Analysis of the Chicken GPAT/AIRC Bidirectional Promoter for de Novo Purine Nucleotide Synthesis

Abstract

GPAT and AIRC encode two enzymes that catalyze steps 1 and 6 plus 7, respectively, of the de novo purine biosynthetic pathway. The chicken genes are closely linked and divergently transcribed from an approximately 230-base pair intergenic region. The promoter was scanned by deletion mutagenesis in a bireporter vector that allowed assay of transcriptional activity in both directions in transfected HepG2 and chicken LMH cells. Three classes of deletions were obtained: those affecting bidirectional transcription, those predominantly affecting GPAT transcription, and those predominantly affecting AIRC transcription. Defects in bidirectional transcription resulted from removal of an initiator-like element overlapping the AIRC transcription start site, as well as deletions removing a series of GC and CCAAT boxes from the AIRC proximal half of the promoter and a CCAAT-containing segment from the GPAT side. Several regions in the GPAT proximal half of the promoter, including an octamer-like motif downstream from the transcription start site, were required predominantly for GPAT expression. Evidence for interaction of HeLa nuclear proteins with some of these sites was obtained by gel retardation, DNase I, and methylation interference assays. Overall, the results showed that the intergenic region is an integrated bidirectional promoter and that a novel initiator-like element plays a central role in coordinating expression of the divergently transcribed AIRC and GPAT genes.

Combined effect of mutations in ADSL and GARS-AIRS-GART genes on IMP content in chickens

“…Gavalas and Zalkin (1995) reported that GPAT and ARIC genes, which catalyse the first and sixth steps in de novo purine synthesis were closely linked and divergently transcribed from intergenic regions of approximately 230 bp in chickens. Chen (2004), Chai et al (2005) chose AMPD1 gene as candidate gene and analysed a 500-bp fragment of this gene using PCR-SSCP method in different chicken breeds.…”

The DNA Element Controlling Expression of the Varicella-Zoster Virus Open Reading Frame 28 and 29 Genes Consists of Two Divergent Unidirectional Promoters Which Have a Common USF Site

“…Thus, these combined results strengthen the idea that the basis of the differential regulation of these genes during latency may lie within the sequence of the regulatory element itself. fungi, and viruses, and a recent report indicates that more than 10% of the genes in the human genome may be divergently transcribed from such promoters (9,17,19,27,36,42,51,(53)(54)(55)(56)(61)(62)(63). These regulatory sequences fall into two general categories.…”

Systematic Analysis of Head-to-head Gene Organization: Evolutionary Conservation and Potential Biological Relevance

“…Some head-to-head genes are positively correlated and function in the same pathway, such as human collagen genes COL4A1/COL4A2 [1,13] and chicken genes GPAT/AIRC involved in de novo purine nucleotide synthesis [14]; some are coregulated in a common window of the cell cycle, such as murine genes RanBP1/Htf9-c [5,15]; some are coordinated to respond to induction signals, for example, human genes HSP60/HSP10 [16]. However, there are also some rare examples of negatively correlated head-to-head genes, such as mouse genes TK/KF [12].…”