abstract: Differences in the biological properties of the Clostridium perfringens phospholipase C (alpha-toxin) and the C. bifermentans phospholipase C (Cbp) have been attributed to differences in their carboxy-terminal domains. Three residues in the carboxy-terminal domain of alpha-toxin, which have been proposed to play a role in membrane recognition (D269, Y331 and F334), are not conserved in Cbp (Y, L and I respectively). We have characterised D269Y, Y331L and F334I variant forms of alpha-toxin. Variant D269Y had reduced phospholipase C activity towards aggregated egg yolk phospholipid but increased haemolytic and cytotoxic activity. Variants Y331L and F334I showed a reduction in phospholipase C, haemolytic and cytotoxic activities indicating that these substitutions contribute to the reduced haemolytic and cytotoxic activity of Cbp.
authors.affiliation: Defense Evaluation Research Agency, CBD Porton Down, Salisbury, UK.
authors.forename: M
authors.initials: M
authors.lastname: Jepson
authors.forename: H L
authors.initials: HL
authors.lastname: Bullifent
authors.forename: D
authors.initials: D
authors.lastname: Crane
authors.forename: M
authors.initials: M
authors.lastname: Flores-Diaz
authors.forename: A
authors.initials: A
authors.lastname: Alape-Giron
authors.forename: P
authors.initials: P
authors.lastname: Jayasekeera
authors.forename: B
authors.initials: B
authors.lastname: Lingard
authors.forename: D
authors.initials: D
authors.lastname: Moss
authors.forename: R W
authors.initials: RW
authors.lastname: Titball
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000502:physiology; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D007532:Isoleucine / Q000235:genetics; D007930:Leucine / Q000235:genetics; D008081:Liposomes / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000235:genetics / Q000502:physiology; D010743:Phospholipids / Q000378:metabolism; D010738:Type C Phospholipases / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D014443:Tyrosine / Q000235:genetics / Q000502:physiology
chemical_list: D001427:Bacterial Toxins; D002135:Calcium-Binding Proteins; D008081:Liposomes; D010743:Phospholipids; D007532:Isoleucine; D001224:Aspartic Acid; D014443:Tyrosine; D010649:Phenylalanine; D010738:Type C Phospholipases; C040649:alpha toxin, Clostridium perfringens; D007930:Leucine