The stability of proteins in extreme environments

Adaptation of model proteins from cold to hot environments involves continuous and small adjustments of average parameters related to amino acid composition

“…Several reviews summarized the properties of proteins isolated from thermophiles (Jaenicke and Zavodsky, 1990;Jaenicke, 1991;Adams, 1993;Vieille et al, 1996;Jaenicke and Böhm, 1998;Niehaus et al, 1999;Vieille and Zeikus, 2001;Sterner and Liebl, 2001) and psychrophiles Gerday et al 1997;Sanders et al, 2003;Georlette et al 2004;Siddiqui and Cavicchioli, 2006). Comprehensive studies on crystal structures of thermophilic proteins did not reveal unusual conformations specific to the source type (Petukhov et A c c e p t e d m a n u s c r i p t 5 al., 1997; Facchiano et al, 1998;Karshikoff and Ladenstein, 1998;Szilagyi and Zavodszky, 2000;Kumar et al, 2000).…”

The intrachain disulfide bridge is responsible of the unusual stability properties of novel acylphosphatase from Escherichia coli

“…The reduced activity of EcoAcP might result from a non-optimal alignment of the catalytic residues in the active site or from an increased rigidity of the molecule [16] that does not seem to depend on the presence of the disulfide bridge.…”

“…Instead, EcoAcP does not display any ion pair network on surface, one of the recognised leading features leading to stabilization of hyperthermophilic proteins [19]. It is known that the structural rigidity is often associated to a reduced enzymatic activity [16]. The sequences of EcoAcP and the thermo-resistant SsoAcP display a remarkable identity that is not limited to the region around of the AcP active site signature but spans the whole sequence (Fig.…”

Does the elimination of ion pairs affect the thermal stability of cold shockprotein from the hyperthermophilic bacterium Thermotoga maritima?

“…No general answer has yet been given. Comparisons of proteins from (hyper-)thermophiles and their mesophilic counterparts seem to indicate that any protein investigated so far has evolved its individual strategy [1]. Site-specific mutagenesis has been used successfully to unravel mechanisms of stabilization.…”

“…Since Csps from mesophiles and (hyper-)thermophiles differ only in a small number of amino acid residues, it seems most promising to make use of systematic or random mutagenesis in order to correlate increments of stabilization with specific amino acid substitutions. In this context, the most promising candidates seem to be ion pairs close to the protein surface [1,2].…”