Cloning and sequencing of a molluscan endo‐β‐1,4‐glucanase gene from the blue mussel, Mytilus edulis

Abstract

Using polymerase chain reaction, cloning and sequencing techniques, a complementary DNA encoding a low molecular mass cellulase (endo‐1,4‐β‐d‐glucanase, EC 3.2.1.4) has been identified in the digestive gland of the marine mussel, Mytilus edulis. It contains a 5′ untranslated region, a 633‐nucleotide ORF encoding a 211 amino‐acid protein, including a 17 amino‐acid signal peptide and a complete 3′ untranslated region. At the C‐terminal end of the purified mature protein, a 13 amino‐acid peptide is lacking in comparison to the protein sequence deduced from the ORF. This peptide is probably removed as a consequence of post‐translational amidation of the C‐terminal glutamine. The endoglucanase genes have been isolated and sequenced from both Swedish and French mussels. The coding parts of these two sequences are identical. Both genes contain two introns, the positions of which are conserved. However the length of the introns are different due to base substitutions, insertions or deletions showing the existence of interspecies length polymorphism. The percentage of similarity for the introns of the two gene sequences is 96.9%. This is the first time a molluscan cellulase is characterized at DNA level. Amino acid sequence‐based classification has revealed that the enzyme belongs to the glycosyl hydrolase family 45 [B. Henrissat (Centre de Recherches sur les Macromolecules Végétales, CNRS, Joseph Fourier Université, Grenoble, France), personal communication]. There is no cellulose binding domain associated with the sequence.

Identification and Characterization of Expansins from Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae)

“…The EG45-like domain found in diverse EXP-related proteins (Kudla et al, 2005;Li et al, 2002;Xu et al, 2001) has multiple cysteine/tryptophan residues and conserved HFD amino acid sequence motif. Non-plant EXPs including nematode EXPs may have evolved independently of plant EXPs leading to the different gene structure.…”

Possibility of direct utilization of seagrass and algae as main food resources by small gastropod, Lacuna decorata, in a subarctic lagoon, Hichirippu, eastern Hokkaido, Japan with stable isotope evidences of carbon and nitrogen

“…However, some invertebrates have been reported to have a cellulase. In particularly, endogenous cellulase genes have been cloned from a common Japanese brackish water clam, Corbicula japonica (Sakamoto et al 2007), abalone (Suzuki et al 2003), and mussel (Xu et al 2001), proving direct digestion of cellulose by those aquatic invertebrates. Three species of estuarine gastropods were also reported to have cellulase activity (Antonio et al 2010).…”

Degradation of Plant-derived Carbohydrates in Wetlands

“…Endogenous cellulases were also found in other insects including Lepidoptera Spodoptera frugiperda and Bombyx mori, Coleoptera Tenebrio molitor and Blattodea Leucophaea maderae Ferreira et al 2001;Cornette et al 2003;Byeon et al 2005). Biochemical detection of endoglucanase has been shown in the Mollusca including mussel Mytilus edulis, abalone Haliotis discus hannai, fresh water snail Ampullaria crossean and the clam Corbicula japonica (Xu et al 2001;Suzuki et al 2003;Wang et al 2003;Sakamoto et al 2007;Guo et al 2008;Rahman et al 2014). However, so far, there are no reports identifying the genetic origin of b-glucosidase in the Mollusca.…”

“…However, the discovery of an endogenous cellulase gene located in the host chromosome of an insect refuted the symbiotic theory (Watanabe et al 1998). Subsequent studies discovered that five out of fourteen families of glycoside hydrolases (GHFs 5,6,45,10 and 9) exist in invertebrates (Smant et al 1998;Xu et al 2001;Suzuki et al 2003;Matthysse et al 2004;Tanimura et al 2013a). In particular, GHF9 was shown to be widely distributed in invertebrates (Davison and Blaxter 2005).…”