Tobacco mitochondrial small heat shock protein NtHSP24.6 adopts a dimeric configuration and has a broad range of substrates

Abstract

There is a broad range of different small heat shock proteins (sHSPs) that have diverse structural and functional characteristics. To better understand the functional role of mitochondrial sHSP, NtHSP24.6 was expressed in Escherichia coli with a hexahistidine tag and purified. The protein was analyzed by non-denaturing PAGE, chemical cross-linking and size exclusion chromatography and the H6NtHSP24.6 protein was found to form a dimer in solution. The in vitro functional analysis of H6NtHSP24.6 using firefly luciferase and citrate synthase demonstrated that this protein displays typical molecular chaperone activity. When cell lysates of E. coli were heated after the addition of H6NtHSP24.6, a broad range of proteins from 10 to 160 kD in size remained in the soluble state. These results suggest that NtHSP24.6 forms a dimer and can function as a molecular chaperone to protect a diverse range of proteins from thermal aggregation. [BMB reports 2011; 44(12): 816-820]

It takes a dimer to tango: Oligomeric small heat shock proteins dissociate to capture substrate

“…sHsps are characterized by a 90 -amino acid, ␤-sheet-rich ␣-crystallin domain (ACD, or Hsp20 domain, PF00011), flanked by sequences of variable length and composition (N-terminal (NT) sequence; C-terminal (CT) sequence) (11,12). The majority form large oligomers containing 12 to Ͼ40 units, with a dimeric substructure (1,3,5), although there are a few dimeric sHsps, some of which are active chaperones (5,(13)(14)(15). Although vertebrate sHsps assemble principally as polydisperse oligomers, some bacterial, yeast, and plant sHsps are monodisperse.…”

Model Chaperones: Small Heat Shock Proteins from Plants

“…Another plant sHSP, recombinant mitochondrial NtHsp24.6 from tobacco has been reported to be a dimer (Kim et al 2011b ). However, the protein was purifi ed from E. coli using a hexahistidine tag fused to the N-terminus.…”

Functional study of potential sHSPs in Arabidopsis and tomato under environmental stress.

“…This evidence suggests that these mitochondrial proteins have a role in the adaptation of plants to heat stress. To date, the sHSP-M has been investigated in rice [Mani, 2015], pea [Avelange-Macherel, 2015], tobacco [Kim, 2011], tomato [Liu, 1999], Arabidopsis [Waters, 2008a] and maize [Lund, 2001]. However, much about the function of mitochondria-localized sHSPs is still unknown.…”