Fluorescence Study of the Three Tryptophan Residues of the Pore-Forming Domain of Colicin A Using Multifrequency Phase Fluorometry

Rita Vos, Yves Engelborghs, Jacques Izard, Daniel Baty

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

We have identified the steady-state and time-resolved fluorescence of the three tryptophan residues (Trp-86, Trp-130, and Trp-140) of the pore-forming domain of colicin A using site-directed mutagenesis in order to construct two- and one-tryptophan-containing mutant proteins. Fluorescence lifetimes were measured via multifrequency phase fluorometry. The fluorescence of the pore-forming domain of colicin A is dominated by Trp-140 which contributes almost 53% to the fluorescence intensity. Mutation of Trp-140 results in a decrease in fluorescence quantum yield and average lifetime. Colicin A wild-type and all mutant proteins display multiple lifetimes which belong to three different lifetime classes: 0.38-0.57 ns for τ1, 1.6-1.87 ns for τ2, and 3.6-4.41 ns for τ3 at pH 5. At pH 7, the three classes are 0.64-0.89 ns for τ2, 2.01-2.19 ns for τ2, and 4.23-4.94 ns for τ3. This pH effect influences all the lifetimes and must be attributed to a general conformational change. In wild-type colicin A, rg originates mainly from Trp-140 while Trp-86 and Trp-130 both provide a major contribution to τ2. The pH dependence of the fluorescence intensity gives rise to a pKa of 5.2. The different lifetime components of two of the three single-tryptophan-containing mutants show different quenching properties toward acrylamide, indicating that each lifetime is coupled to a different microenvironment. The linear combination of the lifetimes of the single tryptophans into pairs simulates very well the behavior of the two-tryptophancontaining mutants except for one, the mutant containing Trp-86 and Trp-130. The lifetimes of the wildtype protein can only be obtained by the linear combination of the lifetimes from the mutant containing the tryptophan pair Trp-86/Trp-130 and the mutant containing Trp-140. Mutual energy transfer between Trp-86 and Trp-130 is assumed to be the explanation of this deviation since the mutant proteins display no structural or dynamic aberrances. The calculated energy transfer efficiency amounts to 65% for energy transfer from Trp-86 to Trp-130 and 21% for the reverse transfer and is in agreement with our measurements.

Original languageEnglish (US)
Pages (from-to)1734-1743
Number of pages10
JournalBiochemistry
Volume34
Issue number5
DOIs
StatePublished - Feb 1995

Fingerprint

Colicins
Fluorometry
Tryptophan
Fluorescence
Energy Transfer
Mutant Proteins
Energy transfer
pH effects
Mutagenesis
Acrylamide
Quantum yield
Site-Directed Mutagenesis
Quenching
Mutation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Fluorescence Study of the Three Tryptophan Residues of the Pore-Forming Domain of Colicin A Using Multifrequency Phase Fluorometry. / Vos, Rita; Engelborghs, Yves; Izard, Jacques; Baty, Daniel.

In: Biochemistry, Vol. 34, No. 5, 02.1995, p. 1734-1743.

Research output: Contribution to journalArticle

@article{1fdc945acd314af8b8471b16b6a06e6c,
title = "Fluorescence Study of the Three Tryptophan Residues of the Pore-Forming Domain of Colicin A Using Multifrequency Phase Fluorometry",
abstract = "We have identified the steady-state and time-resolved fluorescence of the three tryptophan residues (Trp-86, Trp-130, and Trp-140) of the pore-forming domain of colicin A using site-directed mutagenesis in order to construct two- and one-tryptophan-containing mutant proteins. Fluorescence lifetimes were measured via multifrequency phase fluorometry. The fluorescence of the pore-forming domain of colicin A is dominated by Trp-140 which contributes almost 53{\%} to the fluorescence intensity. Mutation of Trp-140 results in a decrease in fluorescence quantum yield and average lifetime. Colicin A wild-type and all mutant proteins display multiple lifetimes which belong to three different lifetime classes: 0.38-0.57 ns for τ1, 1.6-1.87 ns for τ2, and 3.6-4.41 ns for τ3 at pH 5. At pH 7, the three classes are 0.64-0.89 ns for τ2, 2.01-2.19 ns for τ2, and 4.23-4.94 ns for τ3. This pH effect influences all the lifetimes and must be attributed to a general conformational change. In wild-type colicin A, rg originates mainly from Trp-140 while Trp-86 and Trp-130 both provide a major contribution to τ2. The pH dependence of the fluorescence intensity gives rise to a pKa of 5.2. The different lifetime components of two of the three single-tryptophan-containing mutants show different quenching properties toward acrylamide, indicating that each lifetime is coupled to a different microenvironment. The linear combination of the lifetimes of the single tryptophans into pairs simulates very well the behavior of the two-tryptophancontaining mutants except for one, the mutant containing Trp-86 and Trp-130. The lifetimes of the wildtype protein can only be obtained by the linear combination of the lifetimes from the mutant containing the tryptophan pair Trp-86/Trp-130 and the mutant containing Trp-140. Mutual energy transfer between Trp-86 and Trp-130 is assumed to be the explanation of this deviation since the mutant proteins display no structural or dynamic aberrances. The calculated energy transfer efficiency amounts to 65{\%} for energy transfer from Trp-86 to Trp-130 and 21{\%} for the reverse transfer and is in agreement with our measurements.",
author = "Rita Vos and Yves Engelborghs and Jacques Izard and Daniel Baty",
year = "1995",
month = "2",
doi = "10.1021/bi00005a030",
language = "English (US)",
volume = "34",
pages = "1734--1743",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "5",

}

TY - JOUR

T1 - Fluorescence Study of the Three Tryptophan Residues of the Pore-Forming Domain of Colicin A Using Multifrequency Phase Fluorometry

AU - Vos, Rita

AU - Engelborghs, Yves

AU - Izard, Jacques

AU - Baty, Daniel

PY - 1995/2

Y1 - 1995/2

N2 - We have identified the steady-state and time-resolved fluorescence of the three tryptophan residues (Trp-86, Trp-130, and Trp-140) of the pore-forming domain of colicin A using site-directed mutagenesis in order to construct two- and one-tryptophan-containing mutant proteins. Fluorescence lifetimes were measured via multifrequency phase fluorometry. The fluorescence of the pore-forming domain of colicin A is dominated by Trp-140 which contributes almost 53% to the fluorescence intensity. Mutation of Trp-140 results in a decrease in fluorescence quantum yield and average lifetime. Colicin A wild-type and all mutant proteins display multiple lifetimes which belong to three different lifetime classes: 0.38-0.57 ns for τ1, 1.6-1.87 ns for τ2, and 3.6-4.41 ns for τ3 at pH 5. At pH 7, the three classes are 0.64-0.89 ns for τ2, 2.01-2.19 ns for τ2, and 4.23-4.94 ns for τ3. This pH effect influences all the lifetimes and must be attributed to a general conformational change. In wild-type colicin A, rg originates mainly from Trp-140 while Trp-86 and Trp-130 both provide a major contribution to τ2. The pH dependence of the fluorescence intensity gives rise to a pKa of 5.2. The different lifetime components of two of the three single-tryptophan-containing mutants show different quenching properties toward acrylamide, indicating that each lifetime is coupled to a different microenvironment. The linear combination of the lifetimes of the single tryptophans into pairs simulates very well the behavior of the two-tryptophancontaining mutants except for one, the mutant containing Trp-86 and Trp-130. The lifetimes of the wildtype protein can only be obtained by the linear combination of the lifetimes from the mutant containing the tryptophan pair Trp-86/Trp-130 and the mutant containing Trp-140. Mutual energy transfer between Trp-86 and Trp-130 is assumed to be the explanation of this deviation since the mutant proteins display no structural or dynamic aberrances. The calculated energy transfer efficiency amounts to 65% for energy transfer from Trp-86 to Trp-130 and 21% for the reverse transfer and is in agreement with our measurements.

AB - We have identified the steady-state and time-resolved fluorescence of the three tryptophan residues (Trp-86, Trp-130, and Trp-140) of the pore-forming domain of colicin A using site-directed mutagenesis in order to construct two- and one-tryptophan-containing mutant proteins. Fluorescence lifetimes were measured via multifrequency phase fluorometry. The fluorescence of the pore-forming domain of colicin A is dominated by Trp-140 which contributes almost 53% to the fluorescence intensity. Mutation of Trp-140 results in a decrease in fluorescence quantum yield and average lifetime. Colicin A wild-type and all mutant proteins display multiple lifetimes which belong to three different lifetime classes: 0.38-0.57 ns for τ1, 1.6-1.87 ns for τ2, and 3.6-4.41 ns for τ3 at pH 5. At pH 7, the three classes are 0.64-0.89 ns for τ2, 2.01-2.19 ns for τ2, and 4.23-4.94 ns for τ3. This pH effect influences all the lifetimes and must be attributed to a general conformational change. In wild-type colicin A, rg originates mainly from Trp-140 while Trp-86 and Trp-130 both provide a major contribution to τ2. The pH dependence of the fluorescence intensity gives rise to a pKa of 5.2. The different lifetime components of two of the three single-tryptophan-containing mutants show different quenching properties toward acrylamide, indicating that each lifetime is coupled to a different microenvironment. The linear combination of the lifetimes of the single tryptophans into pairs simulates very well the behavior of the two-tryptophancontaining mutants except for one, the mutant containing Trp-86 and Trp-130. The lifetimes of the wildtype protein can only be obtained by the linear combination of the lifetimes from the mutant containing the tryptophan pair Trp-86/Trp-130 and the mutant containing Trp-140. Mutual energy transfer between Trp-86 and Trp-130 is assumed to be the explanation of this deviation since the mutant proteins display no structural or dynamic aberrances. The calculated energy transfer efficiency amounts to 65% for energy transfer from Trp-86 to Trp-130 and 21% for the reverse transfer and is in agreement with our measurements.

UR - http://www.scopus.com/inward/record.url?scp=0028961326&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028961326&partnerID=8YFLogxK

U2 - 10.1021/bi00005a030

DO - 10.1021/bi00005a030

M3 - Article

C2 - 7849033

AN - SCOPUS:0028961326

VL - 34

SP - 1734

EP - 1743

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 5

ER -