A variety of service and collaborative projects in protein identification have been or are being carried out within the Mass Spectrometry Research and Support Group with approximately 4000 samples analyzed from 39 scientists representing 23 principal investigators or core heads from 6 laboratory branches and the DNTP. One large effort is in support of the Protein Expression Core Facility (PECF) and Dr. Bob Petrovich. The Role of the MSRSG is to confirm gene expression at the protein level prior to the PECF handing materials over to their users. Other published and unpublished projects that are still ongoing include: Identification of bacterial pathogens by MALDI-MS David Kurtz Identification of binding partners of GRbeta (Archer); Glis3 (Jetten); Rubicon (Martinez); GATA3 (Wade); Grc3/Las1 (Stanley); TSEN (Stanley); GABPalpha (Jothi); RRM3 (Kunkel); SMCHD1 (Shaw); HNF4alpha (Wade); APE2 (Williams) Additional projects focused on the identification of proteins that interacted with RNA or DNA elements or with inositol phosphates. These projects include: ER binding elements (Korach); ROR binding elements (Negishi); IP7 and IP8 binding proteins (Shears); Sohlh2 RNA binders (Hall) With Dr. R. Scott Williams: Topoisomerase 2 (TOP2) DNA transactions are essential for life, and proceed via formation of the TOP2 cleavage complex (TOP2cc), a covalent enzyme-DNA reaction intermediate that is vulnerable to trapping by potent anticancer TOP2 drugs. How genotoxic TOP2 DNA-protein crosslinks are resolved is unclear. Here, we show that the SUMO ligase ZATT (ZNF451) is a multifunctional DNA repair factor that controls cellular responses to TOP2 damage. ZATT binding to TOP2cc facilitates a proteasome-independent Tyrosyl-DNA phosphodiesterase 2 (TDP2) hydrolase activity on stalled TOP2cc. The ZATT SUMO ligase activity further promotes TDP2 interactions with SUMOylated TOP2, regulating efficient TDP2 recruitment through a split-SIM SUMO2 engagement platform. These findings uncover a ZATTTDP2 catalyzed and SUMO2-modulated pathway for direct resolution of TOP2cc. The specific contribution of the Mass Spectrometry Research and Support Group was to identify the proteins that immunoprecipitated with Tdp2. This resulted in the discovery of ZATT as a factor involved in DNA repair. Additional projects that have required more than negligible resources include efforts performed with the Blackshear, Garantziotis, and Hu laboratories.
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