Meeting Abstract
P1.116 Friday, Jan. 4 Improved Tolerance to Salt and Water Stress in Drosophila melanogaster Cells Conferred by Late Embryogenesis Abundant Protein MARUNDE, M*; SAMARAJEEWA, DA; NGUYEN, M; HAND, SC; MENZE, MA; Eastern Illinois University; Louisiana State University mmenze@eiu.edu
Mechanisms that govern anhydrobiosis (‘life without water’) involve the accumulation of highly hydrophilic macromolecules, such as late embryogenesis abundant (LEA) proteins. We designed primers based on NCBI sequence ACX81198 (Warner et al., 2009) to amplify cDNA from Artemia franciscana and a mitochondrial localized Group 1 LEA protein comprised of 197 amino-acid (LEA1.3) was stably expressed in Drosophila melanogaster cells (Kc167). In the presence of mixed substrates, oxygen consumption was statistically identical for permeabilized Kc167 control and Kc167-AfLEA1.3 cells except in the uncoupled state. Acute titrations with NaCl up to 500 mM led to successive drops in oxygen flux, which was significantly ameliorated by 18% in Kc167-AfLEA1.3 cells compared to Kc167 controls. Expression of AfLEA1.3 did not improve the decrease in viability in response to 1h heat shock at 42 ˚C (35 ± 4.6) of Kc167-AfLEA1.3 cells showed compromised membranes 24h after heat shock vs. 32.4 ± 4.0 of control cells, n = 12; ±SD, p>0.05), but AfLEA1.3 expressing cells survived desiccation by air drying to lower final moisture contents than did control Kc167 cells (0.36 gH2O/gDW vs.1.02 gH2O/gDW). Thus, AfLEA1.3 exerts a protective influence on mitochondrial function and increases viability of Kc167 cells during water stress. Notably, in some cases where we observed protection, LEA proteins were no doubt fully-hydrated and intrinsically disordered, because folding into α-helix occurs only during severe desiccation. Consequently, the folded conformation of LEA proteins is not always required to confer protection against water stress (NSF-IOS-0920254, CFR-EIU).
