The EBPI 777/2205 has a hisD3052 mutation, a -1 frameshift mutation which affects the reading frame of a repetitive -C-G-C-G-C-G-C-G- sequence on the hisD gene.  The hisD gene encodes histidinol dehydrogenase, an enzyme involved in the terminal step of histidine biosynthesis. EBPI 777 also contains a bicistronic protein expression vector, pP4501A2-red, which contains human cytochrome P450 1A2 and human NADPH-P450 reductase cDNA.  The recombinant expression of these two proteins helps in the bioactivation of drug and foreign compounds into DNA-reactive mutagens.  The co-expression of NADPH-P450 reductase with P450 1A2 increases the bioactivation level of the system. This system acts as an in vitro mimic involving the uptake and breakdown of xenobiotic compounds by a mammal and its liver enzymes, resulting in the generation of mutagenic products inside the living system.

Ames Express bacterial strains 777/59/17 expression of P450 1A2 and NADPH-P450 reductase

TA1538          EBP777          hisD3052                -1 Frameshift               Recombinant Expression of P450 1A2

TA98              EBP59            hisD3052               -1 Frameshift                Recombinant Expression of P450 1A2 

TA100            EBP17            hisG46              Base-Pair Substitution      Recombinant Expression of P450 1A2

Another advantage with the recombinant P450 1A2 and NADPH-P450 reductase expression system is that the reactive metabolites will be generated inside the cell rather than outside the cell, as is seen with the S9 rat liver mix.  As a result, this mode of bioactivation will allow short half-life reactive mutagens enough time to reach DNA sites allowing for an increase in sensitivity to mutagenesis.

The recombinant P450 protein also serves as a cost effective and animal friendly alternative to the S9 rat liver extract mix which is the current bioactivation standard.

Metabolically Activates Carcinogens:

MeIQ, Hetrocyclic amine, Alfatoxin B1

2-Amino-1-methyle-6-phenylimidazo (4,5-b) pyridine (PhIP)

3-Methyl-2-methylaminoimidazo (4,5-f)quinoline (IQ)

Polycyclic Aromatic Hydrocarbons (PAH)

The Ames Express^TM System:

This system acts as an in vitro mimic involving the uptake and breakdown of xenobiotic compounds by a mammal and its liver enzymes, resulting in the generation of mutagenic products inside the living system. The recombinant P450 1A2 protein also serves as a cost effective and animal friendly alternative to the S9 rat liver extract mix which is the current bio-activation standard . Like EBPI`s GST expressing strains, the recombinant P450 1A2 reductase expression system is that the reactive metabolites will be generated inside the cell rather than outside the cell.  As a result, this mode of bioactivation will allow short half-life reactive mutagens enough time to reach DNA sites allowing for an increase in sensitivity to mutagenesis.

P450 1A2 is a Phase 1 enzyme found primarily in the hepatic tissue and is responsible for metabolizing polyaromatic hydrocarbons (PAHs), aromatic amines and nitro aromatics. It performs a variety of chemical reactions on several different xenobiotic classes and is a key contributor to the mechanistic mutagenicity of well known carcinogens like benzo(a)pyrene (B[a]P), PhIP and 4-aminobiphenyl.

Click Here for information on  GST T1-1 Ames Express Bacterial Strains.

Potential Applciations:

• Testing of pharmaceuticals for mutagenic activity

• Testing of industrial effluents for presence of possible mutagenic compounds

• Screening of municipal discharges for possible routine presence or spills of mutagenic compounds

• Screening of surface and/or groundwater for mutagenic residues

• Screening of potable water supplies for the presence of chemicals with mutagenic potential

• Screening of water soluble air pollutants for mutagenic agents

• Evaluation of pure or complexed raw mixtures for potential mutagenicity

• A convenient and easy to use teaching tool for university and college laboratories