Thus, the xopD gene actually encodes a 760 amino acid polypeptide with a molecular weight of 85.7 kDa (GenBank Accession Number: BK007963) ( Figure 533.1). This means that the mature XopD protein contains an additional 215 amino acids at its N-terminus.

The correct ATG start site is located 645 base pairs upstream of the predicted start site. It is critical to note that in 2011 the xopD gene locus was reannotated.

Preliminary work, however, indicates that transcription factors controlling ethylene signal transduction are likely targets (Kim and Mudgett, unpublished). XopD host target substrates remain to be determined. This strongly suggests that XopD substrates are sumoylated plant proteins involved with critical nuclear function(s). Once XopD is translocated into plant cells, it is targeted to subnuclear foci within the nucleus. deconjugates) SUMO from its substrates by cleaving the isopeptide bond that links the C-terminus of SUMO to the epsilon-amine of a Lys residue on the target protein.Ĭonsistent with the hypothesis that XopD might mimic eukaryotic SUMO proteases, biochemical analysis of purified recombinant XopD enzyme and XopD expressed inside plant cells demonstrated that the bacterial enzyme possesses both SUMO peptidase and isopeptidase activity in vitro and in planta. Processed SUMO is then ligated to protein substrates by SUMO conjugating enzymes and (2) Ulp1 isopeptidase activity removes ( i.e. Ulp1 catalyzes two critical reactions in the SUMO pathway: (1) Ulp1 peptidase activity cleaves between the P1 and P1′ position in the invariant C-terminal sequence (-GlyGly↓XXX) of SUMO to its mature form (-GlyGly). SUMO proteases dynamically regulate the steady state of SUMO-protein conjugates and thus impact a number of cellular processes. Proteins that are post-translationally modified by SUMO are involved in the regulation of nuclear transport, cell cycle progression, transcription and the stress response. SUMO is a member of a family of ubiquitin-related proteins that are covalently linked to eukaryotic proteins by a conjugation system that operates analogously to the ubiquitin conjugation system. Ulp1 is a SUMO-specific protease that operates in the SUMO protein conjugation pathway. Based on this striking sequence homology, it was hypothesized that XopD mimicked a plant Ulp1-like protease inside the plant cell to alter host signaling induced by Xcv pathogenesis. Using BLAST and PROSITE analysis, it was discovered that the C-terminus of XopD shares primary sequence similarity with the C48 family of cysteine proteases and is most homologous to the C-terminal catalytic domain of the Ulp1 ubiquitin-like protein protease family that is highly conserved from yeast to mammals. XopD was identified as a novel, secreted effector encoded within the Xcv hrp T3S pathogenicity island. XopD was the first phytophathogenic T3S effector shown to exhibit a eukaryotic-like peptidase activity in vitro and in planta.

The emerging theme is that T3S effectors encode enzymes or scaffolding proteins that mimic the function of eukaryotic proteins to suppress different nodes in innate immunity signal transduction. Insight to T3S effector function thus has come primarily from the use of structural prediction programs and/or by solving effector structures. Elucidating T3S effector function is a challenge because their primary sequence shares limited sequence similarity with well characterized enzymes. Xanthomonas T3S effectors are called ‘Xops’ or Xanthomonas outer proteins based on conventional nomenclature. The Xcv T3S apparatus secretes and translocates ~35 protein substrates (referred generally as T3S effectors) into host cells. Like other plant and animal bacterial pathogens, Xcv uses the type III secretion (T3S) system to suppress host defense signal transduction to promote bacterial growth and pathogenesis. Xanthomonas campestris pathovar vesicatoria (Xcv) is a Gram-negative bacterium that causes bacterial spot disease in tomato and pepper. Jung-Gun Kim, Mary Beth Mudgett, in Handbook of Proteolytic Enzymes (Third Edition), 2013 Name and History

Dbd blight bug