Abstract
The static and dynamical behavior of a fluorescently labeled mutant of the Escherichia coli periplasmic phosphate binding protein (PBP) was investigated through steady-state and time-resolved fluorescence spectroscopy. As a means of developing a biorecognition element for inorganic phosphate (Pi), alanine-197 of PBP was replaced with a cysteine. This site was then labeled with an environmentally sensitive fluorophore. The fluorescence emission of the mutant PBP labeled with acrylodan (MPBP-AC) proved to be sensitive to micromolar concentrations of P(i), as indicated by a 50% increase in the steady-state emission intensity. Steady-state results indicated that the labeling protocol was specific for cys-197 only and did not label the wild-type PBP; thus, a site-selective labeling protocol was developed. Time-resolved measurements were used to determine the influence of the dynamics of MPBP-AC on the process of signal transduction. Time-resolved anisotropy measurements revealed that rotational dynamics were best described by a model with two independent motions: the global motion of the protein and the local motion of the acrylodan probe. The rates of both global and local rotational reorientation of MPBP-AC were faster when the protein was P(i)- bound rather than P(i)-free. This was a result of structural changes involving or surrounding both the P(i)-binding site (global changes) and the residues in near proximity to the fluorescent reporter group (local changes). Recovery of the semiangle (θ) indicated that local structural changes in MPBP-AC took place when P(i) was bound to the protein. Acrylodan gained mobility when MPBP-AC hound P(i), as indicated by the fact that θ increased by approximately 5°. In addition, dynamic quenching measurements confirmed that structural changes occurred locally near the cys-197. Acrylodan became more accessible to iodide when MPBP-AC bound P(i), as demonstrated by the 35% increase in the value of the bimolecular quenching constant.
| Original language | English |
|---|---|
| Pages (from-to) | 589-595 |
| Number of pages | 7 |
| Journal | Analytical Chemistry |
| Volume | 71 |
| Issue number | 3 |
| DOIs | |
| State | Published - Feb 1 1999 |
| Externally published | Yes |
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- Analytical Chemistry
Cite this
A dynamical investigation of acrylodan-labeled mutant phosphate binding protein. / Lundgren, Jeffrey S.; Salins, Lyndon L E; Kaneva, Irina; Daunert, Sylvia.
In: Analytical Chemistry, Vol. 71, No. 3, 01.02.1999, p. 589-595.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A dynamical investigation of acrylodan-labeled mutant phosphate binding protein
AU - Lundgren, Jeffrey S.
AU - Salins, Lyndon L E
AU - Kaneva, Irina
AU - Daunert, Sylvia
PY - 1999/2/1
Y1 - 1999/2/1
N2 - The static and dynamical behavior of a fluorescently labeled mutant of the Escherichia coli periplasmic phosphate binding protein (PBP) was investigated through steady-state and time-resolved fluorescence spectroscopy. As a means of developing a biorecognition element for inorganic phosphate (Pi), alanine-197 of PBP was replaced with a cysteine. This site was then labeled with an environmentally sensitive fluorophore. The fluorescence emission of the mutant PBP labeled with acrylodan (MPBP-AC) proved to be sensitive to micromolar concentrations of P(i), as indicated by a 50% increase in the steady-state emission intensity. Steady-state results indicated that the labeling protocol was specific for cys-197 only and did not label the wild-type PBP; thus, a site-selective labeling protocol was developed. Time-resolved measurements were used to determine the influence of the dynamics of MPBP-AC on the process of signal transduction. Time-resolved anisotropy measurements revealed that rotational dynamics were best described by a model with two independent motions: the global motion of the protein and the local motion of the acrylodan probe. The rates of both global and local rotational reorientation of MPBP-AC were faster when the protein was P(i)- bound rather than P(i)-free. This was a result of structural changes involving or surrounding both the P(i)-binding site (global changes) and the residues in near proximity to the fluorescent reporter group (local changes). Recovery of the semiangle (θ) indicated that local structural changes in MPBP-AC took place when P(i) was bound to the protein. Acrylodan gained mobility when MPBP-AC hound P(i), as indicated by the fact that θ increased by approximately 5°. In addition, dynamic quenching measurements confirmed that structural changes occurred locally near the cys-197. Acrylodan became more accessible to iodide when MPBP-AC bound P(i), as demonstrated by the 35% increase in the value of the bimolecular quenching constant.
AB - The static and dynamical behavior of a fluorescently labeled mutant of the Escherichia coli periplasmic phosphate binding protein (PBP) was investigated through steady-state and time-resolved fluorescence spectroscopy. As a means of developing a biorecognition element for inorganic phosphate (Pi), alanine-197 of PBP was replaced with a cysteine. This site was then labeled with an environmentally sensitive fluorophore. The fluorescence emission of the mutant PBP labeled with acrylodan (MPBP-AC) proved to be sensitive to micromolar concentrations of P(i), as indicated by a 50% increase in the steady-state emission intensity. Steady-state results indicated that the labeling protocol was specific for cys-197 only and did not label the wild-type PBP; thus, a site-selective labeling protocol was developed. Time-resolved measurements were used to determine the influence of the dynamics of MPBP-AC on the process of signal transduction. Time-resolved anisotropy measurements revealed that rotational dynamics were best described by a model with two independent motions: the global motion of the protein and the local motion of the acrylodan probe. The rates of both global and local rotational reorientation of MPBP-AC were faster when the protein was P(i)- bound rather than P(i)-free. This was a result of structural changes involving or surrounding both the P(i)-binding site (global changes) and the residues in near proximity to the fluorescent reporter group (local changes). Recovery of the semiangle (θ) indicated that local structural changes in MPBP-AC took place when P(i) was bound to the protein. Acrylodan gained mobility when MPBP-AC hound P(i), as indicated by the fact that θ increased by approximately 5°. In addition, dynamic quenching measurements confirmed that structural changes occurred locally near the cys-197. Acrylodan became more accessible to iodide when MPBP-AC bound P(i), as demonstrated by the 35% increase in the value of the bimolecular quenching constant.
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U2 - 10.1021/ac980800g
DO - 10.1021/ac980800g
M3 - Article
C2 - 9989379
AN - SCOPUS:0033084057
VL - 71
SP - 589
EP - 595
JO - Analytical Chemistry
JF - Analytical Chemistry
SN - 0003-2700
IS - 3
ER -