Structural Characterization of Parvalbumin from an Antarctic Notothenioid Fish Species

• Main Author: Hendrickson, Jamie Willis
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2005
• Subjects: Fishes; Antarctica; Proteins; Research; Oceanography; Terrestrial and Aquatic Ecology; Antarctic; Antarc*; Icefish
• Online Access: https://digitalcommons.library.umaine.edu/etd/1477; https://digitalcommons.library.umaine.edu/context/etd/article/2503/viewcontent/HendricksonJW2005.pdf

Parvalbumins are proteins that buffer intracellular calcium concentrations and facilitate muscle relaxation. They are important in fish white muscle, which powers burst-speed swimming. Expression of parvalbumin in white muscle of Antarctic fishes is higher than has been observed in temperate water fishes. At respective physiological temperatures, parvalbumins from temperate water and Antarctic fishes exhibit similar calcium dissociation constants. However, calcium dissociation constants for temperate water fish parvalbumins are lower than those from Antarctic fish species across a range of temperatures. This observation suggests that Antarctic fish parvalbumins differ structurally from those of temperate water fish species. This study addressed the hypothesis that Antarctic fish parvalbumins have been selectively modified to conserve function at cold body temperatures. Parvalbumin cDNA was isolated from white muscle of Antarctic icefish Chaenocephalus aceratus, and three distinct parvalbumin mRNA transcripts were identified. One rnRNA transcript is nearly identical to that predicted from amino acid sequence of native parvalbumin from C. aceratus, which was generated by mass spectrometry protein sequencing. This result indicates that C. aceratus white muscle predominantly expresses one parvalbumin rnRNA. Nucleotide sequence of the parvalbumin gene coding region was obtained via RACE, and protein primary structure was deduced. Analysis of inferred amino acid sequence indicates that parvalbumin from C. aceratus white muscle contains 109 amino acids, with a molecular size of 11.5 kDa, similar to parvalbumins from other fishes. Amino acid composition is also similar to other fish parvalbumins. Analysis of parvalbumin amino acid sequence suggests specific modifications in protein primary structure may permit conservation of parvalbumin function at cold temperatures. Comparison of parvalbumin sequence between C. aceratus and other fish species reveals that E-F hand cation-binding domains are highly conserved across ...