A molecular mechanism for membrane chaperoning by a late embryogenesis abundant protein [article]

Xiao-Han Li, Conny W.H. Yu, Natalia Gomez-Navarro, Viktoriya Stancheva, Hongni Zhu, Cristina Guibao, Boer Xie, Andal Murthy, Michael Wozny, Benjamin Leslie, Marcin Kaminski, Ketan Malhotra (+10 others)
2022 bioRxiv   pre-print
Environmental stress can result in substantial damage to proteins, membranes, and genetic material, impacting organismal survival. Stress tolerance can be conferred by intrinsically disordered proteins (IDPs) that lack stable tertiary structure. IDPs from the large family of late embryogenesis abundant (LEA) proteins confer a fitness advantage when heterologously expressed. Such protection suggests a general molecular function leading to stress tolerance, although the mechanisms remain unclear.
more » ... Here, we report that a tardigrade LEA protein that confers stress tolerance in yeast acts as a molecular chaperone for the mitochondrial membrane. This protein, named HeLEA1, localizes to the mitochondrial matrix, and harbors conserved LEA sequence motifs that undergo dynamic disorder-to-helical transition upon binding to negatively charged membranes. Yeast expressing HeLEA1 show increased mitochondrial membrane fluidity, increased membrane potential, and enhanced tolerance to hyperosmotic stress under non-fermentative growth without significantly altering mitochondrial lipid composition or triggering a generic stress response. We demonstrate that membrane binding ameliorates excess surface tension, possibly by stabilizing lipid packing defects. Evolutionary analysis suggests that HeLEA1 homologs localize to different membrane-bound organelles and share similar sequence and biophysical features. We suggest that membrane chaperoning by LEA proteins represents a general biophysical solution that can operate across the domains of life.
doi:10.1101/2022.07.29.502075 fatcat:pygg42xhhzhedh547bctye3lgi