SSBP1 (F4E9N) Rabbit mAb #26087

The mitochondrial DNA replisome requires the activity of single-stranded DNA-binding protein (SSBP1, mtSSB), DNA Polymerase γ (POLG), and the mitochondrial DNA helicase (twinkle/PEO1) (1). SSBP1 enhances the functions of both POLG and PEO1 by binding to and stabilizing single-stranded DNA at the replication fork; knockdown of SSBP1 in vitro causes a gradual depletion of mitochondrial DNA and an acute depletion of 7S DNA (2). Mutations in SSBP1 underlie a variety of disorders, including optic atrophy, nephropathy (3), Pearson syndrome, Leigh syndrome, and Kearns-Sayre syndrome (4-6). SSBP1 has emerged as a potential therapeutic target for glioblastoma (7) and non-small cell lung cancer (NSCLC) (8), as controlled depletion of SSBP1 increases mitochondrial reactive oxygen species (ROS) and sensitizes these cancer cells to temozolomide and radiation therapy, respectively (7,8). The increase in mitochondrial ROS observed with SSBP1 depletion is linked to a corresponding decrease in nuclear ROS (9). ROS-sensing kinase Chk1 phosphorylates SSBP1 at Ser67, causing SSBP1 sequestration in the cytoplasm and limiting the translation of mitochondrial genes (9). This pathway may confer resistance to platinum-based therapies in ovarian cancers (9).