Identification and functional characterization of an Rbx1 in an invertebrate Haliotis diversicolor supertexta

A heat shock protein 90 β isoform involved in immune response to bacteria challenge and heat shock from Miichthys miiuy

Heat shock protein 90 (HSP90) is highly conserved molecular chaperone that plays a critical role in cellular stress response. In this study, we reported the identification and functional analysis of a heat shock protein 90 gene from miiuy croaker (designated Mimi-HSP90). Mimi-HSP90 contained five conserved HSP90 protein family signatures and shared 89.6%-99.5% similarity with other known HSP90 β isoform. Homology analysis and structure comparison further indicated that Mimi-HSP90 should be β isoform member of the HSP90 family. The molecular evolutionary analysis showed that HSP90 was under an overall strong purifying select pressure among fish species. Mimi-HSP90 gene was constitutively expressed in ten examined tissues, and the expression level of liver was higher than in other tissues. The expression level of Mimi-HSP90 gene under bacterial infection and heat shock were analyzed by real-time quantitative RT-PCR, resulted in significant changes in liver, spleen, and kidney tissues. The purified recombinant pET-HSP90 protein was used to produce the polyclonal antibody in mice. The specificity of the antibody was determined by Western blot analysis. All results suggested that Mimi-HSP90 was involved in thermal stress and immune response in miiuy croaker.

Characterization and function of an E2-17 kDa (UBE2D) in an invertebrate Haliotis diversicolor supertexta

Ubiquitin-conjugating enzymes (UBE2s or E2s) are characterized by the presence of a highly conserved ubiquitin-conjugating (UBC) domain, which predominantly determines the type of ubiquitin chains and directly controls the cellular fate of the substrate. In this study, an E2 homolog was identified and functionally characterized in abalone, which we named ab-UBE2D. The full-length cDNA consists of 1005 bp with an ORF encoding a protein of 147 amino acids. The deduced amino acid sequence shows ab-UBE2D shares conserved UBC domain with other E2 proteins and belongs to class I E2 enzyme family, which are further confirmed by phylogenetic tree analysis. Real-time PCR and western blot analyses showed that ab-UBE2D was ubiquitously expressed in abalone and the expression level of ab-UBE2d was significantly induced by LPS and Poly (I:C). Immunofluorescence microscopy staining demonstrated that native ab-UBE2D was mainly distributed in the cytoplast. Ubiquitination assay showed that ab-UBE2D had ubiquitin conjugating activity to form the enzyme-(Ub)n conjugates. Taken together, these results strongly suggest that ab-UBE2D is an E2 homolog and it may be involved in the immune response of abalone, Haliotis diversicolor supertexta.