Protein stability in Artemia embryos during prolonged anoxia.
Encysted embryos (cysts) of the brine shrimp, Artemia franciscana, are arguably the most stress-resistant of all animal life-history stages. One of their many adaptations is the ability to tolerate anoxia for periods of years, while fully hydrated and at physiological temperatures. Previous work indicated that the overall metabolism of anoxic embryos is brought to a reversible standstill, including the transduction of free energy and the turnover of macromolecules. But the issue of protein stability at the level of tertiary and quaternary structure was not examined. Here I provide evidence that the great majority of proteins do not irreversibly lose their native conformation during years of anoxia, despite the absence of detectable protein turnover. Although a modest degree of protein denaturation and aggregation occurs, that is quickly reversed by a brief post-anoxic aerobic incubation. I consider how such extraordinary stability is achieved and suggest that at least part of the answer involves massive amounts of a small heat shock protein (p26) that acts as a molecular chaperone, the function of which does not appear to require ribonucleoside di- or tri-phosphates.
Clegg
James S
JS
Section of Molecular & Cellular Biology, and Bodega Marine Laboratory, University of California (Davis), Bodega Bay, California 94923, USA. jsclegg@ucdavis.edu
D000818:Animals; D001156:Artemia / Q000196:embryology* / Q000378:metabolism; D060829:Arthropod Proteins; D002250:Carbon Radioisotopes; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology; D015687:Cell Hypoxia; D004591:Electrophoresis, Polyacrylamide Gel; D004625:Embryo, Nonmammalian / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology; D033862:Iron-Binding Proteins; D018832:Molecular Chaperones / Q000378:metabolism / Q000502:physiology; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins
D060829:Arthropod Proteins; D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D033862:Iron-Binding Proteins; D018832:Molecular Chaperones; D011506:Proteins; D016601:RNA-Binding Proteins; C490888:artemin protein, brine shrimp; C107632:p26 chaperone protein, Artemia franciscana