Transcript GCT - Illinois State University

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
H
N
H
H
H
C
O
O
C
H
H
C
H
-O
P
O
N
H
O
+
H O P
O-
O
O
P
O-
H
O
O
P
N
O
O
H
O-
O
C
O
H
O
C
H
O
H
C
O
P
H
Glycerol 3-phosphate
O
O
H
Cytidine 5’-triphosphate (CTP)
N
H
OH
H
H
N
O-
N
O
O
P
O
O
O
O-
H
O
O
H
Cytidine diphosphoglycerol (CDP-glycerol)
Vmax : 55.1 ± 8.3 μmol/min/mg
Km: 1.4 ± 0.1
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.