Maize DNA polymerase 2 (an α-type enzyme) suffers major damage after seed deterioration

Abstract

AbstractDNA polymerase 2 holoenzyme is an α-type polymerase present as a major activity in 24-h germinated maize embryo axes. At this time, several of the polypeptides that compose this multisubunit enzyme are phosphorylated. During the germination of artificially deteriorated maize embryo axes, total DNA polymerase activity decreases by around 50% when compared with activity in non-deteriorated axes. DNA polymerase 2 appears to be damaged by the deterioration treatment, greatly reducing its activity. This decrease in activity is related to protein degradation during germination since the amount of both the holoenzyme and the different polymerase 2 subunits is reduced as imbibition progresses. The decrease in amount is more dramatic for some of the subunits than for others, i.e., the amount of the 90-kDa catalytic subunit is reduced by about half, whereas all other subunits totally disappear at different times during germination. The phosphorylation state of the different polypeptides is also greatly affected.