Identification and Characterization of a Chitin-binding Protein Purified from Coelomic Fluid of the Lugworm Arenicola marina Defining a Novel Protein Sequence Family

Abstract

Background:The immune system of the lugworm depends solely on innate pattern recognition molecules. Results: AML-1 was isolated from the coelomic fluid, cloned and characterized as a pattern recognition receptor that binds chitin. Conclusion: AML-1 is the first polychaete lectin cloned and characterized. Significance: AML-1 represents a novel protein sequence family that may give rise to a new protein structure.

Transcriptomic profiling of immune‐associated molecules in the coelomocytes of lugworm Arenicola marina (Linnaeus, 1758)

“…We identified a new variant of AML‐1, AML‐1C, in the transcriptome of A. marina coelomocytes. Its amino‐acid sequence is identical to that previously described in AML‐1A and AML‐1B (Vitashenkova et al, 2012) by 95% and 91%, respectively. In addition, we described three novel genes encoding AML‐1‐like proteins with the C‐terminal u‐domain.…”

“…Another chitin‐binding lectin, the only one experimentally characterized in A. marina coelomocytes and coelomic fluid, is AML‐1 (Vitashenkova et al, 2012). It represents a family of calcium‐independent secreted oligomeric lectins bearing a novel C‐terminal unnamed domain (u‐domain).…”

“…Apart from A. marina , this domain has been found only in some uncharacterized proteins of anthozoan cnidarians (BlastP nr: Acropora digitifera , Stylophora pistillata , Orbicella faveolate , Nematostella vectensis , etc.). AML‐1 demonstrates features of an acetyl group‐specific PRR (Vitashenkova et al, 2012).…”

“…The diversity and the abundance of microorganisms coexisting with A. marina is fairly high; it is therefore obvious that the lugworm should be well equipped to resist microbial and other pathogens, and this is indeed reflected in its molecular immune-related arsenal. It has been shown that A. marina possesses the well-characterized antimicrobial peptides (AMPs) arenicins (Lee et al, 2007;Maltseva et al, 2014;Ovchinnikova et al, 2004Ovchinnikova et al, , 2007Sandvang et al, 2008) and pattern-recognition receptor (PRR) of lectin nature AML-1 (Vitashenkova et al, 2012).…”

“…The diversity and the abundance of microorganisms coexisting with A. marina is fairly high; it is therefore obvious that the lugworm should be well equipped to resist microbial and other pathogens, and this is indeed reflected in its molecular immune‐related arsenal. It has been shown that A. marina possesses the well‐characterized antimicrobial peptides (AMPs) arenicins (Lee et al, 2007; Maltseva et al, 2014; Ovchinnikova et al, 2004, 2007; Sandvang et al, 2008) and pattern‐recognition receptor (PRR) of lectin nature AML‐1 (Vitashenkova et al, 2012). Another side of A. marina adaptation to anoxic environment is a highly effective oxygen‐carrying extracellular hemoglobin (Hb), a promising candidate for a blood substitute, which is also involved in innate immunity (Chabasse et al, 2006; Jernshøj et al, 2013).…”