Identification and characterization of an isoform antifreeze protein from the antarctic marine diatom, chaetoceros neogracile and suggestion of the core region

Minjae Kim, Yunho Gwak, Woongsic Jung, Eon Seon Jin

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Antifreeze proteins (AFPs) protecting the cells against freezing are produced in response to extremely low temperatures in diverse psychrophilic organisms, and they are encoded by multiple gene families. The AFP of Antarctic marine diatom Chaetoceros neogracile is reported in our previous research, but like other microalgae, was considered to probably have additional genes coding AFPs. In this paper, we reported the cloning and characterization of additional AFP gene from C. neogracile (Cn-isoAFP). Cn-isoAFP protein is 74.6% identical to the previously reported Cn-AFP. The promoter sequence of Cn-isoAFP contains environmental stress responsive elements for cold, thermal, and high light conditions. Cn-isoAFP transcription levels increased dramatically when cells were exposed to freezing (−20 C), thermal (10 C), or high light (600 µmol photon m2 s1) stresses. The thermal hysteresis (TH) activity of recombinant Cn-isoAFP was 0.8 C at a protein concentration of 5 mg/mL. Results from homology modeling and TH activity analysis of site-directed mutant proteins elucidated AFP mechanism to be a result of flatness of B-face maintained via hydrophobic interactions.

Original languageEnglish
Article number318
JournalMarine drugs
Volume15
Issue number10
DOIs
StatePublished - 2017 Oct

Keywords

  • 3D-structure modeling
  • Antarctic marine diatom
  • Antifreeze activity
  • Chaetoceros neogracile
  • Isoform antifreeze protein

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