Abstract
The effects of temperature on the initial velocity kinetics of allosteric ATP sulfurylase from Penicillium chrysogenum were measured. The experiments were prompted by the structural similarity between the C-terminal regulatory domain of fungal ATP sulfurylase and fungal APS kinase, a homodimer that undergoes a temperature-dependent, reversible dissociation of subunits over a narrow temperature range. Wild-type ATP sulfurylase yielded hyperbolic velocity curves between 18 and 30°C. Increasing the assay temperature above 30°C at a constant pH of 8.0 increased the cooperativity of the velocity curves. Hill coefficients (nH) up to 1.8 were observed at 42°C. The bireactant kinetics at 42°C were the same as those observed at 30°C in the presence of PAPS, the allosteric inhibitor. In contrast, yeast ATP sulfurylase yielded hyperbolic plots at 42°C. The P. chrysogenum mutant enzyme, C509S, which is intrinsically cooperative (nH = 1.8) at 30°C, became more cooperative as the temperature was increased yielding nH values up to 2.9 at 42°C. As the temperature was decreased, the cooperativity of C509S decreased; nH was 1.0 at 18°C. The cumulative results indicate that increasing the temperature increases the allosteric constant, L, i.e., promotes a shift in the base-level distribution of enzyme molecules from the high MgATP affinity R state toward the low MgATP affinity T state. As a result, the enzyme displays a true "temperature optimum" at subsaturating MgATP. The reversible temperature-dependent transitions of fungal ATP sulfurylase and APS kinase may play a role in energy conservation at high temperatures where the organism can survive but not grow optimally.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 51-60 |
| Number of pages | 10 |
| Journal | Archives of Biochemistry and Biophysics |
| Volume | 393 |
| Issue number | 1 |
| DOIs | |
| State | Published - Sep 1 2001 |
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Keywords
- Allosteric behavior
- Allosteric kinetics
- ATP sulfurylase
- Cooperativity
- Kinetics
- P. chrysogenum
- Sulfurylase
- Temperature effect
- Temperature optimum
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology
Cite this
Temperature effects on the allosteric transition of ATP sulfurylase from Penicillium chrysogenum. / Medina, D. C.; Hanna, E.; MacRae, I. J.; Fisher, Andrew J; Segel, I. H.
In: Archives of Biochemistry and Biophysics, Vol. 393, No. 1, 01.09.2001, p. 51-60.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Temperature effects on the allosteric transition of ATP sulfurylase from Penicillium chrysogenum
AU - Medina, D. C.
AU - Hanna, E.
AU - MacRae, I. J.
AU - Fisher, Andrew J
AU - Segel, I. H.
PY - 2001/9/1
Y1 - 2001/9/1
N2 - The effects of temperature on the initial velocity kinetics of allosteric ATP sulfurylase from Penicillium chrysogenum were measured. The experiments were prompted by the structural similarity between the C-terminal regulatory domain of fungal ATP sulfurylase and fungal APS kinase, a homodimer that undergoes a temperature-dependent, reversible dissociation of subunits over a narrow temperature range. Wild-type ATP sulfurylase yielded hyperbolic velocity curves between 18 and 30°C. Increasing the assay temperature above 30°C at a constant pH of 8.0 increased the cooperativity of the velocity curves. Hill coefficients (nH) up to 1.8 were observed at 42°C. The bireactant kinetics at 42°C were the same as those observed at 30°C in the presence of PAPS, the allosteric inhibitor. In contrast, yeast ATP sulfurylase yielded hyperbolic plots at 42°C. The P. chrysogenum mutant enzyme, C509S, which is intrinsically cooperative (nH = 1.8) at 30°C, became more cooperative as the temperature was increased yielding nH values up to 2.9 at 42°C. As the temperature was decreased, the cooperativity of C509S decreased; nH was 1.0 at 18°C. The cumulative results indicate that increasing the temperature increases the allosteric constant, L, i.e., promotes a shift in the base-level distribution of enzyme molecules from the high MgATP affinity R state toward the low MgATP affinity T state. As a result, the enzyme displays a true "temperature optimum" at subsaturating MgATP. The reversible temperature-dependent transitions of fungal ATP sulfurylase and APS kinase may play a role in energy conservation at high temperatures where the organism can survive but not grow optimally.
AB - The effects of temperature on the initial velocity kinetics of allosteric ATP sulfurylase from Penicillium chrysogenum were measured. The experiments were prompted by the structural similarity between the C-terminal regulatory domain of fungal ATP sulfurylase and fungal APS kinase, a homodimer that undergoes a temperature-dependent, reversible dissociation of subunits over a narrow temperature range. Wild-type ATP sulfurylase yielded hyperbolic velocity curves between 18 and 30°C. Increasing the assay temperature above 30°C at a constant pH of 8.0 increased the cooperativity of the velocity curves. Hill coefficients (nH) up to 1.8 were observed at 42°C. The bireactant kinetics at 42°C were the same as those observed at 30°C in the presence of PAPS, the allosteric inhibitor. In contrast, yeast ATP sulfurylase yielded hyperbolic plots at 42°C. The P. chrysogenum mutant enzyme, C509S, which is intrinsically cooperative (nH = 1.8) at 30°C, became more cooperative as the temperature was increased yielding nH values up to 2.9 at 42°C. As the temperature was decreased, the cooperativity of C509S decreased; nH was 1.0 at 18°C. The cumulative results indicate that increasing the temperature increases the allosteric constant, L, i.e., promotes a shift in the base-level distribution of enzyme molecules from the high MgATP affinity R state toward the low MgATP affinity T state. As a result, the enzyme displays a true "temperature optimum" at subsaturating MgATP. The reversible temperature-dependent transitions of fungal ATP sulfurylase and APS kinase may play a role in energy conservation at high temperatures where the organism can survive but not grow optimally.
KW - Allosteric behavior
KW - Allosteric kinetics
KW - ATP sulfurylase
KW - Cooperativity
KW - Kinetics
KW - P. chrysogenum
KW - Sulfurylase
KW - Temperature effect
KW - Temperature optimum
UR - http://www.scopus.com/inward/record.url?scp=0035450904&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035450904&partnerID=8YFLogxK
U2 - 10.1006/abbi.2001.2490
DO - 10.1006/abbi.2001.2490
M3 - Article
C2 - 11516160
AN - SCOPUS:0035450904
VL - 393
SP - 51
EP - 60
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 1
ER -