Putative Interaction Proteins of the Ubiquitin Ligase Hrd1 in Magnaporthe oryzae

Abstract

The endoplasmic reticulum (ER) is the entry portal of the conventional secretory pathway where the newly synthesized polypeptides fold, modify, and assemble. The ER responses to the unfolded proteins in its lumen (ER stress) by triggering intracellular signal transduction pathways include the ER-associated degradation (ERAD) pathway and the unfolded protein response (UPR) pathway. In yeast and mammals, the ubiquitin ligase Hrd1 is indispensable for the ERAD pathway, and also Hrd1-mediated ERAD pathway plays a crucial role in maintaining homeostasis and metabolism of human beings. However, the underlying physiological roles and regulatory mechanism of the Hrd1-involved ERAD pathway in the plant pathogenic fungi are still unclear. Here, we identified the Hrd1 orthologous proteins from 9 different fungi and noticed that these Hrd1 orthologs are conserved. Through identification of MoHrd1 putative interacting proteins by co-immunoprecipitation assays and enrichment analysis, we found that MoHrd1 is involved in the secretory pathway, energy synthesis, and metabolism. Taken together, our results suggest that MoHrd1 is conserved among fungi and play an important role in cellular metabolism and infection-related development. Our finding helps uncover the mechanism of Hrd1-involved ERAD pathway in fungi and sheds a new light to understand the pathogenic mechanism of Magnaporthe oryzae.

Endoplasmic reticulum‐associated degradation mediated by MoHrd1 and MoDer1 is pivotal for appressorium development and pathogenicity of Magnaporthe oryzae

“…We have identified MoHrd1 (MGG_09205) as a homologue sharing amino acid sequence conservation with Hrd1p in S. cerevisiae (Jiang et al ., 2018). In addition, we performed a BLASTP search of the M. oryzae genome (http://fungidb.org/fungidb/) using the sequence of Der1p from S. cerevisiae as a query and named MoDer1 (MGG_06444).…”

“…We previously identified Hrd1 orthologous protein in M. oryzae and found that MoHrd1 could be crucial for the secretory pathway, energy synthesis and metabolism (Jiang et al ., 2018). In the current study, we found that ER‐locating proteins MoHrd1 and MoDer1 play crucial roles in vegetative growth, asexual reproduction and pathogenicity of M. oryzae .…”

Ubiquitination in the rice blast fungus Magnaporthe oryzae: from development and pathogenicity to stress responses

“…Hrd1 is a key E3 ligase of the endoplasmic reticulum-associated degradation (ERAD) pathway, and MoHrd1 is identified in M. oryzae. IP-MS data to separate putative interacting proteins of MoHrd1 revealed that MoHrd1 is involved in the secretory pathway, energy synthesis and metabolism (Jiang et al 2018). Cell biological and biochemical investigation results showed that both MoHrd1 and MoDer1 have conserved functions in the ERAD system, including ER localization, ERAD substrate degradation and the induction of unfolded protein response (UPR) in their knockout mutants.…”