MORC Proteins: Novel Players in Plant and Animal Health.

Aline Koch,Hong-Gu Kang,Karl-Heinz Kogel,D'Maris A Dempsey,Jens Steinbrenner,Daniel F Klessig

doi:10.3389/fpls.2017.01720

Aline Koch, Hong-Gu Kang + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2017.01720

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Abstract

Microrchidia (MORC) proteins comprise a family of proteins that have been identified in prokaryotes and eukaryotes. They are defined by two hallmark domains: a GHKL-type ATPase and an S5 fold. MORC proteins in plants were first discovered via a genetic screen for Arabidopsis mutants compromised for resistance to a viral pathogen. Subsequent studies expanded their role in plant immunity and revealed their involvement in gene silencing and transposable element repression. Emerging data suggest that MORC proteins also participate in pathogen-induced chromatin remodeling and epigenetic gene regulation. In addition, biochemical analyses recently demonstrated that plant MORCs have topoisomerase II (topo II)-like DNA modifying activities that may be important for their function. Interestingly, animal MORC proteins exhibit many parallels with their plant counterparts, as they have been implicated in disease development and gene silencing. In addition, human MORCs, like plant MORCs, bind salicylic acid and this inhibits some of their topo II-like activities. In this review, we will focus primarily on plant MORCs, although relevant comparisons with animal MORCs will be provided.

Highlights

Reviewed by: Zdravko Lorkovic, Gregor Mendel Institute (OAW), Austria Xin-Jian He, National Institute of Biological Sciences, China
When HRT detects the presence of the TCV coat protein (CP), it triggers the activation of plant immune responses, including increased defense gene expression, accumulation of the defense hormone salicylic acid (SA), and development of a hypersensitive response (HR), a form of programmed cell death that occurs at the site(s) of pathogen entry (Kang et al, 2008)
The combined GHKLS5 domains constitute an active “GHKL-type ATPase” module involved in ATP binding and hydrolysis; these activities have been demonstrated for many GHKL superfamily members in prokaryotes and mammals (Ban and Yang, 1998; Smith and Maxwell, 1998; Hu et al, 2003; Meyer et al, 2003; Corbett and Berger, 2005), and for MORC proteins identified in several plant species, such as barley, Arabidopsis, potato, tomato, and tobacco (Kang et al, 2008; Lorkovicet al., 2012; Langen et al, 2014; Manosalva et al, 2015; Manohar et al, 2017)

Summary

Introduction

The combined GHKLS5 domains constitute an active “GHKL-type ATPase” module involved in ATP binding and hydrolysis; these activities have been demonstrated for many GHKL superfamily members in prokaryotes and mammals (Ban and Yang, 1998; Smith and Maxwell, 1998; Hu et al, 2003; Meyer et al, 2003; Corbett and Berger, 2005), and for MORC proteins identified in several plant species, such as barley, Arabidopsis, potato, tomato, and tobacco (Kang et al, 2008; Lorkovicet al., 2012; Langen et al, 2014; Manosalva et al, 2015; Manohar et al, 2017)

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