Small heat shock protein of Methanococcus jannaschii, a hyperthermophile.
Small heat shock proteins (sHSPs) belong to a family of 12- to 43-kDa proteins that are ubiquitous and are conserved in amino acid sequence among all organisms. A sHSP homologue of Methanococcus jannaschii, a hyperthermophilic Archaeon, forms a homogeneous multimer comprised of 24 monomers with a molecular mass of 400 kDa in contrast to other sHSPs that show heterogeneous oligomeric complexes. Electron microscopy analysis revealed a spherically shaped oligomeric structure approximately 15-20 nm in diameter. The protein confers thermal protection of other proteins in vitro as found in other sHSPs. Escherichia coli cell extracts containing the protein were protected from heat-denatured precipitation when heated up to 100 degreesC, whereas extracts from cells not expressing the protein were heat-sensitive at 60 degreesC. Similar results were obtained when purified sHSP protein was added to an E. coli cell lysate. The protein also prevented the aggregation of two purified proteins: single-chain monellin (SCM) at 80 degreesC and citrate synthase at 40 degreesC.
Physical Biosciences Division of Lawrence Berkeley, National Laboratory and Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-5230, USA. r_kim@1bl.gov
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D000818:Animals; D002850:Chromatography, Gel; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D017017:Methanococcus / Q000378:metabolism*; D008854:Microscopy, Electron; D010940:Plant Proteins / Q000378:metabolism; D011489:Protein Denaturation; D013552:Swine
D006360:Heat-Shock Proteins; D010940:Plant Proteins; C002541:monellin protein, Dioscoreophyllum cumminsii; D002950:Citrate (si)-Synthase