Proteomic analysis of heat-stable proteins in Escherichia coli

Abstract

Some proteins of E. coli are stable at temperatures significantly higher than 49 o C, the maximum temperature at which the organism can grow. The heat stability of such proteins would be a property which is inherent to their structures, or it might be acquired by evolution for their specialized functions. In this study, we describe the identification of 17 heat-stable proteins from E. coli. Approximately one-third of these proteins were recognized as having functions in the protection of other proteins against denaturation. These included chaperonin (GroEL and GroES), molecular chaperones (DnaK and FkpA) and peptidyl prolyl isomerases (trigger factor and FkpA). Another common feature was that five of these proteins (GroEL, GroES, Ahpc, RibH and ferritin) have been shown to form a macromolecular structure. These results indicated that the heat stability of certain proteins may have evolved for their specialized functions, allowing them to cope with harsh environments, including high temperatures. [BMB reports 2008; 41(2): 108-111]

Escherichia coli transcription termination factor NusA: heat-induced oligomerization and chaperone activity

“…1c). These results indicate that similar to other heat-stable proteins20, NusA can form stable HMW oligomers.…”

“…The high temperature stability of E. coli NusA under physiological conditions has previously been demonstrated20. Herein, we overexpressed and purified E. coli NusA.…”

“…Protein oligomerization has been shown to enhance the thermostability of thermophilic archaeal proteins41. In mesophilic E. coli , a large proportion of heat stable proteins can also form high oligomers20, implying that oligomerization could also contribute to protein stability in mesophiles. As one of these heat stable proteins, the E. coli NusA, which exists in monomeric form in its native state8, was found in this study to form HMW oligomers in vitro and in the cells of the NusA-overexpressing strain.…”

Aspartyl aminopeptidase of Schizosaccharomyces pombe has a molecular chaperone function

“…Some proteins including heat shock protein 70 Homolog precursor (Hsp 70, NP_592867.1, SPAC1F5.06), alcohol dehydrogenase I (NP_588244, SPCC13B11.01), thioredoxin peroxidase (NP_588430, SPCC576.03c) and putative aspartyl aminopeptidase (AAP, O36014, NP_594745, SPAC4-F10.02) were well matched with S. pombe proteins (data not shown). In E. coli, heat stable proteins including chaperone Hsp70 (Dnak), histidine-binding periplasmic protein (HBP) and hypothetical protein YjgF were reported (19). AAP screened as a heat-stable protein showed sequence Homology to aspartyl aminopeptidase purified from rabbit brain cytosol and S. cerevisiae.…”

A role for the Parkinson’s disease protein DJ-1 as a chaperone and antioxidant in the anhydrobiotic nematode Panagrolaimus superbus

“…High thermal stability values are characteristic of molecular chaperones (Sastry et al 2002;Warner et al 2004;Kwon et al 2008). We examined the thermal stability of the helix domains of native PsuDJ-1.1 using CD spectral analysis by monitoring the change in ellipticity (Δε) of the helix domains at 222 nm as a function of temperature.…”