Human C6orf211 encodes Armt1, a protein carboxyl methyltransferase that targets PCNA and is linked to the DNA damage response
- Cell Rep. 2015 Mar 3;10(8):1288-96. doi: 10.1016/j.celrep.2015.01.054.
- 1. Department of Biochemistry, University of California, Riverside, Riverside, CA 92521, USA; School of Biotechnology, Amrita University, Kollam, Kerala 690525, India.
- 2. Maine Institute for Human Genetics and Health, Bangor, ME 04401, USA.
- 3. Department of Hematology and Oncology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
- 4. Maine Institute for Human Genetics and Health, Bangor, ME 04401, USA; Department of Hematology and Oncology, Indiana University School of Medicine, Indianapolis, IN 46202, USA. Electronic address: [email protected].
Recent evidence supports the presence of an L-glutamyl methyltransferase(s) in eukaryotic cells, but this enzyme class has been defined only in certain prokaryotic species. Here, we characterize the human C6orf211 gene product as "acidic residue methyltransferase-1" (Armt1), an enzyme that specifically targets proliferating cell nuclear antigen (PCNA) in breast Cancer cells, predominately methylating glutamate side chains. Armt1 homologs share structural similarities with the SAM-dependent methyltransferases, and negative regulation of activity by automethylation indicates a means for cellular control. Notably, shRNA-based knockdown of Armt1 expression in two breast Cancer cell lines altered survival in response to genotoxic stress. Increased sensitivity to UV, adriamycin, and MMS was observed in SK-Br-3 cells, while in contrast, increased resistance to these agents was observed in MCF7 cells. Together, these results lay the foundation for defining the mechanism by which this post-translational modification operates in the DNA damage response (DDR).