Hsp14 (Saci_1665, Q4J8A6) - Research Notes

Overview

Hsp14 is a small heat shock protein (sHSP) of the alpha-crystallin/Hsp20 family from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. It is 126 amino acids (14.3 kDa). S. acidocaldarius grows optimally at 75-80 degrees C and pH 2-3, and has a minimalist chaperone repertoire: Hsp14, Hsp20, and Hsp60 (a group II chaperonin/thermosome). Notably, Hsp70 is absent from this organism PMID:34637594.

Key Publications

PMID:34637594 - Roy et al. (2022) FEBS J

"Archaeal Hsp14 drives substrate shuttling between small heat shock proteins and thermosome"

Key findings:
- Hsp14 dimer is the active form; forms oligomeric storage form at higher temperature PMID:34637594
- Rapid subunit exchange between dimeric states; rate increases with temperature PMID:34637594
- Forms hetero-oligomers with Hsp20 at 50-70 degrees C via subunit exchange PMID:34637594
- Direct physical interaction between Hsp14 and Hsp60 (thermosome), enthalpy-driven PMID:34637594
- Hsp14 transfers sHsp-captured substrate proteins to Hsp60 for refolding PMID:34637594
- Fills the substrate transfer role normally played by Hsp70 in other organisms PMID:34637594

PMID:37516156 - Bhowmick et al. (2023) Res Microbiol

"Heat shock response in Sulfolobus acidocaldarius and first implications for cross-stress adaptation"

Key findings:
- hsp14 and hsp20 play crucial roles in the majority of stress conditions PMID:37516156
- Upregulated under heat shock (92 degrees C), oxidative stress, and nutrient stress PMID:37516156

PMID:32562000 - Baes et al. (2020) Extremophiles

"Defining heat shock response for the thermoacidophilic model crenarchaeon Sulfolobus acidocaldarius"

Key findings:
- Dynamic increase in mRNA levels of all relevant heat shock proteins upon heat shock PMID:32562000
- S. acidocaldarius does not seem better equipped to handle sudden supra-optimal temperature stress than mesophilic organisms PMID:32562000

Molecular Functions

  1. Unfolded protein binding (GO:0051082) - Hsp14 binds aggregating/unfolded substrate proteins PMID:34637594
  2. Unfolded protein carrier activity (GO:0140309) - Hsp14 shuttles captured unfolded substrates from sHSPs to the thermosome (Hsp60) for ATP-dependent refolding PMID:34637594. This is the most distinctive function.
  3. Protein-folding chaperone binding (GO:0051087) - Direct physical interaction with Hsp60 (thermosome) PMID:34637594

Biological Processes

  1. Response to heat (GO:0009408) - Upregulated under heat shock [PMID:32562000, PMID:37516156]
  2. Protein folding (GO:0006457) - Participates in the sHSP-to-thermosome protein folding pathway PMID:34637594

Cellular Component

  1. Cytoplasm (GO:0005737) - sHSPs are cytoplasmic proteins

Domain Architecture