Isoform-specific responses of metallothioneins in a marine pollution biomonitor, the green-lipped mussel Perna viridis, towards different stress stimulations.
Metallothioneins (MTs) are commonly used as biomarker for metal pollution assessment in marine ecosystems. Using integrated genomic and proteomic analyses, this study characterized two types of MT isoform in the digestive gland of a common biomonitor, the green-lipped mussel Perna viridis, towards the challenges of a metal (cadmium; Cd) and a non-metal oxidant (hydrogen peroxide; H2 O2 ) respectively. The two isoforms differed in their deduced protein sequences, with 73 amino acids for MT10-I and 72 for MT10-II (a novel type), but both consisted of a high percentage (27.4 to 29.2%) of cysteine. Two-dimensional gel and Western blot showed that the MT proteins were present in multiple isoform spots, and they were further validated to be MT10-I and MT10-II using MS analysis coupled with unrestricted modifications searching. Expression of mRNA revealed that MT10-I responded promptly to Cd but had a lagged induction to H2 O2 treatments, while MT10-II was exclusively induced by Cd treatment over the course of exposure. Expression of the MT proteins also showed a delayed response to H2 O2 , compared to Cd treatments. This study uncovered the potential different functional roles of various MTs isoforms in P. viridis and thus advances the resolution of using MTs as biomarkers in future applications.
The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong, P. R. China.
Priscilla T Y
PT
Leung
T J
TJ
Park
Yu
Y
Wang
C M
CM
Che
Kenneth M Y
KM
Leung
D000595:Amino Acid Sequence; D000818:Animals; D002104:Cadmium / Q000633:toxicity; D004064:Digestive System / Q000737:chemistry; D004784:Environmental Monitoring; D006861:Hydrogen Peroxide / Q000633:toxicity; D008668:Metallothionein / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D049883:Perna / Q000378:metabolism* / Q000502:physiology; D020033:Protein Isoforms / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D016415:Sequence Alignment; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology*
D020033:Protein Isoforms; D002104:Cadmium; D008668:Metallothionein; D006861:Hydrogen Peroxide
Animal proteomics; Cadmium; Hydrogen peroxide; Metallothionein isoform; Mussel; Perna viridis