SMART: Bgal_small_N domain annotation

Bgal_small_N Beta galactosidase small chain

SMART accession number:	SM01038
Description:	This domain comprises the small chain of dimeric beta-galactosidases EC:3.2.1.23. This domain is also found in single chain beta-galactosidase.
Interpro abstract (IPR004199):	This domain comprises the small chain of dimeric beta-galactosidases EC 3.2.1.23. This domain is also found in single chain beta-galactosidase, which is comprised of five domains, where it represents domain 5. It contains an N-terminal loop that swings towards the active site upon the deep binding of a ligand to produce a closed conformation [(PUBMED:11732897)].
GO process:	carbohydrate metabolic process (GO:0005975)
GO component:	beta-galactosidase complex (GO:0009341)
GO function:	beta-galactosidase activity (GO:0004565)
Family alignment:	View or

There are 943 Bgal_small_N domains in 943 proteins in SMART's nrdb database.

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Evolution (species in which this domain is found)
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Go to specific node: Arabidopsis thaliana
Cellular role (predicted cellular role)
Cellular role: metabolism
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
- Juers DH et al.
- A structural view of the action of Escherichia coli (lacZ)beta-galactosidase.
- Biochemistry. 2001; 40: 14781-94
- Display abstract
- The structures of a series of complexes designed to mimic intermediatesalong the reaction coordinate for beta-galactosidase are presented. Thesecomplexes clarify and enhance previous proposals regarding the catalyticmechanism. The nucleophile, Glu537, is seen to covalently bind to thegalactosyl moiety. Of the two potential acids, Mg(2+) and Glu461, thelatter is in better position to directly assist in leaving groupdeparture, suggesting that the metal ion acts in a secondary role. Asodium ion plays a part in substrate binding by directly ligating thegalactosyl 6-hydroxyl. The proposed reaction coordinate involves themovement of the galactosyl moiety deep into the active site pocket. Forthose ligands that do bind deeply there is an associated conformationalchange in which residues within loop 794-804 move up to 10 A closer to thesite of binding. In some cases this can be inhibited by the binding ofadditional ligands. The resulting restricted access to the intermediatehelps to explain why allolactose, the natural inducer for the lac operon,is the preferred product of transglycosylation.
Structure (3D structures containing this domain)

3D Structures of Bgal_small_N domains in PDB

PDB code	Main view	Title
1bgl		Beta-galactosidase (chains a-h)
1bgm		Beta-galactosidase (chains i-p)
1dp0		E. coli beta-galactosidase at 1.7 angstrom
1f49		E. coli (lac z) beta-galactosidase (ncs constrained monomer- monoclinic)
1f4a		E. coli (lacz) beta-galactosidase (ncs constrained monomer- orthorhombic)
1f4h		E. coli (lacz) beta-galactosidase (orthorhombic)
1gho		E. coli (lac z) beta-galactosidase (ncs constrained monomer- monoclinic)
1hn1		E. coli (lac z) beta-galactosidase (orthorhombic)
1jyn		E. coli (lacz) beta-galactosidase (e537q) in complex with lactose
1jyv		E. coli (lacz) beta-galactosidase (e537q) in complex with onpg
1jyw		E. coli (lacz) beta-galactosidase (e537q) in complex with pnpg
1jyx		E. coli (lacz) beta-galactosidase in complex with iptg
1jyy		E. coli (lacz) beta-galactosidase in complex with 2-f- lactose. chains a-h, see remark 400.
1jyz		E. coli (lacz) beta-galactosidase in complex with 2-f- lactose. chains i-p, see remark 400.
1jz0		E. coli (lacz) beta-galactosidase-trapped 2-f-galactosyl- enzyme intermediate. chains a-h, see remark 400
1jz1		E. coli (lacz) beta-galactosidase-trapped 2-f-galactosyl- enzyme intermediate. chains i-p, see remark 400
1jz2		E. coli (lacz) beta-galactosidase-trapped 2-f-galactosyl- enzyme intermediate (orthorhombic)
1jz3		E. coli (lacz) beta-galactosidase-trapped 2-deoxy- galactosyl enzyme intermediate
1jz4		E. coli (lacz) beta-galactosidase-trapped 2-deoxy- galactosyl-enzyme intermediate (low bis-tris)
1jz5		E. coli (lacz) beta-galactosidase in complex with d- galctopyranosyl-1-on
1jz6		E. coli (lacz) beta-galactosidase in complex with galacto- tetrazole
1jz7		E. coli (lacz) beta-galactosidase in complex with galactose
1jz8		E. coli (lacz) beta-galactosidase (e537q) in complex with allolactose
1px3		E. coli (lacz) beta-galactosidase (g794a)
1px4		E. coli (lacz) beta-galactosidase (g794a) with iptg bound
1yq2		Beta-galactosidase from arthrobacter sp. c2-2 (isoenzyme c2- 2-1)
3bga		Crystal structure of beta-galactosidase from bacteroides thetaiotaomicron vpi-5482
3czj		"e. coli (lacz) beta-galactosidase (n460t) in complex with d-galctopyranosyl-1-one"
3dec		Crystal structure of a glycosyl hydrolases family 2 protein from bacteroides thetaiotaomicron
3dym		E. coli (lacz) beta-galactosidase (h418e)
3dyo		E. coli (lacz) beta-galactosidase (h418n) in complex with iptg
3dyp		E. coli (lacz) beta-galactosidase (h418n)
3e1f		"e.coli (lacz) beta-galactosidase (h418e) in complex with galactose"

Links (links to other resources describing this domain)
PFAM Bgal_small_N
INTERPRO IPR004199

PFAM	Bgal_small_N
INTERPRO	IPR004199