Meloidogyne incognita PASSE-MURAILLE (MiPM) Gene Encodes a Cell-Penetrating Protein That Interacts With the CSN5 Subunit of the COP9 Signalosome

Abstract

The pathogenicity of phytonematodes relies on secreted virulence factors to rewire host cellular pathways for the benefits of the nematode. In the root-knot nematode (RKN) Meloidogyne incognita, thousands of predicted secreted proteins have been identified and are expected to interact with host proteins at different developmental stages of the parasite. Identifying the host targets will provide compelling evidence about the biological significance and molecular function of the predicted proteins. Here, we have focused on the hub protein CSN5, the fifth subunit of the pleiotropic and eukaryotic conserved COP9 signalosome (CSN), which is a regulatory component of the ubiquitin/proteasome system. We used affinity purification-mass spectrometry (AP-MS) to generate the interaction network of CSN5 in M. incognita-infected roots. We identified the complete CSN complex and other known CSN5 interaction partners in addition to unknown plant and M. incognita proteins. Among these, we described M. incognita PASSE-MURAILLE (MiPM), a small pioneer protein predicted to contain a secretory peptide that is up-regulated mostly in the J2 parasitic stage. We confirmed the CSN5-MiPM interaction, which occurs in the nucleus, by bimolecular fluorescence complementation (BiFC). Using MiPM as bait, a GST pull-down assay coupled with MS revealed some common protein partners between CSN5 and MiPM. We further showed by in silico and microscopic analyses that the recombinant purified MiPM protein enters the cells of Arabidopsis root tips in a non-infectious context. In further detail, the supercharged N-terminal tail of MiPM (NTT-MiPM) triggers an unknown host endocytosis pathway to penetrate the cell. The functional meaning of the CSN5-MiPM interaction in the M. incognita parasitism is discussed. Moreover, we propose that the cell-penetrating properties of some M. incognita secreted proteins might be a non-negligible mechanism for cell uptake, especially during the steps preceding the sedentary parasitic phase.

Plant Proteins and Processes Targeted by Parasitic Nematode Effectors

“…Like other classes of plant pathogens that have to overcome host defenses, PPNs produce effectors that converge on evolutionarily conserved host targets called “hubs” (Carella et al, 2018). The M. incognita “Passe-Muraille” peptide effector, for example, interacts with subunit 5 of the COP9 signalosome (CSN5) (Bournaud et al, 2018), a hub targeted by bacterial, fungal and viral effectors (Mukhtar et al, 2011; Weßling et al, 2014). The function of CSN5 in RKN parasitism remains unknown, but this target protein is known to be involved in plant salicylic acid-mediated defense (Kazan and Lyons, 2014).…”

MiDaf16-like and MiSkn1-like gene families are reliable targets to develop biotechnological tools for the control and management of Meloidogyne incognita

“…Interestingly, without targeting all the members of these families because they are highly conserved in nematodes and other animals, these two gene families may be potential targets for the development of NBTs to impair the defense pathways of PPNs during plant parasitism. M. incognita is a RKN 10 , an important plant pathogen causing economic losses in several crops worldwide 11 , and an excellent model system for obligate sedentary endoparasitic PPNs 13,21 . Our findings confirm that in planta downregulation of MiDaf16-like1, MiSkn1-like1 (single-gene silencing), or both genes simultaneously (double-gene silencing), makes nematodes more susceptible to stress conditions during parasitism, significantly reducing the number of galls and eggs, NRF, and, consequently, decreasing the source of inoculum.…”

COP9 Signalosome CSN4 and CSN5 Subunits Are Involved in Jasmonate-Dependent Defense Against Root-Knot Nematode in Tomato

“…Potato cyst nematode CLAVATA3/ENDOSPERM SURROUNDING REGION-like effector can interact with the potato CLAVATA2-like receptor, which controls the fate of stem cells in the shoot apical meristem, to promote nematode parasitism (Chen et al, 2015). Recently, Bournaud et al (2018) reported that soybean CSN5 interacts with the M. incognita effector MiPM, which may trigger a host endocytosis pathway to penetrate the cell and may regulate the endosomal sorting of MiPM. Based on these results, we can speculate that the CSN may interact with more RKN effectors and disrupt the perception of nematode effector or effector-associated signaling pathways to interfere with RKN parasitism.…”

“…However, a CSN5-like gene negatively regulates wheat ( Triticum aestivum L.) leaf rust resistance (Zhang et al, 2017a). Recently, Bournaud et al (2018) found that soybean ( Glycine max ) CSN5 interacts with the M. incognita Passe-Muraille ( MiPM ) gene which encodes a cell-penetrating protein. However, the precise role of CSN in plant defense against RKN infection and the relationship between CSN and JA signaling pathway in tomato RKN resistance remain unclear.…”