Chromosomal location and expression of the single-copy gene encoding high-mobility-group protein HMG-I/Y in Arabidopsis thaliana

A cDNA encoding the HMG-I/Y protein from Arabidopsis thaliana has been isolated and characterised by nucleotide sequencing. The 903 bp cDNA contains a 612 bp open reading frame encoding a protein of 204 amino acid residues showing homology to HMG-I/Y proteins from other plant species. The protein contains four copies of the AT-hook motif which is involved in binding A/T-rich DNA. Southern blotting showed that the HMG-I/Y gene was present in a single copy in the Arabidopsis genome. The gene was localised to the top of chromosome 1 by RFLP analysis of F₈ recombinant inbred lines. Northern blotting showed that the gene was expressed in all organs examined, with the highest expression in flowers and developing siliques.     

A conformational study of the sequence specific binding of HMG-I (Y) with the bovine interleukin-2 cDNA

The DNA sequence specific interaction of the high mobility group non-histone protein HMG-I (Y) with the 3' untranslated region of the bovine interleukin-2 cDNA has been studied. Circular dichroism and thermal denaturation studies suggest that HMG-I (Y) alters the conformational state and increases the thermal stability of the DNA. Additionally, amino acid sequence analysis suggests that the previously identified non-histone protein HMG-Y is an isoform of HMG-I.     

Complete murine cDNA sequence, genomic structure, and tissue expression of the high mobility group protein HMG-I(Y)

A cDNA coding for the non-histone chromosomal protein HMG-I, or its isoform HMG-Y, was isolated from a murine Friend cell library using synthetic oligonucleotide hybridization probes. Sequence analysis showed that the 1670-base pair full length cDNA insert consists of a 201-base pair, G/C-rich (74%), 5'-untranslated region, a 288-base pair amino acid coding sequence, and an unusually long 1182-base pair 3'-untranslated region. The deduced 96-residue amino acid coding sequence of the murine HMG-I(Y) cDNA is very similar to the reported amino acid sequence of human HMG-I, except that it lacks 11 internal amino acids reported in the human protein. Based on Southern blot hybridization analysis of genomic DNA, there appear to be fewer than five copies of HMG-I(Y) genes in the haploid murine genome. These murine HMG-I(Y) genes contain a large (at least 890 base pairs) exon that includes most, or all, of the 3'-untranslated region; whereas the much shorter 5'-untranslated region and amino acid coding sequences are interrupted by at least one intron. A single size class (approximately 1700 nucleotides in murine cells and 2000 nucleotides in human cells) of HMG-I(Y) mRNAs was detected at high levels in total RNA extracts from rapidly dividing, transformed cells, but to a lesser extent, or not at all, in extracts from slowly or non-dividing cells.     

An IL-2 response element in the human IL-2 receptor alpha chain promoter is a composite element that binds Stat5, Elf-1, HMG-I(Y) and a GATA family protein.

Expression of the human interleukin-2 (IL-2) receptor alpha chain gene is potently upregulated by its own ligand, IL-2. In this study, we characterize an essential upstream IL-2 response element that contains both consensus and non-consensus GAS motifs, two putative Ets binding sites (EBS), one of which overlaps the consensus GAS motif, and a GATA motif, which overlaps the non-consensus GAS motif. We demonstrate that although the individual components of this element do not respond to IL-2, together they form a composite element capable of conferring IL-2 responsiveness to a heterologous promoter. Multiple factors including Stat5, Elf-1, HMG-I(Y) and GATA family proteins bind to the IL-2 response element and mutation of any one of these binding sites diminishes the activity of this element. An unidentified Ets family protein binds to the EBS overlapping the consensus GAS motif and appears to negatively regulate the human IL-2R alpha promoter. Thus, IL-2-induced IL-2R alpha promoter activity requires a complex upstream element, which appears to contain binding sites for both positive and negative regulatory factors.     

Replication of human papillomavirus (HPV) DNAs supported by the HPV type 18 E1 and E2 proteins.

Transient replication of human papillomavirus (HPV) type 18 DNA was shown to require the viral E1 and E2 proteins. A 108-bp sequence within the long control region (nucleotides 12 to 119) was sufficient to function as the origin, but maximal replication required a region of 177 bp from positions 7800 to 7857 and 1 to 119 of HPV-18. The E1 and E2 proteins of HPV-18 also supported transient replication of plasmids containing the origins of HPV-1a and bovine papillomavirus type 1 to low levels. Interestingly, the level of replication observed with the HPV-6b origin was higher than that obtained with the homologous HPV-18 origin.