Cloning and expression of a novel human DNA binding protein, PO-GA

We have cloned a novel human DNA-binding protein from a HeLa cDNA expression library using the cognate DNA binding site of a transcription factor, PO-B. Further hybridization screening with the initial clone produced contiguous cDNA sequence of 4508 bp and a complete open reading frame encoding a 128 kDa protein, PO-GA. Northern analysis revealed a wide distribution of PO-GA mRNA in most human tissue. However, PO-GA mRNA levels were lower in lung and kidney and undetectable in placental tissue. A DNA-binding fragment of PO-GA expressed in E. Coli bound selectively to the PO-B element and other GA-rich double-stranded DNA sequences and to certain single-stranded DNA sequences. PO-GA has regions of homology to E. coli and yeast DNA ligases, and to proteins involved in DNA repair. Thus, in addition to a potential role in transcription, PO-GA may also be involved in DNA repair or replication.