RNA polymerase from human influenza viruses A, B and C is a heterotrimric enzyme, made up of three different subunits. It performs the crucial function both genome replication as well transcription. One subunits, acidic protein subunit (PA), suggested to an endonuclease in ‘cap-snatching’ mechanism, unique viruses. However, by multiple sequence alignment (MSA) analysis, it was found that PA sub...

Fen1 or maturation factor 1 is a 5'-3' exonuclease essential for the degradation of the RNA primer-DNA junctions at the 5' ends of immature Okazaki fragments prior to their ligation into a continuous DNA strand. The gene is also necessary for repair of damaged DNA in yeast. We report that human proliferating-cell nuclear antigen (PCNA) associates with human Fen1 with a Kd of 60 nM and an appare...

The expansion of CAG·CTG repeat tracts is responsible for several neurodegenerative diseases, including Huntington disease and myotonic dystrophy. Understanding the molecular mechanism of CAG·CTG repeat tract expansion is therefore important if we are to develop medical interventions limiting expansion rates. Escherichia coli provides a simple and tractable model system to understand the fundam...

Three recent papers reveal a fascinating link between pol II termination and ribonucleolytic decay of the nascent transcript by a 5'-3' exonuclease (yeast Rat1 and human Xrn2). The exonuclease travels with pol II and gains access to the nascent RNA after endonucleolytic cleavage at the poly(A) site or at a second cotranscriptional cleavage site (CoTC). It is then thought to track in a 5'-3' dir...

Platinum metal was sequence-specifically deposited on the DNA block copolymer synthesized by the Klenow fragment of E. coli DNA polymerase I (3'-5' exonuclease deficient).