Late embryogenesis abundant proteins
From Wikipedia, the free encyclopedia
Late embryogenesis abundant proteins (LEA proteins) are proteins in plants, some bacteria, and invertebrates that protect against protein aggregation due to desiccation or osmotic stresses associated with low temperature.[1][2][3] LEA proteins were initially discovered accumulating late in embryogenesis of cotton seeds.[4] Originally noticed due to its abundance in seeds and pollens,[2] LEA proteins have been found to protect against desiccation, cold, or high salinity in a variety of organisms, including the bacterium Deinococcus radiodurans, nematode Caenorhabditis elegans, Artemia (brine shrimp), and rotifers.[5][6]
Function
LEA proteins function by mechanisms which are distinct from those displayed by heat shock molecular chaperones.[1] Although the causes of LEA protein induction have not yet been determined, conformational changes in transcription factors or integral membrane proteins due to water loss have been suggested.[7] LEA proteins are particularly protective of mitochondrial membranes against dehydration damage.[8]
Types
LEA proteins are grouped by sequence similarity into 5 or 7 major groups, with 9 to 14 subgroups. There is also a simplistic scheme that groups by origin, i.e. plant, bacterial, and animal.[9] The groups are:[10][11]
| Pfam | Battaglia | Bray | Dure | Bies-Ethève | Names |
|---|---|---|---|---|---|
| Dehydrin (PF00257) | 2 | 2 | D-11 | 2 | Dehydrin, RAB |
| SMP (PF04927) | 5A | 6 | D-34 | 5 | PAP140 |
| LEA_1 (PF03760) | 4A | 4 | N/a | 4 | LE25_LYCES |
| 4B | D-113 | PAP260, PAP051 | |||
| LEA_2 (PF03168) | 5C | N/a | D-95 | 7 | LEA14, WHy domain[9] |
| LEA_3 (PF03242) | 5B | N/a | D-73 | 6 | AtD121, Sag21, lea5 |
| LEA_4 (PF02987) | 3A | 3 | D-7 | 3 | ECP63, PAP240, PM27 |
| 3B | 5→3 | D-29 | D-29 | ||
| LEA_5 (PF00477) | 1 | 1 | D-19 | 1 | Em1, Em6 |
| LEA_6 (PF10714) | 6 | N/a | N/a | 8 | LEA18 |
| AWA_WDS (PF02496) | 7 | N/a | N/a | N/a | ASR |
One reason there are so many different families is that the LEA proteins were originally noticed by their common compositional and biophysical features (hydrophilic, high glycine), not by a united ancestry. There are many additional families that also share these features but they are not as common in plants.[10] According to LEAPdb, the Pfam classification is the most comprehensive.[11]
