Metallothionein CgMTIII is involved in zinc binding and accumulation in the Pacific oyster Crassostrea gigas

Xiang Li¹, Ning Kong², Wentong Hao¹, Lixin Feng¹, Lingling Wang³, Linsheng Song⁴

Affiliations

¹ Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China.
² Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China. Electronic address: kongning@dlou.edu.cn.
³ Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Functional Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China.
⁴ Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Functional Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian 116023, China. Electronic address: lshsong@dlou.edu.cn.

PMID: 40651624
DOI: 10.1016/j.cbpb.2025.111128

Abstract

Metallothioneins (MTs) are a family of small, metal-binding proteins that play a pivotal role in metal storage and detoxification. The Pacific oyster Crassostrea gigas is known for its exceptionally high zinc content, and investigating the role of MTs in oyster zinc metabolism will help elucidate the mechanisms underlying its zinc accumulation. In this study, a MT homolog CgMTIII was cloned from C. gigas to investigate its function in zinc binding and accumulation. The transcripts of CgMTIII were distributed in all examined oyster tissues including gill, mantle, adductor muscle, hepatopancreas, gonad, labial palp and haemocytes, with the highest expression in the gill and the lowest in the haemocytes. Immobilized metal ion affinity chromatography (IMAC) demonstrated that the recombinant CgMTIII protein exhibited high retention on the zinc-charged column, confirming its zinc-binding activity. Overexpression of CgMTIII in HEK293T cells led to a 2.34-fold increase in intracellular zinc content after 24 h of exposure to 100 μM zinc, compared to the control group. Moreover, knockdown of CgMTIII through RNA interference resulted in a 24% reduction in zinc content in the gill tissue of oysters. Collectively, CgMTIII exhibited zinc-binding activity and contributed significantly to zinc accumulation in C. gigas. These findings deepen our understanding of the zinc-enrichment mechanism in oysters and provide a theoretical foundation for breeding high‑zinc oyster varieties.

Keywords: Crassostrea gigas; Metallothionein; Zinc accumulation; Zinc binding.

Comp Biochem Physiol B Biochem Mol Biol. 2025 Aug-Sep:279:111128.doi: 10.1016/j.cbpb.2025.111128. Epub 2025 Jul 10.

Metallothionein CgMTIII is involved in zinc binding and accumulation in the Pacific oyster Crassostrea gigas

Abstract

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