DB code: S00179

RLCP classification	1.14.36110.975 : Hydrolysis
CATH domain	3.10.129.10 : Thiol Ester Dehydrase; Chain A	Catalytic domain
E.C.	3.1.2.23
CSA
M-CSA
MACiE

CATH domain	Related DB codes (homologues)
3.10.129.10 : Thiol Ester Dehydrase; Chain A	S00180

Uniprot Enzyme Name
UniprotKB	Protein name	Synonyms	Pfam
P56653	4-hydroxybenzoyl-CoA thioesterase	EC 3.1.2.23	PF03061 (4HBT) [Graphical View]

KEGG enzyme name
4-hydroxybenzoyl-CoA thioesterase

UniprotKB: Accession Number	Entry name	Activity	Subunit	Subcellular location	Cofactor
P56653	4HBT_PSEUC	4-hydroxybenzoyl-CoA + H(2)O = 4- hydroxybenzoate + CoA.	Homotetramer.

KEGG Pathways
Map code	Pathways	E.C.
MAP00623	2,4-Dichlorobenzoate degradation

Compound table
	Substrates		Products		Intermediates
KEGG-id	C02949	C00001	C00010	C00156
E.C.
Compound	4-Hydroxybenzoyl-CoA	H2O	CoA	4-Hydroxybenzoate
Type	amine group,aromatic ring (only carbon atom),carbohydrate,nucleotide ,peptide/protein,sulfide group	H2O	amine group,carbohydrate,nucleotide ,peptide/protein,sulfhydryl group	aromatic ring (only carbon atom),carboxyl group
ChEBI	15500 15500	15377 15377	15346 15346	30763 30763
PubChem	168718 439862 168718 439862	22247451 962 22247451 962	6816 87642 6816 87642	135 3702506 135 3702506

1bvqA	Unbound		Unbound	Unbound
1lo7A	Analogue:4CO		Unbound	Unbound
1lo8A	Analogue:4CA		Unbound	Unbound
1lo9A	Bound:BCA		Unbound	Unbound

Reference for Active-site residues
resource	references	E.C.
literature [2], [3], [4]

Active-site residues
PDB	Catalytic residues	Cofactor-binding residues	Modified residues	Main-chain involved in catalysis	Comment

1bvqA	ASP 17;ASP 32			TYR 24
1lo7A	ASP 17;ASP 32			TYR 24
1lo8A	ASP 17;ASP 32			TYR 24
1lo9A	;ASP 32			TYR 24	mutant D17N

References for Catalytic Mechanism
References	Sections	No. of steps in catalysis
[1]	p.33576-33578
[2]	Fig.7	2
[3]	p.27474-27476

References
[1]
Resource
Comments	X-RAY CRYSTALLOGRAPHY (2.0 ANGSTROMS).
Medline ID	99057924
PubMed ID	9837940
Journal	J Biol Chem
Year	1998
Volume	273
Pages	33572-9
Authors	Benning MM, Wesenberg G, Liu R, Taylor KL, Dunaway-Mariano D, Holden HM
Title	The three-dimensional structure of 4-hydroxybenzoyl-CoA thioesterase from Pseudomonas sp. Strain CBS-3.
Related PDB	1bvq
Related UniProtKB	P56653
[2]
Resource
Comments
Medline ID
PubMed ID	12220180
Journal	Biochemistry
Year	2002
Volume	41
Pages	11152-60
Authors	Zhuang Z, Song F, Zhang W, Taylor K, Archambault A, Dunaway-Mariano D, Dong J, Carey PR
Title	Kinetic, Raman, NMR, and site-directed mutagenesis studies of the Pseudomonas sp. strain CBS3 4-hydroxybenzoyl-CoA thioesterase active site.
Related PDB
Related UniProtKB
[3]
Resource
Comments	X-ray crystallography
Medline ID
PubMed ID	11997398
Journal	J Biol Chem
Year	2002
Volume	277
Pages	27468-76
Authors	Thoden JB, Holden HM, Zhuang Z, Dunaway-Mariano D
Title	X-ray crystallographic analyses of inhibitor and substrate complexes of wild-type and mutant 4-hydroxybenzoyl-CoA thioesterase.
Related PDB	1lo7 1lo8 1lo9
Related UniProtKB
[4]
Resource
Comments
Medline ID
PubMed ID	12907670
Journal	J Biol Chem
Year	2003
Volume	278
Pages	43709-16
Authors	Thoden JB, Zhuang Z, Dunaway-Mariano D, Holden HM
Title	The structure of 4-hydroxybenzoyl-CoA thioesterase from arthrobacter sp. strain SU.
Related PDB	1q4s 1q4t 1q4u
Related UniProtKB

Comments
Originally, this data was for E.C. 3.8.1.6. However, the Swiss-prot data and literature suggest that the function must be for E.C. 3.1.2.23. The active site residues are contributed by the second subunit of the homodimer or homotetramer [1]. Asp17 serves as the putative base catalyst [1]. OD1 atom of Asp17 is located at 6.0 A from the substrate thioester carbon, providing the adequate space between the substrate and Asp17 for the positioning of a water molecule for nucleophilic attack during the catalysis. The backbone amide atom of Ile61 is within hydrogen bonding distance to the thioester oxygen, whose interaction could result in the polarization of the carbonyl C=O bond, thereby activating the carbonyl carbon for nucleophilic attack, and in the stabilization of the developing oxyanion transition state [1]. On the other hand, mainchain amide group of Tyr24 plays this role, according to the literature ([3] & [4]). According to the literature [2] and [3], the catalytic role played by Asp17 seems to be a nucleophile which makes an attack directly on the acyl carbon of the thioester substrate to form an anhydride enzyme intermediate. However, a question still remains. If the catalytic reaction proceeds via the intermediate, then the water nucleophile binds and attacks at the carbonyl carbon. According to the literature [4], although the homodimer structures with ligand of its homologous enzyme have been determined, the active site is not the same as that of this enzyme (see PDB;1q4s, 1q4t, 1q4u). However, comparison with the structure suggests that Asp32 may act as a general base, which activate a water, since Glu73 of the counterpart enzyme seems to play the role (see [4]). Taken together, the catalytic reaction proceeds as follows: (1) Mainchain amide group of Tyr24 polarizes and activates the carbonyl oxygen of thioester for nucleophilic attack. (This suggests dissociative reaction.) (2) Asp17 acts as a nucleophile, which attacks on the thioester carbonyl carbon, leading to formation of a tetrahedral transition-state. The oxyanion of the transition-state is stabilized by the mainchain amide of Tyr24. (3) This collapses, leading to the formation of acyl intermediate and release of CoA. (The leaving sulfur atom of CoA might be protonated by Asp32 from the next subunit.) (4) Asp32 from the next subunit acts as a general base, which activates a water moleucle. (5) The activated water makes a nucleophilic attack on the acyl intermediate, completing the reaction.

Comments

Originally, this data was for E.C. 3.8.1.6. However, the Swiss-prot data and literature suggest that the function must be for E.C. 3.1.2.23.
The active site residues are contributed by the second subunit of the homodimer or homotetramer [1].
Asp17 serves as the putative base catalyst [1]. OD1 atom of Asp17 is located at 6.0 A from the substrate thioester carbon, providing the adequate space between the substrate and Asp17 for the positioning of a water molecule for nucleophilic attack during the catalysis. The backbone amide atom of Ile61 is within hydrogen bonding distance to the thioester oxygen, whose interaction could result in the polarization of the carbonyl C=O bond, thereby activating the carbonyl carbon for nucleophilic attack, and in the stabilization of the developing oxyanion transition state [1]. On the other hand, mainchain amide group of Tyr24 plays this role, according to the literature ([3] & [4]).
According to the literature [2] and [3], the catalytic role played by Asp17 seems to be a nucleophile which makes an attack directly on the acyl carbon of the thioester substrate to form an anhydride enzyme intermediate. However, a question still remains. If the catalytic reaction proceeds via the intermediate, then the water nucleophile binds and attacks at the carbonyl carbon.
According to the literature [4], although the homodimer structures with ligand of its homologous enzyme have been determined, the active site is not the same as that of this enzyme (see PDB;1q4s, 1q4t, 1q4u). However, comparison with the structure suggests that Asp32 may act as a general base, which activate a water, since Glu73 of the counterpart enzyme seems to play the role (see [4]).
Taken together, the catalytic reaction proceeds as follows:
(1) Mainchain amide group of Tyr24 polarizes and activates the carbonyl oxygen of thioester for nucleophilic attack. (This suggests dissociative reaction.)
(2) Asp17 acts as a nucleophile, which attacks on the thioester carbonyl carbon, leading to formation of a tetrahedral transition-state. The oxyanion of the transition-state is stabilized by the mainchain amide of Tyr24.
(3) This collapses, leading to the formation of acyl intermediate and release of CoA. (The leaving sulfur atom of CoA might be protonated by Asp32 from the next subunit.)
(4) Asp32 from the next subunit acts as a general base, which activates a water moleucle.
(5) The activated water makes a nucleophilic attack on the acyl intermediate, completing the reaction.

Created	Updated
2002-07-04	2009-02-26