title: Evolution and mechanism from structures of an ADP-ribosylating toxin and NAD complex.
abstract: A member of the Bacillus-produced vegetative insecticidal proteins (VIPs) possesses high specificity against the major insect pest, corn rootworms, and belongs to a class of binary toxins and regulators of biological pathways distinct from classical A-B toxins. The 1.5 A resolution crystal structure of the enzymatic ADP-ribosyltransferase component, VIP2, from Bacillus cereus reveals structurally homologous N- and C-terminal alpha/beta domains likely representing the entire class of binary toxins and implying evolutionary relationships between families of ADP-ribosylating toxins. The crystal structure of the kinetically trapped VIP2-NAD complex identifies the NAD binding cleft within the C-terminal enzymatic domain and provides a structural basis for understanding the targeting and catalysis of the medically and environmentally important binary toxins. These structures furthermore provide specific experimental results to help resolve paradoxes regarding the specific mechanism of ADP-ribosylation of actin by implicating ground state destabilization and nicotinamide product sequestration as the major driving forces for catalysis.
authors.affiliation: Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: S
authors.initials: S
authors.lastname: Han
authors.forename: J A
authors.initials: JA
authors.lastname: Craig
authors.forename: C D
authors.initials: CD
authors.lastname: Putnam
authors.forename: N B
authors.initials: NB
authors.lastname: Carozzi
authors.forename: J A
authors.initials: JA
authors.lastname: Tainer
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D001409:Bacillus cereus / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D003460:Crystallization; D018360:Crystallography, X-Ray; D019143:Evolution, Molecular; D006860:Hydrogen Bonding; D007306:Insecticides / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000737:chemistry / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D007306:Insecticides; D010710:Phosphates; C121896:VIP2 protein, Bacillus cereus; D009243:NAD; D011065:Poly(ADP-ribose) Polymerases