Interaction of the phosphorylated DNA-binding domain in nuclear receptor CAR with its ligand-binding domain regulates CAR activation.

The nuclear protein constitutive active/androstane receptor (CAR or NR1I3) regulates several liver functions such as drug and energy metabolism and cell growth or death, which are often involved in the development of diseases such as diabetes and hepatocellular carcinoma. CAR undergoes a conversion from inactive homodimers to active heterodimers with retinoid X receptor α (RXRα), and phosphorylation of the DNA-binding domain (DBD) at Thr-38 in CAR regulates this conversion. Here, we uncovered the molecular mechanism by which this phosphorylation regulates the intramolecular interaction between CAR's DBD and ligand-binding domain (LBD), enabling the homodimer-heterodimer conversion.

Reversible Association of the Hemagglutinin Subcomplex, HA-33/HA-17 Trimer, with the Botulinum Toxin Complex.

Botulinum neurotoxin (BoNT) associates with nontoxic proteins, either a nontoxic nonhemagglutinin (NTNHA) or the complex of NTNHA and hemagglutinin (HA), to form M- or L-toxin complexes (TCs). Single BoNT and NTNHA molecules are associated and form M-TC. A trimer of the 70-kDa HA protein (HA-70) attaches to the M-TC to form M-TC/HA-70.

Isolation of botulinolysin, a thiol-activated hemolysin, from serotype D Clostridium botulinum: A species-specific gene duplication in Clostridia.

Botulinolysin (BLY) is a toxin produced by Clostridium botulinum that belongs to a group of thiol-activated hemolysins. In this study, a protein exhibiting hemolytic activity was purified from the culture supernatant of C. botulinum serotype D strain 4947.

Phenobarbital indirectly activates the constitutive active androstane receptor (CAR) by inhibition of epidermal growth factor receptor signaling.

Phenobarbital is a central nervous system depressant that also indirectly activates nuclear receptor constitutive active androstane receptor (CAR), which promotes drug and energy metabolism, as well as cell growth (and death), in the liver. We found that phenobarbital activated CAR by inhibiting epidermal growth factor receptor (EGFR) signaling. Phenobarbital bound to EGFR and potently inhibited the binding of EGF, which prevented the activation of EGFR.

Dephosphorylation of threonine 38 is required for nuclear translocation and activation of human xenobiotic receptor CAR (NR1I3).

Upon activation by therapeutics, the nuclear xenobiotic/ constitutive active/androstane receptor (CAR) regulates various liver functions ranging from drug metabolism and excretion to energy metabolism. CAR can also be a risk factor for developing liver diseases such as hepatocellular carcinoma. Here we have characterized the conserved threonine 38 of human CAR as the primary residue that regulates nuclear translocation and activation of CAR.

Quantitative detection of gene expression and toxin complex produced by Clostridium botulinum serotype D strain 4947.

Botulinum toxin is produced by Clostridium botulinum as a large toxin complex (L-TC) non-covalently assembled with a neurotoxin (NT), a non-toxic non-hemagglutinin (NTNHA) and hemagglutinin subcomponents (HA-70, HA-33, and HA-17). In this study, the gene expressions of five individual L-TC components were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in C. botulinum serotype D strain 4947 (D-4947) during cell growth.

Four molecules of the 33 kDa haemagglutinin component of the Clostridium botulinum serotype C and D toxin complexes are required to aggregate erythrocytes.

Normally, large-sized botulinum toxin complexes (L-TC) of serotype C and D are composed of a single neurotoxin, a single non-toxic non-haemagglutinin, two HA-70 molecules, four HA-33 molecules and four HA-17 molecules that assemble to form a 650 kDa L-TC. The 540 and 610 kDa TC species (designated here as L-TC2 and L-TC3, respectively) were purified in addition to the 650 kDa L-TC from the culture supernatants of serotype D strains (D-4947 and D-CB16) and serotype C strains (C-6814 and C-Yoichi). The 650 kDa L-TC from D-4947, D-CB16 and C-6814 showed haemagglutination and erythrocyte-binding activity, but their L-TC2 and L-TC3 species had only binding activity.

Characterization of the interaction between subunits of the botulinum toxin complex produced by serotype D through tryptic susceptibility of the isolated components and complex forms.

The 650 kDa large toxin complex (L-TC) produced by Clostridium botulinum serotype D strain 4947 (D-4947) has a subunit structure composed of unnicked components, i.e. neurotoxin (NT), non-toxic non-haemagglutinin (NTNHA) and three haemagglutinin subcomponents (HA-70, HA-33 and HA-17).

Characterization of toxin complex produced by a unique strain of Clostridium botulinum serotype D 4947.

A unique strain of Clostridium botulinum, serotype D 4947 (D-4947), produces a considerable amount of a 650 kDa toxin complex (L-TC) and a small amount of a 280 kDa M-TC, a 540 kDa TC, and a 610 kDa TC. The complexes are composed of only un-nicked components, including neurotoxin (NT), nontoxic nonhemagglutinin (NTNHA) and hemagglutinin subcomponents (HA-70, HA-33 and HA-17). Unlike other NTs from all serotype strains, separation of D-4947 NT from L-TC, except for M-TC, during chromatography required highly alkaline conditions around pH 8.

Complete subunit structure of the Clostridium botulinum type D toxin complex via intermediate assembly with nontoxic components.

Clostridium botulinum serotype D strains usually produce two types of stable toxin complex (TC), namely, the 300 kDa M (M-TC) and the 660 kDa L (L-TC) toxin complexes. We previously proposed assembly pathways for both TCs [Kouguchi, H., et al.

Molecular characterization of GroES and GroEL homologues from Clostridium botulinum.

We report novel findings of significant amounts of 60- and 10-kDa proteins on SDS-PAGE in a culture supernatant of the Clostridium botulinum type D strain 4947 (D-4947). The N-terminal amino acid sequences of the purified proteins were closely related to those of other bacterial GroEL and GroES proteins, and both positively cross-reacted with Escherichia coli GroEL and GroES antibodies. Native GroEL homologue as an oligomeric complex is a weak ATPase whose activity is inhibited by the presence of GroES homologue.