Glycerol 3-phosphate Cytidylyltransferase

Ashley Mericle

Sequence

Overall Structure

Structure

• 5 parallel β sheets• α-helices pack next to the sheets

– Form α/β supersecondary structure• 310

helices connect the β sheets

Function

• Teichoic acids are major componenets of the cell walls of most Gram-positive bacteria. The genes concerned with the synthesis of poly(glycerol phosphate) are organized into two operons. The gene of the tagDEF operon, tagD, encodes glycerol-3-phosphate cytidylyltransferase.

• It catalyzes the transfer of the cytidyl group of CTP to glycerol phosphate.

Teichoic Acid Production Pathway

Overall Reaction

H

CH O H

COH H

C HH

P O

O-

-O

+ H O P

O

O-

O P O P O

O O

O- O-O

N

N

N

O

H H

O O HH

H

CH O H

COH H

CH

H

O P O P O

O O

O- O-O

N

N

N

O

H H

O O HH

Vmax : 55.1 ± 8.3 μmol/min/mgKm: 1.4 ± 0.1

Glycerol 3-phosphate Cytidine 5’-triphosphate (CTP) Cytidine diphosphoglycerol (CDP-glycerol)

Important Amino Acids• Lysine 44• Lysine 46

Dimer Interface

• Arginine 63 is buried– From one of the conserved

sequences

• Tryptophan 15• Leucine12 and Leucine 13 – hydrophobic

Interface Amino Acids• Leucine 12• Leucine 13• Tryptophan 15

Helical Wheels of Interface Helices

Active Site

• Residues that interact with CTP do not extend across the dimer interface. – This suggests each chain possesses its

own active site– There is the possibility for interaction

between them due to the conserved residues

– The active site is shaped like a bowl and is open to solvent at its top.

Active Site

Sequence Alignment

Conserved Residues•GX(Y/F)DXXHXGH•RTXGISTT•RYVDEVI

•The first two conserved sequences comprise one side of the active site bowl.

Medical Relevance• Some bacteria, which are

normally found in the mouth, digestive tract, urinary tract, and upper airways of the respiratory system can cause endocarditis. If the bacteria get in the bloodstream, it can get to the heart and cause inflammation in the heart lining.

• It is thought that if the reaction involving GCT can be stopped, then the production of infected heart lining can be stopped.

References

• Pattridge KA, Weber CH, Friesen JA, Sanker S, Kent C, Ludwig ML. (2003) J Biol Chem. 278, 51863-51871

• Weber CH, Park YS, Sanker S, Kent C, Ludwig ML. (1999) Structure Fold Des. 7, 1113-1124.