Regulation of proline synthesis in osmotic response: Effects of protein synthesis inhibitors

✍ Scribed by Burton, Ronald S.

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 609 KB
• Volume: 259
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402590219

✦ Synopsis

Abstract

Like many euryhaline marine invertebrates, the copepod Tigriopus californicus acclimates to changes in environmental salinity by adjusting intracellular concentrations of free amino acids (FAA). Proline and alanine are the primary contributors to the FAA pool, and previous work has shown that synthesis of the former is specifically induced by hyperosmotic stress. To determine if protein synthesis plays a regulatory role in the accumulation of FAA during hyperosmotic stress, T. californicus were exposed to two protein synthesis inhibitors prior to and during transfer from 50% to 100% seawater. Both inhibitors, cycloheximide and anisomycin, were found to sharply reduce proline synthesis during hyperosmotic stress. By providing ^14^C‐(U)‐L‐glutamate as a proline precursor, evidence was obtained that the ultimate site of action for the inhibitors was in the three‐step pathway between glutamate and proline. This work suggests that hyperosmotic stress induces the synthesis of one or more of the enzymes in the proline biosynthetic pathway or a protein which functions to stimulate the activity of these enzymes.