Reversible suppression of protein synthesis in concert with polysome disaggregation during anoxia exposure in Littorina littorea.

Abstract

Many marine invertebrates can live without oxygen for long periods of time, a capacity that is facilitated by the ability to suppress metabolic rate in anoxia to a value that is typically less than 10% of the normal aerobic rate. The present study demonstrates that a reduction in the rate of protein synthesis is one factor in the overall anoxia-induced metabolic suppression in the marine snail, Littorina littorea. The rate of [3H]leucine incorporation into newly translated protein in hepatopancreas isolated from 48 h anoxic snails was determined to be 49% relative to normoxic controls. However, protein concentration in hepatopancreas did not change during anoxia, suggesting a coordinated suppression of net protein turnover. Analysis of hepatopancreas samples from snails exposed to 24-72 h anoxia showed a gradual disaggregation of polysomes into monosomes. A re-aggregation of monosomes into polysomes was observed after 3 h of aerobic recovery. Analysis of fractions from the ribosome profile using radiolabeled probe to detect alpha-tubulin transcripts confirmed a general decrease in protein translation during anoxia exposure (transcript association with polysomes decreased) with a reversal during aerobic recovery. Western blotting of hepatopancreas samples from normoxic, 24 h anoxic, and 1 h aerobic recovered snails demonstrated that eIF-2alpha is substantially phosphorylated during anoxia exposure and dephosphorylated during normoxia and aerobic recovery, suggesting a decrease in translation initiation during anoxia exposure. These results suggest that metabolic suppression during anoxia exposure in L. littorea involves a decrease in protein translation.

• Authors: Kevin Larade, Kenneth B Storey
• Journal: Molecular and cellular biochemistry (Mol Cell Biochem) Vol. 232 Issue 1-2 Pg. 121-7 (Mar 2002) ISSN: 0300-8177 [Print] Netherlands
• PMID: 12030368 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Eukaryotic Initiation Factor-2
• Proteins
• RNA, Messenger
• Tubulin
• Oxygen

Topics

• Animals
• Blotting, Western
• Electrophoresis, Gel, Two-Dimensional
• Eukaryotic Initiation Factor-2 (analysis)
• Hypoxia (metabolism)
• Mollusca (chemistry, drug effects, metabolism)
• Oxygen (pharmacology)
• Polyribosomes (drug effects, metabolism)
• Protein Biosynthesis (drug effects)
• Proteins (analysis)
• RNA, Messenger (genetics, metabolism)
• Time Factors
• Tubulin (biosynthesis, genetics)