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Half-Barrels Derived from a (β/α)8 Barrel β-Glycosidase Undergo an Activation Process.

Beton D, Marana SR - PLoS ONE (2015)

Bottom Line: The rate constants of the activation process were calculated to be 0.029 and 0.032 h-1 for Sfβgly-N and Sfβgly-C, respectively.Importantly, this activation was also coincident with an increase in the sizes of Sfβgly-N and Sfβgly-C particles.These novel observations suggest that the change in catalytic activity associated with the transition from a half to whole (β/α)8 barrel might also have driven such an evolutionary process.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.

ABSTRACT
The evolution of (β/α)8 barrel proteins is currently thought to have involved the fusion of two (β/α)4 half-barrels, thereby conferring stability on the protein structure. After the formation of a whole (β/α)8 barrel, this structure could evolve and diverge to form fully active enzymes. Interestingly, we show here that isolated (β/α)4 half-barrels derived from the N- and C-terminal domains of the β-glucosidase Sfβgly (Sfβgly-N: residues 1 to 265; Sfβgly-C: residues 266 to 509) undergo an activation process, which renders them catalytically active. The rate constants of the activation process were calculated to be 0.029 and 0.032 h-1 for Sfβgly-N and Sfβgly-C, respectively. Moreover, the Sfβgly-N and Sfβgly-C activation processes were simultaneous with modifications in their initial structure, which reduced the exposure of their tryptophan residues. Importantly, this activation was also coincident with an increase in the sizes of Sfβgly-N and Sfβgly-C particles. These novel observations suggest that the change in catalytic activity associated with the transition from a half to whole (β/α)8 barrel might also have driven such an evolutionary process.

No MeSH data available.


Related in: MedlinePlus

Circular dichroism spectra for Sfβgly-N and Sfβgly-C.Purified samples of 0.22 mg/mL Sfβgly-N (A) and 0.25 mg/mL Sfβgly-C (B) prepared in 10 mM potassium phosphate buffer, pH 6.9, were used for spectrum determination at 25°C (n = 8 reads).
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pone.0139673.g003: Circular dichroism spectra for Sfβgly-N and Sfβgly-C.Purified samples of 0.22 mg/mL Sfβgly-N (A) and 0.25 mg/mL Sfβgly-C (B) prepared in 10 mM potassium phosphate buffer, pH 6.9, were used for spectrum determination at 25°C (n = 8 reads).

Mentions: To understand the putative modifications that Sfβgly-N and Sfβgly-C are subjected to during the activation process, we physically characterized these half-barrels. Initially, circular dichroism spectra indicated that both half-barrels had a secondary structure (Fig 3). Sfβgly-N is mainly composed of α-helices (64%) and unstructured regions (33%), whereas β-strands are a minor component (3%). Conversely, Sfβgly-C is mainly composed of unstructured regions (49%) and β-strands (47%), and α-helices are a minor component (4%).


Half-Barrels Derived from a (β/α)8 Barrel β-Glycosidase Undergo an Activation Process.

Beton D, Marana SR - PLoS ONE (2015)

Circular dichroism spectra for Sfβgly-N and Sfβgly-C.Purified samples of 0.22 mg/mL Sfβgly-N (A) and 0.25 mg/mL Sfβgly-C (B) prepared in 10 mM potassium phosphate buffer, pH 6.9, were used for spectrum determination at 25°C (n = 8 reads).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591997&req=5

pone.0139673.g003: Circular dichroism spectra for Sfβgly-N and Sfβgly-C.Purified samples of 0.22 mg/mL Sfβgly-N (A) and 0.25 mg/mL Sfβgly-C (B) prepared in 10 mM potassium phosphate buffer, pH 6.9, were used for spectrum determination at 25°C (n = 8 reads).
Mentions: To understand the putative modifications that Sfβgly-N and Sfβgly-C are subjected to during the activation process, we physically characterized these half-barrels. Initially, circular dichroism spectra indicated that both half-barrels had a secondary structure (Fig 3). Sfβgly-N is mainly composed of α-helices (64%) and unstructured regions (33%), whereas β-strands are a minor component (3%). Conversely, Sfβgly-C is mainly composed of unstructured regions (49%) and β-strands (47%), and α-helices are a minor component (4%).

Bottom Line: The rate constants of the activation process were calculated to be 0.029 and 0.032 h-1 for Sfβgly-N and Sfβgly-C, respectively.Importantly, this activation was also coincident with an increase in the sizes of Sfβgly-N and Sfβgly-C particles.These novel observations suggest that the change in catalytic activity associated with the transition from a half to whole (β/α)8 barrel might also have driven such an evolutionary process.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.

ABSTRACT
The evolution of (β/α)8 barrel proteins is currently thought to have involved the fusion of two (β/α)4 half-barrels, thereby conferring stability on the protein structure. After the formation of a whole (β/α)8 barrel, this structure could evolve and diverge to form fully active enzymes. Interestingly, we show here that isolated (β/α)4 half-barrels derived from the N- and C-terminal domains of the β-glucosidase Sfβgly (Sfβgly-N: residues 1 to 265; Sfβgly-C: residues 266 to 509) undergo an activation process, which renders them catalytically active. The rate constants of the activation process were calculated to be 0.029 and 0.032 h-1 for Sfβgly-N and Sfβgly-C, respectively. Moreover, the Sfβgly-N and Sfβgly-C activation processes were simultaneous with modifications in their initial structure, which reduced the exposure of their tryptophan residues. Importantly, this activation was also coincident with an increase in the sizes of Sfβgly-N and Sfβgly-C particles. These novel observations suggest that the change in catalytic activity associated with the transition from a half to whole (β/α)8 barrel might also have driven such an evolutionary process.

No MeSH data available.


Related in: MedlinePlus