Distinct roles of an ionic interaction holding an alpha-helix with catalytic Asp and a beta-strand with catalytic His in a hyperthermophilic esterase EstE1 and a mesophilic esterase rPPE

Dachuri, VinayKumar; Truongvan, Ngoc; DangThu, Quynh; Jang, Sei‐Heon; Lee, ChangWoo

doi:10.1007/s00792-019-01115-6

Cited by 3 publications

(3 citation statements)

References 31 publications

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“…The disruption of the salt bridge in the structurally rigid EstE1 increased the conformational flexibility of the protein significantly but had a lesser effect on the thermal stability [40]. In contrast, the disruption of the salt bridge in the relatively flexible rPPE had a lesser effect on the conformational flexibility but resulted in reduced thermal stability [40]. These results are consistent with those on rPPE in that the alanine-substituted PML mutants showed a larger change in thermal stability than conformational flexibility in an aqueous buffer because the structure of PML is intrinsically flexible.…”

Section: Discussionmentioning

confidence: 99%

“…The residues surrounding the catalytic site help provide the correct spatial relationship. The salt bridge that stabilizes the α-helix with catalytic aspartate and the β-strand with catalytic histidine (the interaction between R237 and D248 in PML) is highly conserved in many esterases, including hyperthermophilic esterase EstE1 (optimal temperature 70 • C) and mesophilic esterase rPPE (optimal temperature 50 • C) [40]. The disruption of the salt bridge in the structurally rigid EstE1 increased the conformational flexibility of the protein significantly but had a lesser effect on the thermal stability [40].…”

Section: Discussionmentioning

confidence: 99%

“…The salt bridge that stabilizes the α-helix with catalytic aspartate and the β-strand with catalytic histidine (the interaction between R237 and D248 in PML) is highly conserved in many esterases, including hyperthermophilic esterase EstE1 (optimal temperature 70 • C) and mesophilic esterase rPPE (optimal temperature 50 • C) [40]. The disruption of the salt bridge in the structurally rigid EstE1 increased the conformational flexibility of the protein significantly but had a lesser effect on the thermal stability [40]. In contrast, the disruption of the salt bridge in the relatively flexible rPPE had a lesser effect on the conformational flexibility but resulted in reduced thermal stability [40].…”

Section: Discussionmentioning

confidence: 99%

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Different Effects of Salt Bridges near the Active Site of Cold-Adapted Proteus mirabilis Lipase on Thermal and Organic Solvent Stabilities

2022

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Organic solvent-tolerant (OST) enzymes have been discovered in psychrophiles. Cold-adapted OST enzymes exhibit increased conformational flexibility in polar organic solvents resulting from their intrinsically flexible structures. Proteus mirabilis lipase (PML), a cold-adapted OST lipase, was used to assess the contribution of salt bridges near the active site involving two arginine residues (R237 and R241) on the helix η1 and an aspartate residue (D248) on the connecting loop to the thermal and organic solvent stabilities of PML. Alanine substitutions for the ion pairs (R237A, R241A, D248A, and R237A/D248A) increased the conformational flexibility of PML mutants compared to that of the wild-type PML in an aqueous buffer. The PML mutants became more susceptible to denaturation after increasing the dimethyl sulfoxide or methanol concentration than after a temperature increase. Methanol was more detrimental to the structural stability of PML compared to dimethyl sulfoxide. These results suggest that direct interactions of dimethyl sulfoxide and methanol with the residues near the active site can have a destructive effect on the structure of PML compared with the global effect of heat on the protein structure. This study provides insight into the conformational changes within an OST enzyme with different effects on its thermal and organic solvent stabilities.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%