DB code: S00852

RLCP classification	4.1034.143290.135 : Addition
RLCP classification	8.113.46500.4 : Isomerization
CATH domain	2.130.10.10 : Methylamine Dehydrogenase; Chain H	Catalytic domain
E.C.	5.5.1.5
CSA	1jof
M-CSA	1jof
MACiE

CATH domain	Related DB codes (homologues)
2.130.10.10 : Methylamine Dehydrogenase; Chain H	D00039 M00329

Uniprot Enzyme Name
UniprotKB	Protein name	Synonyms	RefSeq	Pfam
P38677	Carboxy-cis,cis-muconate cyclase	EC 5.5.1.5 3-carboxy-cis,cis-muconate lactonizing enzyme CMLE	XP_957686.1 (Protein) XM_952593.1 (DNA/RNA sequence)	PF10282 (Lactonase) [Graphical View]

KEGG enzyme name
Carboxy-cis,cis-muconate cyclase 3-Carboxymuconate cyclase

UniprotKB: Accession Number	Entry name	Activity	Subunit	Subcellular location	Cofactor
P38677	CMLE_NEUCR	3-Carboxy-2,5-dihydro-5-oxofuran-2-acetate = 3-carboxy-cis,cis-muconate.	Homotetramer.		Does not require divalent cations for activity.

KEGG Pathways
Map code	Pathways	E.C.
MAP00362	Benzoate degradation via hydroxylation

Compound table
	Substrates	Products	Intermediates
KEGG-id	C01163	C04553	I00068
E.C.
Compound	3-Carboxy-cis,cis-muconate	3-Carboxy-2,5-dihydro-5-oxofuran-2-acetate	3-carboxy-2,5-dihydro-5-oxofuran-2-enolate
Type	carboxyl group	carboxyl group,aromatic ring (with hetero atoms other than nitrogen atoms)
ChEBI	15749 15749	16989 16989
PubChem	5280404 5280404	440383 440383

1jofA00	Unbound	Unbound	Unbound
1jofB00	Unbound	Unbound	Unbound
1jofC00	Unbound	Unbound	Unbound
1jofD00	Unbound	Unbound	Unbound
1jofE00	Unbound	Unbound	Unbound
1jofF00	Unbound	Unbound	Unbound
1jofG00	Unbound	Unbound	Unbound
1jofH00	Unbound	Unbound	Unbound

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

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

1jofA00	HIS 148;ARG 196;GLU 212;ARG 274
1jofB00	HIS 148;ARG 196;GLU 212;ARG 274
1jofC00	HIS 148;ARG 196;GLU 212;ARG 274
1jofD00	HIS 148;ARG 196;GLU 212;ARG 274
1jofE00	HIS 148;ARG 196;GLU 212;ARG 274
1jofF00	HIS 148;ARG 196;GLU 212;ARG 274
1jofG00	HIS 148;ARG 196;GLU 212;ARG 274
1jofH00	HIS 148;ARG 196;GLU 212;ARG 274

References for Catalytic Mechanism
References	Sections	No. of steps in catalysis
[4]	Fig.3, p.488

References
[1]
Resource
Comments
Medline ID
PubMed ID	8132467
Journal	J Bacteriol
Year	1994
Volume	176
Pages	1718-28
Authors	Mazur P, Henzel WJ, Mattoo S, Kozarich JW
Title	3-Carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa: an alternate cycloisomerase motif.
Related PDB
Related UniProtKB
[2]
Resource
Comments
Medline ID
PubMed ID	15299752
Journal	Acta Crystallogr D Biol Crystallogr
Year	1996
Volume	52
Pages	221-3
Authors	Glumoff T, Helin S, Mazur P, Kozarich JW, Goldman A
Title	Crystallization and preliminary crystallographic analysis of 3-carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa.
Related PDB
Related UniProtKB
[3]
Resource
Comments
Medline ID
PubMed ID	11976482
Journal	Acta Crystallogr D Biol Crystallogr
Year	2002
Volume	58
Pages	727-34
Authors	Merckel MC, Kajander T, Deacon AM, Thompson A, Grossmann JG, Kalkkinen N, Goldman A
Title	3-Carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa: MAD phasing with 80 selenomethionines.
Related PDB
Related UniProtKB
[4]
Resource
Comments
Medline ID
PubMed ID	11937053
Journal	Structure
Year	2002
Volume	10
Pages	483-92
Authors	Kajander T, Merckel MC, Thompson A, Deacon AM, Mazur P, Kozarich JW, Goldman A
Title	The structure of Neurospora crassa 3-carboxy-cis,cis-muconate lactonizing enzyme, a beta propeller cycloisomerase.
Related PDB	1jof
Related UniProtKB

Comments
According to the literature [3] and [4], the muconate lactonizing enzymes (MLEs) convert cis,cis-muconates into muconolactones, as a part of the beta-ketoadipate pathway. This pathway consists of two branches, catechol (MLEs; E.C. 5.5.1.1) and protocatechuate (3-carboxy-cis,cis-MLEs or CMLEs; E.C. 5.5.1.2) (see [3] and [4]). Moreover, MLEs can be classified into three evolutionarily distinct classes (see [3] and [4]). Firstly, bacterial MLEs catalyze a syn addition, using a Mn2+ cofactor with a TIM barrel fold as the catalitic domain (D00282 in EzCatDB). Secondly, bacterial CMLEs (PDB;1q5n) catalyze an anti addition, without metal cofactor on a fold, which is related to class II fumarase (T00086) family (CATH 1.20.200.10). Thirdly, both eukaryotic MLEs and CMLEs catalyze a syn addition, without metal cofactor. This entry belongs to the CMLEs in the third class. According to the literature [4], this enzyme catalyzes an intramolecular addition reaction and an isomerization, through an enolate intermediate, as follows: (A) Addition of carboxylate oxygen to the C4 double-bonded carbon, forming an enolate intermediate: (A1) The sidechains of Arg196 and Arg274 seem to modulate and increase the nucleophilicity of the C1 carboxylate of the substrate, 3-carboxylate-cis,cis-muconate, by interacting with it. (A2) The C1 carboxylate oxygen makes a nucleophilic attack on the C4 (sp2) carbon, whereas Glu212 acts as a general acid to protonate the C6 carboxylate. The reactions lead to the formation of an enolate intermediate. (B) Isomerization; Shift of double-bond position (from C=C-O to C-C=O): (B1) His148 seems to act as a general acid to protonate the C5 carbon in the enolate intermediate. (Here, Glu212 must act as a general base to deprotonate the C6 enolate oxygen. Otherwise, it must be difficult to convert the enolate intermediate to the product.) ## Although the literature [4] described His148 as a general base, it seems to act as a general acid in the forward reaction (from the substrate to product). However, it will be a genral base in the reverse reaction.

Comments

According to the literature [3] and [4], the muconate lactonizing enzymes (MLEs) convert cis,cis-muconates into muconolactones, as a part of the beta-ketoadipate pathway. This pathway consists of two branches, catechol (MLEs; E.C. 5.5.1.1) and protocatechuate (3-carboxy-cis,cis-MLEs or CMLEs; E.C. 5.5.1.2) (see [3] and [4]).
Moreover, MLEs can be classified into three evolutionarily distinct classes (see [3] and [4]). Firstly, bacterial MLEs catalyze a syn addition, using a Mn2+ cofactor with a TIM barrel fold as the catalitic domain (D00282 in EzCatDB). Secondly, bacterial CMLEs (PDB;1q5n) catalyze an anti addition, without metal cofactor on a fold, which is related to class II fumarase (T00086) family (CATH 1.20.200.10). Thirdly, both eukaryotic MLEs and CMLEs catalyze a syn addition, without metal cofactor. This entry belongs to the CMLEs in the third class.
According to the literature [4], this enzyme catalyzes an intramolecular addition reaction and an isomerization, through an enolate intermediate, as follows:
(A) Addition of carboxylate oxygen to the C4 double-bonded carbon, forming an enolate intermediate:
(A1) The sidechains of Arg196 and Arg274 seem to modulate and increase the nucleophilicity of the C1 carboxylate of the substrate, 3-carboxylate-cis,cis-muconate, by interacting with it.
(A2) The C1 carboxylate oxygen makes a nucleophilic attack on the C4 (sp2) carbon, whereas Glu212 acts as a general acid to protonate the C6 carboxylate. The reactions lead to the formation of an enolate intermediate.
(B) Isomerization; Shift of double-bond position (from C=C-O to C-C=O):
(B1) His148 seems to act as a general acid to protonate the C5 carbon in the enolate intermediate. (Here, Glu212 must act as a general base to deprotonate the C6 enolate oxygen. Otherwise, it must be difficult to convert the enolate intermediate to the product.)
## Although the literature [4] described His148 as a general base, it seems to act as a general acid in the forward reaction (from the substrate to product). However, it will be a genral base in the reverse reaction.

Created	Updated
2009-09-09	2010-08-05