Novel conserved human DNA sequence supports expression of long genes

Abstract

AbstractThe study described here was carried out to explore the properties of a novel DNA sequence element found concentrated in five human chromosomes, 16-18, 20 and Y. The new DNA sequence, 1519 bp in length and called t1519, was found throughout the high abundance chromosomes, but only rarely elsewhere in the genome. BLAST analysis revealed the highest number of t1519 matches is in chromosome 18 (1429 matches) and the lowest in chromosome 16 (500). Nucleotide sequence homology was very good in all five high abundance human chromosomes; identities of 80% or more were observed in hundreds of annotated matches in each chromosome. Poor similarity, however, was observed in all non-human species examined. A few similarities were seen in chimpanzee chromosome 5 and in gorilla chromosome 7. Only poor sequence matches were found in mouse. Further analysis of human chromosomes 16 and 17 was performed with the goal of identifying the function of t1519. The focus was on t1519 matches found in protein coding genes and on the length and expression level of those genes. Results identified t1519 matches in both short (<200kb) and long (>200kb) genes while genes lacking t1519 were found only in the short population. Similarly, while the short genes included both high and low expression genes and t1519-positive and t1519-negative genes, all long genes were t1519 positive and weak in expression. The observations are interpreted to indicate that t1519 elements function to adjust the expression level of long genes so that the host can benefit from the functions they encode without permitting them to overextend the transcription machinery of the cell.