ExPASy Proteomics Server

Accession	MF_00180
Dates	1-JUN-2001 (Created) 25-NOV-2009 (Last updated, Version 17)

Data class

Protein

Predictors

HAMAP; MF_00180; [distribution of match scores in UniProtKB];[seed alignment for MF_00180]

Names

RibB

Identifier

RIBB

Protein name

RecName: Full=3,4-dihydroxy-2-butanone 4-phosphate synthase; Short=DHBP synthase; EC=4.1.99.12;

Gene name

ribB

FUNCTION: Catalyzes the conversion of D-ribulose 5-phosphate to formate and 3,4-dihydroxy-2-butanone 4-phosphate (By similarity).

CATALYTIC ACTIVITY: D-ribulose 5-phosphate = formate + L-3,4-dihydroxybutan-2-one 4-phosphate.

COFACTOR: Binds 2 divalent metal cations per subunit. Magnesium or manganese (By similarity).

PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; 2-hydroxy-3-oxobutyl phosphate from D-ribulose 5-phosphate: step 1/1.

SUBUNIT: Homodimer (By similarity).

SIMILARITY: Belongs to the DHBP synthase family.

Pfam	PF00926; DHBP_synthase; 1;
TIGRFAMs	TIGR00506; ribB; 1;

Lyase, Magnesium, Manganese, Metal-binding, Riboflavin biosynthesis.

GO:0000287; Molecular function: magnesium ion binding.
GO:0008686; Molecular function: 3,4-dihydroxy-2-butanone-4-phosphate synthase activity.
GO:0030145; Molecular function: manganese ion binding.
GO:0009231; Biological process: riboflavin biosynthetic process.

From: RIBB_METJA (Q60364)
Key		From		To		Description		Condition		FTGroup
REGION		25		26		Substrate binding (By similarity)		R-E
REGION		161		165		Substrate binding (By similarity)		R-x-x-[HQ]-T
METAL		26		26		Magnesium or manganese 1 (By similarity)		E
METAL		26		26		Magnesium or manganese 2 (By similarity)		E
METAL		164		164		Magnesium or manganese 2 (By similarity)		H
BINDING		30		30		Substrate (By similarity)		D
BINDING		185		185		Substrate (By similarity)		E
SITE		147		147		Essential for catalytic activity (By similarity)		H
SITE		185		185		Essential for catalytic activity (By similarity)		E

Size range:	200-247 amino acids
Related UniRules:	MF_01283 (RIBBA (supersedes the current rule))
Template:	P0A7J0 (RIBB_ECOLI); Q60364 (RIBB_METJA): [Recover all]
Scope:	Bacteria Archaea
Fusion:	Nter: None; Cter: <ribA-like>
Duplicate:	None
Plasmid encoded:	in RALSO
Comments:	RibA and RibB are fused in some organisms (see MF_01283 for bifunctional RibBA). Some ribB are followed by a ribA-like domain, which does not seem to code for GTP cyclohydrolase II activity because it lacks all the residues important for activity.