Abstract: | Late embryogenesis abundant (LEA) proteins are hydrophilic, mostly intrinsically
disordered proteins, which play major roles in desiccation tolerance. In
Arabidopsis thaliana, 51 genes encoding LEA proteins clustered
into nine families have been inventoried. To increase our understanding of the yet
enigmatic functions of these gene families, we report the subcellular location of
each protein. Experimental data highlight the limits of in silico predictions for
analysis of subcellular localization. Thirty-six LEA proteins localized to the
cytosol, with most being able to diffuse into the nucleus. Three proteins were
exclusively localized in plastids or mitochondria, while two others were found dually
targeted to these organelles. Targeting cleavage sites could be determined for five
of these proteins. Three proteins were found to be endoplasmic reticulum (ER) residents, two were vacuolar, and two were
secreted. A single protein was identified in pexophagosomes. While most LEA protein
families have a unique subcellular localization, members of the LEA_4 family are
widely distributed (cytosol, mitochondria, plastid, ER, and pexophagosome) but share the presence of the class A
α-helix motif. They are thus expected to establish interactions with various
cellular membranes under stress conditions. The broad subcellular distribution of LEA
proteins highlights the requirement for each cellular compartment to be provided with
protective mechanisms to cope with desiccation or cold stress. |