Lotus japonicus Clathrin Heavy Chain1 Is Associated with Rho-Like GTPase ROP6 and Involved in Nodule Formation

Abstract

Mechanisms underlying nodulation factor signaling downstream of the nodulation factor receptors (NFRs) have not been fully characterized. In this study, clathrin heavy chain1 (CHC1) was shown to interact with the Rho-Like GTPase ROP6, an interaction partner of NFR5 in Lotus japonicus. The CHC1 gene was found to be expressed constitutively in all plant tissues and induced in Mesorhizobium loti-infected root hairs and nodule primordia. When expressed in leaves of Nicotiana benthamiana, CHC1 and ROP6 were colocalized at the cell circumference and within cytoplasmic punctate structures. In M. loti-infected root hairs, the CHC protein was detected in cytoplasmic punctate structures near the infection pocket along the infection thread membrane and the plasma membrane of the host cells. Transgenic plants expressing the CHC1-Hub domain, a dominant negative effector of clathrin-mediated endocytosis, were found to suppress early nodulation gene expression and impair M. loti infection, resulting in reduced nodulation. Treatment with tyrphostin A23, an inhibitor of clathrin-mediated endocytosis of plasma membrane cargoes, had a similar effect on down-regulation of early nodulation genes. These findings show an important role of clathrin in the leguminous symbiosis with rhizobia.

Ectopic activation of cortical cell division during the accommodation of arbuscular mycorrhizal fungi

“…Indeed, CME has recently been shown to play a fundamental role in legume-rhizobium interactions: a 60% reduction in the abundance of L. japonicus Clathrin Heavy Chain 1 (LjCHC1) transcripts (but not LjCHC2) has been shown to strongly reduce rhizobial infection and nodule development (Wang et al, 2015). In the light of this finding, the consistent 30% upregulation of M. truncatula CHC2 (but not MtCHC1) during AM colonization opens the intriguing possibility that the two genes act in alternative pathways controlling legume mycorrhiza formation or nodulation, although more detailed analyses going beyond the scope of the present research will be required to clarify this point.…”

Identification of the phosphorylation targets of symbiotic receptor‐like kinases using a high‐throughput multiplexed assay for kinase specificity

“…Also, LYK3 potentially phosphorylates a clathrin heavy chain protein (Medtr5g082900), whereas a sorting nexin 2B (Medtr5g073280), a vacuolar protein sorting protein (Medtr4g056480) and an SH3 domain protein (Medtr8g100105) are putative targets of NORK. Recently, a clathrin heavy chain protein CHC1 that interacts with ROP6, an interaction partner of NFR5 (an ortholog of LYK3 in the other model legume L. japonicus ) has been implicated in nodulation, and Medtr5g082900 may play a similar role in Medicago (Wang et al ., ). Taken together these symbiotic receptor‐like kinases phosphorylate proteins involved in ubiquitination or vesicle trafficking, either directly or indirectly.…”

“…Medicago (Wang et al, 2015). Taken together these symbiotic receptor-like kinases phosphorylate proteins involved in ubiquitination or vesicle trafficking, either directly or indirectly.…”

ALotus japonicusE3 ligase interacts with the Nod factor receptor 5 and positively regulates nodulation

“…Along this line, and although NFR5 internalization from the plasma membrane has not been shown directly as yet, an association of NFR5 with the clathrin-mediated endocytosis has been proposed (Wang et al, 2015b). A clathrin protein (CHC1) was shown to interact with the Rho-like GTPase ROP6 (Wang et al, 2015a), an interacting partner of NFR5 (Ke et al, 2012) in L. japonicus . Interestingly, ROP6 silencing in roots by RNAi did not affect the rhizobium entry in root hairs, but inhibited the IT growth through the root cortex, which resulted in the development of fewer nodules per plant (Ke et al, 2012).…”