Structural organization of the human PON1 gene

Area of Science:

• Biochemistry
• Genetics
• Toxicology

Background:

• Serum paraoxonase/arylesterase (PON) is an HDL-associated enzyme with esterase activity.
• PON hydrolyzes organophosphate insecticide metabolites and nerve agents, and degrades oxidized phospholipids.
• Individual PON serum levels vary due to activity polymorphism and protein level differences, impacting toxin sensitivity.

Purpose of the Study:

• To characterize the human PON gene, including its coding and flanking sequences.
• To identify genetic variations within the PON gene.
• To provide a foundation for understanding PON's role in detoxification and disease.

Main Methods:

• Contig mapping of a 28-kb genomic region containing the PON gene.
• Sequencing of the 5' flanking region, coding exons, and 3' flanking region.
• Identification of gene structure, including exon-intron boundaries and a polymorphic marker.

Main Results:

• Characterization of a 28-kb contig of the PON gene, including 300 bp of 5' sequence, the full coding region, and 2 kb of 3' sequence.
• The PON protein-coding region is encoded by nine exons.
• A polymorphic CA repeat was identified in intron 4, indicating genetic variability.

Conclusions:

• The characterized PON gene structure provides insights into its regulation and potential for polymorphism.
• Understanding PON gene variations is crucial for assessing individual susceptibility to organophosphate toxicity.
• The arg192 PON isoform is linked to coronary artery disease risk, highlighting PON's broader physiological relevance.