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Target enzymes are stabilized by AfrLEA6 and a gain of α-helix coincides with protection by a group 3 LEA protein during incremental drying.

Authors
  • LeBlanc, Blase M1
  • Hand, Steven C2
  • 1 Division of Cellular Developmental and Integrative Biology, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA. Electronic address: [email protected]
  • 2 Division of Cellular Developmental and Integrative Biology, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA; Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA. Electronic address: [email protected]
Type
Published Article
Journal
Biochimica et biophysica acta. Proteins and proteomics
Publication Date
Jun 01, 2021
Volume
1869
Issue
6
Pages
140642–140642
Identifiers
DOI: 10.1016/j.bbapap.2021.140642
PMID: 33647452
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Anhydrobiotic organisms accumulate late embryogenesis abundant (LEA) proteins, a family of intrinsically disordered proteins (IDPs) reported to improve cellular tolerance to water stress. Here we show that AfrLEA6, a Group 6 LEA protein only recently discovered in animals, protects lactate dehydrogenase (LDH), citrate synthase (CS) and phosphofructokinase (PFK) against damage during desiccation. In some cases, protection is enhanced by trehalose, a naturally-occurring protective solute. An open question is whether gain of secondary structure by LEA proteins during drying is a prerequisite for this stabilizing function. We used incremental drying (equilibration to a series of relative humidities, RH) to test the ability of AfrLEA2, a Group 3 LEA protein, to protect desiccation-sensitive PFK. AfrLEA2 was chosen due to its exceptional ability to protect PFK. In parallel, circular dichroism (CD) spectra were obtained for AfrLEA2 across the identical range of relative water contents. Protection of PFK by AfrLEA2, above that observed with trehalose and BSA, coincides with simultaneous gain of α-helix in AfrLEA2. At 100% RH, the CD spectrum for AfrLEA2 is typical of random coil, while at decreasing RH, the spectrum shows higher ellipticity at 191 nm and minima at 208 and 220 nm, diagnostic of α-helix. This study provides experimental evidence linking the gain of α-helix with stabilization of a target protein across a graded series of hydration states. Mechanistically, it is intriguing that certain other functions of these IDPs, like preventing aggregation of target proteins, can occur in fully hydrated cells and apparently do not require gain of α-helix. Copyright © 2021 Elsevier B.V. All rights reserved.

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