Sequence Analysis and Homology Modeling Suggest That Primary Congenital Glaucoma on 2p21 Results from Mutations Disrupting Either the Hinge Region or the Conserved Core Structures of Cytochrome P4501B1

Abstract

We recently reported three truncating mutations of the cytochrome P4501B1 gene (CYP1B1) in five families with primary congenital glaucoma (PCG) linked to the GLC3A locus on chromosome 2p21. This could be the first direct evidence supporting the hypothesis that members of the cytochrome P450 superfamily may control the processes of growth and differentiation. We present a comprehensive sequence analysis of the translated regions of the CYP1B1 gene in 22 PCG families and 100 randomly selected normal individuals. Sixteen mutations and six polymorphisms were identified, illustrating an extensive allelic heterogeneity. The positions affected by these changes were evaluated by building a three-dimensional homology model of the conserved C-terminal half of CYP1B1. These mutations may interfere with heme incorporation, by affecting the hinge region and/or the conserved core structures (CCS) that determine the proper folding and heme-binding ability of P450 molecules. In contrast, all polymorphic sites were poorly conserved and located outside the CCS. Northern hybridization analysis showed strong expression of CYP1B1 in the anterior uveal tract, which is involved in secretion of the aqueous humor and in regulation of outflow facility, processes that could contribute to the elevated intraocular pressure characteristic of PCG.

Novel cytochrome P450 1B1 (CYP1B1) mutations in patients with primary congenital glaucoma in France

“…1). The previously described polymorphisms (Stoilov et al, 1997;Bejjani et al, 1998;Stoilov et al, 1998) were observed, including: g.3793T>C (intron 1:-13), g.3947C>G (p.R48G), g.4160G>T (p.A119S), g.8131C>G (p.L432V), g.8184C>T (p.D449D), g.8195A>G (p.N453S). Figure 1.…”

“…The coding region (exon II and III) of CYP1B1 was amplified from genomic DNA and sequenced as previously described (Bejjani et al, 1998;Stoilov et al, 1998). PCR products were gel-purified and subjected to dideoxy sequencing using sequencing primers described elsewhere (Bejjani et al, 1998).…”

Pharmacogenetics and Regulation of Human CytochromeP450 1B1: Implications in Hormone-Mediated Tumor Metabolism and a Novel Target for Therapeutic Intervention

“…Although a crystal structure for CYP1B1 has not been elucidated, its structure can be inferred based on conserved sequences found in many P450s (ref. 17; see Fig. 1A).…”

“…1A; ref. 17). However, increased basal mRNA levels of CYP1B1 have been observed in cell culture (109), suggesting a possible role for these polymorphisms in CYP1B1-mediated carcinogenesis.…”

Cancer Risk Assessment, Indicators, and Guidelines for Polycyclic Aromatic Hydrocarbons in the Ambient Air

“…There are at least four common mutations resulting in amino acid exchanges in the human CYP1B1 gene, which may explain some of the variation in human AHH activity (Stoilov et al 1998). …”