Structural Properties of Potexvirus Coat Proteins Detected by Optical Methods
P I Semenyuk1, O V Karpova, A L Ksenofontov
1Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119991, Russia. makarovvalentine@gmail.com.
Biochemistry. Biokhimiia
|March 6, 2017
Summary
Coat protein (CP) structures in three potexviruses are similar, but circular dichroism (CD) spectroscopy reveals distinct optical properties. Differences in CD spectra correlate with disordered N-terminal segments in CPs, impacting virion structure and biological activity.
Area of Science:
- Plant Virology
- Structural Biology
- Biophysics
Background:
- Potexviruses are flexible, helical, RNA-containing plant viruses with coat proteins (CPs).
- X-ray analysis shows similar alpha-helical structures in the cores of potexvirus CPs.
- Structural lability of potexvirus virions is crucial for biological activity but not explained by CP core similarity.
Purpose of the Study:
- To compare the optical properties of CPs from three potexviruses (AltMV, PAMV, PVX) using circular dichroism (CD) spectroscopy.
- To investigate the relationship between CP structure, virion optical properties, and potential disordered regions.
Main Methods:
- Circular dichroism (CD) spectroscopy in the far UV region was used to analyze CPs from Alternanthera mosaic virus (AltMV), potato aucuba mosaic virus (PAMV), and potato virus X (PVX).
- Studies were conducted on CPs in both free state and within virions.
- Homology modeling based on known potexvirus CP structures was employed, alongside amino acid sequence comparison and prediction of disordered regions.
Main Results:
- CD spectra of AltMV virions were similar to papaya mosaic virus (PapMV) virions but differed significantly from PAMV virions.
- PAMV virion CD spectra resembled PVX virion spectra, showing abnormally low molar ellipticity for alpha-helical proteins.
- Homology modeling confirmed near-identical structures of CP cores across AltMV, PAMV, and PVX.
- A correlation was found between virion CD spectral features and the presence of disordered N-terminal segments in the CPs.
Conclusions:
- Despite similar alpha-helical CP core structures, potexviruses exhibit distinct virion optical properties detectable by CD spectroscopy.
- Disordered N-terminal segments in CPs likely contribute to the observed differences in virion structure and optical properties.
- These findings suggest a link between CP N-terminal region flexibility and potexvirus virion lability and biological activity.
