TABLE 16.
Examples of archaeal Hsp60 proteins (chaperonins) that have been studied experimentally
| Organism | Protein or structured | Length (amino acids)/ mass (kDa)a | Function/structure | Remarks | Reference(s) |
|---|---|---|---|---|---|
| Archaeoglobus fulgidus | ThsA/Cpn-α | 545/59.0 | NRb | Heat shock-induced | 74 |
| ThsB/Cpn-β | 545/59.7 | NR | increase | ||
| Desulforococcus strain SY | HHSP | NR | 140 | ||
| Haloferax volcanii | Cct1 | 560/59.0 | Two ATP-binding sites, including GDGTTc | 163 | |
| Cct2 | 557/59.0 | Two ATP-binding sites, including GDGTT | |||
| Methanococcus jannaschii | Chaperonin | NR/60.0 | ATP-binding site (GDGTT) | Refolding activity | 161 |
| Methanopyrus kandleri | Thermosome | 545/59.5 | ATP-binding site (GDGTT) | NH4+-dependent ATPase activity | 2, 3 |
| Methanococcus thermolithotrophicus | MTTS | 544/NR | ATP-binding site (GDGTT); unique GGX (M,D,S)c repeats in C terminus | ATPase activity; refolding activity; forms filaments; specific nucleotide requirements | 84 |
| Pyrococcus kodakaraensis KOD1 | CpkA | 549/59.2 | ATP-binding site (GDGTT) | Enhances solubility of peptide | 137, 305 |
| CpkB | 546/59.1 | ATP-binding site (GDGTT) | Prevents thermal denaturation; enhances thermostability | ||
| Pyrodictium brockii | ATPase complex | NR/56 and 59 | NR | Heat shock-induced increase | 230 |
| Pyrodictium occultum | TF55/ATPase complex | NR/56 and 59 | NR | Heat shock-induced increase; ATPase activity | 202, 230 |
| Sulfolobus shibatae | TF55-β | 552/59.7 | No conserved ATP-binding site | Heat-shock induced increase; ATPase activity; binds unfolded protein; conformational changes; forms filaments | 141, 234, 280, 307 |
| TF56-α | 560/59.9 | ATP-binding site (GDGTT) | |||
| Sulfolobus solfataricus | α subunit | NR/NR | NR | Associated with aminopeptidase activity; RNA binding; involved in rRNA processing; specific endonuclease activity; refolding activity | 43, 101, 154, 187, 249 |
| β subunit | NR/NR | NR | |||
| Sulfolobus sp. strain 7 | α subunit | 559/60.2 | NR | No ATPase activity; involved in refolding; able to form homo-oligomeric complexes in vitro | 207, 309 |
| β subunit | 552/59.9 | NR | |||
| Thermococcus strain KS-1 | α subunit | 545/59.1 | ATP-binding site (GDGTT), G-Mc motif in C-terminus | ATPase activity; able to form homo-oligomeric complexes in vitro; involved in refolding | 308 |
| β subunit | 548/59.2 | ATP-binding site (GDGTT) | |||
| Thermoplasma acidophilum | α subunit | 545/58.2 | ATP-binding site (GDGTT) | Alternating α and β units; binds unfolded protein; ATPase activity | 65, 153, 216, 289, 290 |
| β subunit | 543/58.5 | ATP-binding site (GDGTT) |
a
Calculated from the deduced amino acid sequence.
b
NR, not reported.
c
Amino acid single-letter symbols.
d
HHSP, hyperthermophilic heat shock protein; MTTS, Methanococcus thermolithotrophicus thermosome.