J Biol Chem. 2010 Feb 16. [Epub ahead of print]
MYST-family lysine acetyltransferase facilitates ataxia telangiectasia mutated (ATM) kinase-mediated DNA damage response in Toxoplasma gondii
Vonlaufen N, Naguleswaran A, Coppens I, Sullivan WJ Jr.
Indiana University School of Medicine, United States;
The MYST family of lysine acetyltransferases (KATs) function in a wide variety of cellular operations, including gene regulation and the DNA damage response. Here we report the characterization of the second MYST family KAT in the protozoan parasite Toxoplasma gondii (TgMYST-B). Toxoplasma causes birth defects and is an opportunistic pathogen in the immunocompromised, the latter due to its ability to convert into a latent cyst (bradyzoite). We demonstrate that TgMYST-B can gain access to the parasite nucleus and acetylate histones. Over-expression of recombinant, tagged TgMYST-B reduces growth rate in vitro and confers protection from a DNA alkylating agent. Expression of mutant TgMYST-B produced no growth defect and failed to protect against DNA damage. We demonstrate that cells over-expressing TgMYST-B have increased levels of ATM kinase and phosphorylated H2AX, and that TgMYST-B localizes to the ATM kinase gene. Pharmacological inhibitors of ATM kinase or KATs reverse the slow growth phenotype seen in parasites over-expressing TgMYST-B. These studies are the first to show that a MYST KAT contributes to ATM kinase gene expression, further illuminating the mechanism of how ATM kinase is upregulated to respond to DNA damage.
PMID: 20159970 [PubMed - as supplied by publisher]