Cold adaption of enzymes: Structural comparison between salmon and bovine trypsins

Smalås, Arne O.; Heimstad, Eldbjørg Sofie; Hordvik, Asbjørn; Willassen, Nils Peder; Male, Rune

doi:10.1002/prot.340200205

Cited by 143 publications

(133 citation statements)

References 50 publications

(10 reference statements)

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“…Although only one crystal structure from a psychrophilic enzyme is available ( [50], N. Aghajari and R. Haser, personal communication) in addition to the salmon trypsin [51] and elastase [52] structures, molecular modelling was extremely useful for preliminary structural analyses of cold-adapted enzymes. Structure prediction by homology modelling has recently reached sufficient level of reliability [53,54] to allow close inspection of the psychrophilic enzyme conformation, keeping in mind the limit of confidence of such models.…”

Section: Reviews the Active Site Of Psychrophilic Enzymesmentioning

confidence: 99%

“…In the specific case of psychrophilic enzymes, there is however no direct experimental demonstration of such relationship. The crystallographic B-temperature factors (which are a function of individual atom mobility) of the recently crystallized h-amylase from the Antarctic psychrophile A. haloplanctis (N. Aghajari and R. Haser, personal communication) and of trypsin from the cold-adapted North Atlantic salmon [51] fail to reveal significant difference when compared with X-ray structures of mesophilic homologues. However, constraints imposed by the crystal packing of the molecules and intermolecular contacts can obscure possible differences occurring in solution.…”

Section: Flexibility-activity Relationshipmentioning

confidence: 99%

“…In addition to the above mentioned crystal structures [50,51,52] models of psychrophilic enzymes such as bacterial subtilisin [59], h-amylase [45], triosephosphate isomerase [60], lipase [61], i-lactamase [48] or fish trypsin [62] and elastase [63] reveal that only subtle modifications of their conformation can be related to the low stability (see also [64,65]). Electrostatic weak interactions and the hydrophobic effect make a lower contribution to the global energy of stabilization of the native state whereas destabilizing forces mainly favour the conformational entropy of the unfolded state.…”

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

“…The individual contribution of Hbonds to protein stability is weak but the large number of these interactions in protein structures makes them a predominant factor of the folded state conformation [68]. The crystal structures of salmon and bovine trypsins [51] provided evidence that the disappearance of several H-bonds in the cold-adapted enzyme is responsible for loose contacts between the two i-barrel domains of the protein close to the catalytic residues, and between the C-terminal helix and the N-terminal domain. The total number of polar hydrogen-forming residues (Ser, Thr, Asn and Gln) is also lower in digestive enzymes from cold-adapted fish [69,70].…”

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

“…Attempts to evaluate this effect on the basis of structure have been performed, using the hydrophobic index of individual amino acids forming the protein core, or using hydrophobic cluster analysis. Numerous psychrophilic enzymes display substitutions within the hydrophobic core clusters that are accompanied by a sharp decrease of the hydrophobicity index when compared with mesophilic homologues [45,48,51,62]. Entropic factors.…”

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

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Psychrophilic enzymes: molecular basis of cold adaptation

Feller

Gerday

1997

CMLS, Cell. mol. life sci.

371

233

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Abstract. Psychrophilic organisms have successfully provides enhanced abilities to undergo conformational colonized polar and alpine regions and are able to grow changes during catalysis. Thermal instability of coldefficiently at sub-zero temperatures. At the enzymatic adapted enzymes is therefore regarded as a consequence level, such organisms have to cope with the reduction of of their conformational flexibility. A survey of the psychrophilic enzymes studied so far reveals only minor chemical reaction rates induced by low temperatures in alterations of the primary structure when compared to order to maintain adequate metabolic fluxes. Thermal compensation in cold-adapted enzymes is reached mesophilic or thermophilic homologues. However, all known structural factors and weak interactions inthrough improved turnover number and catalytic effivolved in protein stability are either reduced in number ciency. This optimization of the catalytic parameters can originate from a highly flexible structure which or modified in order to increase their flexibility.Key words. Psychrophiles; extremophiles; cold adaptation; microbial proteins; protein stability; weak interactions; Antarctic.Psychrophiles live at the lowest temperatures which allow the development of living organisms. These extremophilic organisms, either prokaryotic or eukaryotic, represent a major class of the living world if we consider the vast extent of permanently cold environments on Earth, such as polar and alpine regions or deep-sea waters. The successful colonization of such severe ecological niches by psychrophiles, their diversity and abundance are now well recognized. The lower temperature limit of life is commonly defined as the freezing point of cellular water. Although apparently simple by definition, this limit can drop significantly below 0°C, the freezing point of pure water. For instance, the freezing point of a typical marine teleost ranges between −0.5 and −0.9°C. Sodium chloride is responsible for about 85% of the freezing point depression, and the remaining 15% is due to other small solutes. Synthesis of antifreeze glycoproteins and peptides can further depress the freezing point of body fluids or cellular water. These proteins lower the freezing point by a noncolligative mechanism without altering the melting point significantly, and are therefore also referred to as thermal hysteresis proteins [1,2]. They were first discovered in the blood sera of Antarctic fish living perennially at about −1.9°C, but have been now reported in many organisms including plants, insects, fungi and bacteria [3][4][5]. Levels of thermal hysteresis activity generally range from 0.1 to 0.3°C in bacteria, from 0.2 to 0.5°C in plants, from 0.7 to 1.5°C in fish and from 3 to 6°C in insects. Besides the synthesis of cryoprotectants which lead to freeze avoidance, several organisms have developed mechanisms of freeze tolerance, involving drastic metabolic modifica-* Corresponding author.

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Section: Reviews the Active Site Of Psychrophilic Enzymesmentioning

confidence: 99%

Section: Flexibility-activity Relationshipmentioning

confidence: 99%

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

Section: Structural Factors Affecting the Stability Of Psychrophilic mentioning

confidence: 99%

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Psychrophilic enzymes: molecular basis of cold adaptation

Feller

Gerday

1997

CMLS, Cell. mol. life sci.

371

233

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High resolution structure and sequence ofT. aurantiacus Xylanase I: Implications for the evolution of thermostability in family 10 xylanases and enzymes with ??-barrel architecture

et al. 1999

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Xylanase I is a thermostable xylanase from the fungus Thermoascus aurantiacus, which belongs to family 10 in the current classification of glycosyl hydrolases. We have determined the three-dimensional X-ray structure of this enzyme to near atomic resolution (1.14 A) by molecular replacement, and thereby corrected the chemically determined sequence previously published. Among the five members of family 10 enzymes for which the structure has been determined, Xylanase I from T. aurantiacus and Xylanase Z from C. thermocellum are from thermophilic organisms. A comparison with the three other available structures of the family 10 xylanases from mesophilic organisms suggests that thermostability is effected mainly by improvement of the hydrophobic packing, favorable interactions of charged side chains with the helix dipoles and introduction of prolines at the N-terminus of helices. In contrast to other classes of proteins, there is very little evidence for a contribution of salt bridges to thermostability in the family 10 xylanases from thermophiles. Further analysis of the structures of other proteins from thermophiles with eight-fold (beta)alpha-barrel architecture suggests that favorable interactions of charged side chains with the helix dipoles may be a common way in which thermophilic proteins with this fold are stabilized. As this is the most common type of protein architecture, this finding may provide a useful guide for site-directed mutagenesis aimed to improve the thermostability of (beta)alpha-barrel proteins. Proteins 1999;36:295-306.

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Electrostatics of mesophilic and psychrophilic trypsin isoenzymes: Qualitative evaluation of electrostatic differences at the substrate binding site

et al. 2000

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A qualitative evaluation of electrostatic features of the substrate binding region of seven isoenzymes of trypsin has been performed by using the continuum electrostatic model for the solution of the Poisson-Boltzmann equation. The sources of the electrostatic differences among the trypsins have been sought by comparative calculations on selective charges: all charges, conserved charges, partial charges, unique cold trypsin charges, and a number of charge mutations. As expected, most of the negative potential at the S(1) region of all trypsins is generated from Asp(189), but the potential varies significantly among the seven trypsin isoenzymes. The three cold active enzymes included in this study possess a notably lower potential at and around the S(1)-pocket compared with the warm active counterparts; this finding may be the main contribution to the increased binding affinity. The source of the differences are nonconserved charged residues outside the specificity pocket, producing electric fields at the S(1)-pocket that are different in both sign and magnitude. The surface charges of the mesophilic trypsins generally induce the S(1) pocket positively, whereas surface charges of the cold trypsins produce a negative electric field of this region. Calculations on mutants, where charged amino acids were substituted between the trypsins, showed that mutations in Loop2 (residues 221B and 224) and residue 175, in particular, were responsible for the low potential of the cold enzymes.

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Cold adaption of enzymes: Structural comparison between salmon and bovine trypsins

Cited by 143 publications

References 50 publications

Psychrophilic enzymes: molecular basis of cold adaptation

Psychrophilic enzymes: molecular basis of cold adaptation

High resolution structure and sequence ofT. aurantiacus Xylanase I: Implications for the evolution of thermostability in family 10 xylanases and enzymes with ??-barrel architecture

Electrostatics of mesophilic and psychrophilic trypsin isoenzymes: Qualitative evaluation of electrostatic differences at the substrate binding site

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