A New Class of Ubiquitin Extension Proteins Secreted by the Dorsal Pharyngeal Gland in Plant Parasitic Cyst Nematodes

Abstract

By performing cDNA AFLP on pre- and early parasitic juveniles, we identified genes encoding a novel type of ubiquitin extension proteins secreted by the dorsal pharyngeal gland in the cyst nematode Heterodera schachtii. The proteins consist of three domains, a signal peptide for secretion, a mono-ubiquitin domain, and a short C-terminal positively charged domain. A gfp-fusion of this protein is targeted to the nucleolus in tobacco BY-2 cells. We hypothesize that the C-terminal peptide might have a regulatory function during syncytium formation in plant roots.

Ubiquitination during Plant Immune Signaling

“…Intriguingly, the stylet-secreted protein cocktail of the cyst nematode Heterodera schachtii contains a new class of ubiquitin with an atypical C-terminal extension (Tytgat et al, 2004). A study to characterize the full stylet secretome identified two ubiquitin hydrolases, a ubiquitin-activating enzyme as well as an SKP1-like protein (Bellafiore et al, 2008).…”

Nematodes. Sophisticated Parasites of Legumes

“…Expression of nematode CM in soybean tissues affected vascular tissue differentiation and was indirectly related to local indole-3-acetic acid concentrations and cellular partitioning of chorismate (Doyle and Lambert, 2003). Another group of candidate secreted nematode parasitism gene products that may also augment host cellular metabolism includes members of the proteasome (Skp-1, RING-H2, and ubiquitin extension protein) with significant similarity to plant genes involved in selective host cell protein degradation (Gao et al, 2003;Tytgat et al, 2004). If secreted into plant cells by nematodes, mimics of the plant proteasome may regulate host cell phenotype at the protein level to promote a compatible plantnematode interaction.…”

The Novel Cyst Nematode Effector Protein 19C07 Interacts with the Arabidopsis Auxin Influx Transporter LAX3 to Control Feeding Site Development

“…Identification of putative effector proteins in H. schachtii has been accomplished, with many ortholog genes having a very high degree of sequence similarity and esophageal gland expression patterns (Patel et al, 2008). For example, H. schachtii ubiquitins (UBIs) have greater than 90% sequence identity with HgUBIs (Tytgat et al, 2004); Hs10A06 has 86% sequence identity with Hg10A06 ; the H. schachtii cellulose-binding protein (CBP) has between 94% and 97% sequence homology to H. glycines CBP isoforms (Hewezi et al, 2008); the Hs4F01 annexin-like protein has 92% sequence identity to Hg4F01 (Patel et al, 2010); and H. schachtii CLAVATA3/ ESR-like (CLE) proteins have greater than 80% homology with HgCLEs (Wang et al, 2010b), with the H. schachtii transcripts localizing to the same esophageal gland cell(s) as the H. glycines orthologs.…”