Meeting Abstract
Sirtuins are NAD-dependent deacylases, which change the activity of proteins by removing acyl groups that are linked to energy metabolism, e.g., acetyl-CoA. While their general effect on the proteome is well characterized, their specific role during the response to heat and hypoxia stress is not, neither is the interspecific variation that underlies differences in stress tolerance. We investigated the proteomic changes in gill tissue of Mytilus trossulus, which is native to the Pacific coast of North America, and M. galloprovincialis, a more heat-tolerant invader from the Mediterranean, which replaced the native in the southern part of its range. Using sirtuin inhibitors, we identified differences in how sirtuins affect molecular chaperones, oxidative stress proteins, metabolic enzymes, cytoskeletal and signaling proteins in the two congeners. Interactions between sirtuin inhibition and changes in the abundance of proteins of β-oxidation and oxidative stress in M. trossulus, suggest a greater role of sirtuins in shifting metabolism to reduce the production of reactive oxygen species near thermal limits. Furthermore, sirtuin inhibition affected RNA-binding proteins initiating and inhibiting translation in M. galloprovincialis and in M. trossulus, respectively. While both species responded to hypoxia with increases in several molecular chaperones and proteins involved in protein degradation, M. trossulus showed a unique increase in small heat-shock proteins. M. galloprovincialis showed a tiered response to oxidative stress under hypoxia, while the response of M. trossulus was muted. It is likely that these interspecific differences in the effects of sirtuins contribute to setting stress tolerance limits (funded by NSF IOS-0717087 and PRFB DBI-1401357).
