Hosts and viruses fight for survival has resulted in a great arsenal of molecular weapons. The host combats DNA viruses by preventing expression of their genomes and by destroying their transcripts. These tactics are known as transcriptional and post-transcriptional gene silencing (TGS and PTGS), respectively. On the other side, surviving viruses must have evolved strategies to subvert the host defense and colonize. The molecular arms race between host and virus, and the effectiveness of their deployment are key determinants of the outcome of the battle.
In a recent publication in eLife, Xiuren Zhang‘s laboratory in the Dept. of Biochemistry and Biophysics at Texas A&M and collaborators from the State Key Laboratory of Plant Genomics and the State Key Laboratory of Rice Biology, reported a new battlefield between plant and virus. They found that the plant host uses a histone methyltransferase, Kryptonite (KYP), to condense the viral genome and prevent infection. Alongside, the virus counters this TGS strategy by expressing the viral protein TrAP, to directly inhibit KYP.
Their work demonstrates the essential role of KYP as a defense mechanism against the virus, and it is the first evidence of virus interference with an enzyme in the TGS pathway. Opening the doors to biotechnological applications in the development of virus resistant crops and new tools for the manipulation of gene expression. Commentaries on the work can also be found at eLife and Nature Reviews Genetics.