title: Plant and Human MORC Proteins Have DNA-Modifying Activities Similar to Type II Topoisomerases, but Require One or More Additional Factors for Full Activity.
abstract: To elucidate one or more mechanisms through which microrchidia (MORC) proteins impact immunity, epigenetic gene silencing, and DNA modifications, the enzymatic activities of plant MORCs were characterized. Previously, we showed that plant MORC1s have ATPase and DNA endonuclease activities. Here, we demonstrate that plant MORCs have topoisomerase type II (topo II)-like activities, as they i) covalently bind DNA, ii) exhibit DNA-stimulated ATPase activity, iii) relax or nick supercoiled DNA, iv) catenate DNA, and v) decatenante kinetoplast DNA. Mutational analysis of tomato SlMORC1 suggests that a K loop-like sequence is required to couple DNA binding to ATPase stimulation as well as for efficient SlMORC1's DNA relaxation and catenation activities and in planta suppression of INF1-induced cell death, which is related to immunity. Human MORCs were found to exhibit the same topo II-like DNA modification activities as their plant counterparts. In contrast to typical topo IIs, SlMORC1 appears to require one or more accessory factors to complete some of its enzymatic activities, since addition of tomato extracts were needed for ATP-dependent, efficient conversion of supercoiled DNA to nicked/relaxed DNA and catenanes and for formation of topoisomer intermediates. Both plant and human MORCs bind salicylic acid; this suppresses their decatenation but not relaxation activity.
authors.affiliation: 1 Boyce Thompson Institute, Ithaca, NY 14853, U.S.A.
authors.forename: Murli
authors.initials: M
authors.lastname: Manohar
authors.affiliation: 1 Boyce Thompson Institute, Ithaca, NY 14853, U.S.A.
authors.forename: Hyong Woo
authors.initials: HW
authors.lastname: Choi
authors.affiliation: 1 Boyce Thompson Institute, Ithaca, NY 14853, U.S.A.
authors.forename: Patricia
authors.initials: P
authors.lastname: Manosalva
authors.affiliation: 2 Institute for Cell and Molecular Biosciences, Newcastle University, NE2 4HH, U.K.; and.
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Austin
authors.affiliation: 3 Department of Microbiology, Cornell University, Ithaca, NY 14853, U.S.A.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Peters
authors.affiliation: 1 Boyce Thompson Institute, Ithaca, NY 14853, U.S.A.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Klessig
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D055162:Biocatalysis; D004247:DNA / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D008239:Lysine / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D004278:DNA, Superhelical; D009687:Nuclear Proteins; D010936:Plant Extracts; D010940:Plant Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II; D008239:Lysine; D020156:Salicylic Acid