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Plant and Human MORC Proteins Have DNA-Modifying Activities Similar to Type II Topoisomerases, but Require One or More Additional Factors for Full Activity

Lookup NU author(s): Professor Caroline AustinORCiD


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© 2017 The American Phytopathological Society. 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 IIlike 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.

Publication metadata

Author(s): Manohar M, Choi HW, Manosalva P, Austin CA, Peters JE, Klessig DF

Publication type: Article

Publication status: Published

Journal: Molecular Plant-Microbe Interactions

Year: 2017

Volume: 30

Issue: 2

Pages: 87-100

Online publication date: 01/02/2017

Acceptance date: 02/04/2016

ISSN (print): 0894-0282

Publisher: American Phytopathological Society


DOI: 10.1094/MPMI-10-16-0208-R


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