Peptidoglycan glycosyltransferase () is an
enzyme used in the
biosynthesis
Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. ...
of
peptidoglycan. It transfers a disaccharide-peptide from a donor substrate to synthesize a
glycan
The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate p ...
chain.
This enzyme belongs to the family of
glycosyltransferases, specifically the hexosyltransferases. The
systematic name of this enzyme class is undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-(1->4)-(N-acetyl-D-mu ramoylpentapeptide):undecaprenyldiphospho-(N-acetyl-D-glucosaminyl-( 1->4)-N-acetyl-D-muramoylpentapeptide) disaccharidetransferase. Other names in common use include PG-II, bactoprenyldiphospho-N-acetylmuramoyl-(N-acetyl-D-glucosaminyl)-, pentapeptide:peptidoglycan, N-acetylmuramoyl-N-acetyl-D-glucosaminyltransferase, penicillin binding protein (3 or 1B), and peptidoglycan transglycosylase.
Function
Peptidoglycan glycosyltransferase couples Lipid II subunits to synthesize the peptidoglycan chains.
Transpeptidases crosslink the carbohydrate chains to provide the framework for the cell wall.
It
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
the
chemical reaction
:
lcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol + GlcNAc-(1->4)-Mur
2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol
: ⇌
:
lcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)+1- diphosphoundecaprenol + undecaprenyl diphosphate
The 2
substrates of this enzyme are
*
lcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol,
* GlcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)-diphosphoundecaprenol,
whereas its 2
products are
*
lcNAc-(1->4)-Mur2Ac(oyl-L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala)+1-diphosphoundecaprenol, and
*
undecaprenyl diphosphate
C55-isoprenyl pyrophosphate (undecaprenyl pyrophosphate; C55-PP) is an essential molecule involved in construction of the bacterial peptidoglycan cell wall. It is a receptor found in the plasma membrane of bacteria that allows glycan tetrapeptid ...
.
Structural studies
As of late 2007, 3
structures have been solved for this class of enzymes, with
PDB accession codes , , and .
References
*
EC 2.4.1
Enzymes of known structure
{{2.4-enzyme-stub