Urochordates carry multiple genes for goose-type lysozyme and no genes for chicken- or invertebrate-type lysozymes

Abstract

Genome clones and expressed sequence tags (ESTs) from the ascidian Ciona intestinalis and from the larvacean Oikopleura dioica were analysed for the presence of lysozyme-encoding genes. Two genes were found to potentially code for goose-type lysozymes in Oikopleura, while three or possibly more g-type proteins form the lysozyme complement of C. intestinalis, and at least one of these genes from each species is expressed based on EST data. No genes for chicken- or invertebrate-type lysozymes were found in either urochordate species. Consistent with this finding, extracts of Oikopleura animals possessed hydrolysing activity on bacterial cell walls, and this activity was not inhibited in the presence of a known inhibitor of chicken-type lysozyme. A wide range of isoelectric points for the predicted lysozymes from Ciona (pI 4.4, 6.4 and 9.9) and from Oikopleura (pI 5.0 and 8.0) suggests tissue-specific adaptations as well as specific functional roles of the lysozymes. Comparisons of gene structures, encoded sequences, cysteine residue content and their positions in the proteins indicate that the g-type lysozymes of Ciona intestinalis are more closely related to those of vertebrates than are the g-type lysozymes of Oikopleura. Multiple genes from each species may result from separate and lineage-specific duplications followed by functional specialisation.

Three goose-type lysozymes in the gastropod Oncomelania hupensis: cDNA sequences and lytic activity of recombinant proteins

“…In some vertebrates such as in human and zebrafish, two g-type lysozyme genes have been reported (Irwin and Gong, 2003;Callewaert and Michiels, 2010), and two genes coding for g-type lysozymes have been identified in genome database of urochordate, the larvacean Oikopleura dioica, and three or more g-type lysozymes in the ascidian Ciona intestinalis with the expression of at least one gene (Nilsen et al, 2003) However, only one gtype lysozyme gene has been reported from bivalve molluscs (Zou et al, 2005;Zhao et al, 2007) despite some efforts in sequencing genomes of scallops (e.g. Zhang et al, 2007).…”

“…In a review on lysozymes, Callewaert and Michiels (2010) identified the presence of g-type lysozyme in genome database of amphibian vertebrates. It was initially considered that g-type lysozyme was restricted to vertebrates (Irwin and Gong, 2003), but biologically functional g-type lysozymes have been identified in urochordates (Irwin and Gong, 2003;Nilsen et al, 2003) and in mollusc invertebrates (see Callewaert and Michiels, 2010). It appears likely that molluscs are the only non-chordate animals from which the g-type lysozyme has been reported, and so far only from bivalve molluscs, i.e.…”

Identification of a bacterial inhibitor against g-type lysozyme

“…Similarly, g-type lysozyme has been linked to innate immune defense in bivalves. In the Zhikong scallop Chlamys farreri, specific nucleotide polymorphisms in the promoter region of the g-type [15,19], Monchois et al [12], Nilsen et al [33] and Van Herreweghe et al [18] except those marked with '*', which are from unpublished data from the authors ? Strong inhibition, ± weak inhibition, -no inhibition, n.t.…”

“…Furthermore, in the current work, the affinity of PliG was determined only against SalG, and it is possible that g-type lysozymes from mammals, birds, invertebrates or even some bacterial lytic transglycosylases with a g-type lysozyme domain [32] will show a higher affinity. In this context, it is noteworthy that we observed inhibition of the g-type lysozymes in extracts of the Urochordate Oikopleura dioica [33] (data not shown). The specific interaction of PliG and SalG was also investigated by affinity chromatography using the inverse configuration as in SPR, i.e.…”

Molecular characterisation, evolution and expression analysis of g-type lysozymes in Ciona intestinalis

“…The g-type lysozyme was initially identified as an antibacterial enzyme in egg whites from the Embden goose (Canfield and McMurry, 1967), but it was later found to exist in the egg whites of several other bird species (Prager et al, 1974). More recently, the g-type lysozyme has been identified in vertebrate species, including mammals (Nakano and Graf, 1991), fish (Mohanty and Sahoo, 2010), urochordates (Nilsen et al, 2003) and molluscs (Zhao et al, 2007;Zhang et al, 2012).…”