Literature summary for 5.5.1.B6 extracted from

Kallio, P.; Sultana, A.; Niemi, J.; Maentsaelae, P.; Schneider, G.
Crystal structure of the polyketide cyclase AknH with bound substrate and product analogue: implications for catalytic mechanism and product stereoselectivity (2006), J. Mol. Biol., 357, 210-220.

Cloned(Commentary)

Cloned (Comment)	Organism
expression in Escherichia coli	Streptomyces galilaeus

Crystallization (Commentary)

Crystallization (Comment)	Organism
AknH forms a tetramer of 222 symmetry. Two subunits (A-B and C-D, respectively), related by one of the 2-fold symmetry axes, form tight dimer interfaces. The side-chains of Thr128, Gln105 and the main-chain nitrogen of Val92 each interact with oxygen atoms of the polyketide core of the product via a water molecule. Additional enzyme-ligand interactions involve residues Arg120 and Trp122 from the other monomer across the subunit-subunit interface	Streptomyces galilaeus

Crystallization (Comment)

Organism

AknH forms a tetramer of 222 symmetry. Two subunits (A-B and C-D, respectively), related by one of the 2-fold symmetry axes, form tight dimer interfaces. The side-chains of Thr128, Gln105 and the main-chain nitrogen of Val92 each interact with oxygen atoms of the polyketide core of the product via a water molecule. Additional enzyme-ligand interactions involve residues Arg120 and Trp122 from the other monomer across the subunit-subunit interface

Streptomyces galilaeus

Protein Variants

Protein Variants	Comment	Organism
D121A	0.2% of wild-type activity, (R)-configuration at C9 of product	Streptomyces galilaeus
H107A	2% of wild-type activity, (R)-configuration at C9 of product	Streptomyces galilaeus
N51L	exchange to corresponding residues of SnoaL, EC 5.5.1.26, producing product with (S)-configuration. 20% of wild-type activity, about 50% (S)-configuration at C9 of product	Streptomyces galilaeus
Q105A	6% of wild-type activity, (R)-configuration at C9 of product	Streptomyces galilaeus
Y15F	exchange to corresponding residues of SnoaL, EC 5.5.1.26, producing product with (S)-configuration. 45% of wild-type activity, about 20% (S)-configuration at C9 of product	Streptomyces galilaeus

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
0.002	-	nogalonic acid methyl ester	pH 7.4, temperature not specified in the publication	Streptomyces galilaeus

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
aklanonic acid methyl ester	Streptomyces galilaeus	-	?	-	?
nogalonic acid methyl ester	Streptomyces galilaeus	-	auraviketone	product has (R)-configuration at C9, ring closure is an intramolecular aldol condensation. The attack of the enol(ate) is on the si face of the C9 carbonyl group, required for the formation of the C9-R stereoisomer, which results in the alcoholate anion pointing away from the carboxyl side-chain of Asp121	?

Organism

Organism	UniProt	Comment	Textmining
Streptomyces galilaeus	O52646	-	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
aklanonic acid methyl ester	-	Streptomyces galilaeus	?	-	?
nogalonic acid methyl ester	-	Streptomyces galilaeus	auraviketone	product has (R)-configuration at C9, ring closure is an intramolecular aldol condensation. The attack of the enol(ate) is on the si face of the C9 carbonyl group, required for the formation of the C9-R stereoisomer, which results in the alcoholate anion pointing away from the carboxyl side-chain of Asp121	?

Synonyms

Synonyms	Comment	Organism
AcmA	-	Streptomyces galilaeus
aklanonic acid methyl ester cyclase	-	Streptomyces galilaeus
AknH	-	Streptomyces galilaeus

Turnover Number [1/s]

Turnover Number Minimum [1/s]	Turnover Number Maximum [1/s]	Substrate	Comment	Organism	Structure
1	-	nogalonic acid methyl ester	pH 7.4, temperature not specified in the publication	Streptomyces galilaeus

pH Optimum

pH Optimum Minimum	pH Optimum Maximum	Comment	Organism
7.2	-	-	Streptomyces galilaeus