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.
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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