Characterization of an Atypical Metalloproteinase Inhibitors Like Protein (Sbp8-1) From Scallop Byssus

Abstract

Adhesion is a vital physiological process for many marine molluscs, including the mussel and scallop, and therefore it is important to characterize the proteins involved in these adhesives. Although several mussel byssal proteins were identified and characterized, the study for scallop byssal proteins remains scarce. Our previous study identified two foot-specific proteins (Sbp7, Sbp8-1), which were annotated as the tissue inhibitors of metalloproteinases (TIMPs). Evolutionary analysis suggests that the TIMP genes of Chlamys farreri had gone through multiple gene duplications during evolution, and their potential functional roles in foot may have an ancient evolutionary origin. Focusing on the Sbp8-1, the sequence alignment and biochemical analyses suggest that Sbp8-1 is an atypical TIMP. One significant feature is the presence of two extra free Cys residues at its C-terminus, which causes the Sbp8-1 polymerization. Considering the fact that the no inhibitory activity was observed and it is mainly distributed in byssal thread and plaque, we proposed that this atypical Sbp8-1 may play as the cross-linker in scallop byssus. This study facilitates not only the understanding of scallop byssus assembly, also provides the inspiration of water-resistant materials design.

The discovered chimeric protein plays the cohesive role to maintain scallop byssal root structural integrity

“…However, the understanding of scallop byssus is still limited. Our previous study 10 – 12 demonstrated that the protein composition of scallop byssus is intriguing as well. Therefore, it is very interesting and important to dissect the key scallop byssal proteins.…”

Decoding the byssus fabrication by spatiotemporal secretome analysis of scallop foot

“…Biochemical analyses and protein polymerization assays implied the potential cross-linker role of the most abundant metalloproteinase inhibitor (CF9441.24, e.g. Sbp8-1, Table S5 ) [20] . Furthermore, another 104 BRPs were classified into group 3, 28.7% of which were molluscan specific genes (ps level ≥ 9, Table S3 ).…”

“…Unlike the permanent adhesion of sessile bivalves (e.g., mussels), scallop remains the ability to discard its byssus instantly under certain adverse conditions, and to reattach to new substrates by rapid secretion of new byssus, which has been proposed as a key biological characteristic for its successful adaptation to various habitats [12] , [17] . Moreover, according to our previous study on Zhikong scallop Chlamys farreri (Jones et Preston, 1904) [17] , [18] , scallops can secrete more abundant byssus than mussels and possess distinct protein composition and unusual assembly mechanisms [17] , [19] , [20] , [21] . The unique adhesive characteristics of scallop byssus make it a valuable biological model to study the dynamic adhesive secretomic process of byssal detachment and reattachment.…”

In Silico Analysis of Pacific Oyster (Crassostrea gigas) Transcriptome over Developmental Stages Reveals Candidate Genes for Larval Settlement

“…The sequence CGI_10005578 (EKC25384 | hypothetical protein) was annotated with Gene Ontology indicating a metalloendoproteinase inhibitor molecular function. Recently, a protein with a similar function was identified in the foot and byssus of Chlamys farreri [12,49]. In this species, the protein Sbp8-1, which was described as an atypical metalloproteinase inhibitor, is a component of the byssus that is probably involved in the binding between the different byssal proteins.…”