Structural Analysis of a Peptide (CTLTTKLYC) that Interacts with Newcastle Disease Virus
A peptide with the sequence Cys-Thr-Leu-Thr-Thr-Lys-Leu-Tyr-Cys (CTLTTKLYC) has previously been identified to inhibit the propagation of Newcastle disease virus (NDV) in embryonated chicken eggs and tissue culture. It has two different dissociation constants (&"I), in which the first con...
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Format: | Thesis |
Language: | English |
Published: |
2005
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Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/5942/1/FBSB_2005_22%20IR.pdf |
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Summary: | A peptide with the sequence Cys-Thr-Leu-Thr-Thr-Lys-Leu-Tyr-Cys (CTLTTKLYC)
has previously been identified to inhibit the propagation of Newcastle disease virus
(NDV) in embryonated chicken eggs and tissue culture. It has two different
dissociation constants (&"I), in which the first constant can be used as a determinant
to classifjr NDV strains into two groups: the velogenic strains in the first group,
whereas the mesogenic and lentogenic strains are in the second group. The peptide,
C 1T 2L3 P T5K 6 L7 Y8 C9 ,d isplayed on the pIII protein of a filamentous M13 phage was
mutated by oligonucleotide-directed mutagenesis in order to identify the amino acid
residues involved in the interactions with NDV. Mutations of Cys at first position
(c')a nd Lys at the sixth position of the peptide ( K ~t)o Ala (A), which produced
mutants C'A and K~Ad,i d not affect the binding between the peptide and the virus
significantly, but substitution of Tyr at eighth position (Y8) alone with Ala (A)
dramatically reduced the interaction. This suggests that y8 couid play an important
role in the peptide-virus interaction. Double mutations were carried out on K~ and y8
to produce mutants K~A-Y~AK,~ R-Y~AK,~ A-Y'F, and K ~ - Y ~ Fto, determine
whether the mutated amino acids could improve the binding capability. However, the
mutations did not improve the binding capability significantly.
Fmoc-solid phase peptide synthesis was employed to synthesize the peptide,
CTLTTKLYC. Crude peptide was purified with HPLC and analysed with a mass
spectrometer. The secondary structure of the peptide was analysed with circular
dichroism (CD) and the three dimensional conformation of the peptide was
determined by nuclear magnetic resonance (NMR) and molecular modelling. A
mixture conformation of p-turn and P-sheet (intermolecular interaction) was
observed for the linear peptide by using CD. However, the three-dimensional
structure of the linear peptide could not be arrived due to the mixture of
conformation which made the sequence assignment of NMR extremely difficult. On
the other hand, the disulfide-constrained cyclic peptide, which has a more rigid
structure, exhibited only a P-turn structure. Two models were obtained: one of it
consists of a p-turn and a distorted p-turn, while the other structure is an extended
structure. |
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