A hydrogen bond study in tobacco mosaic virus using Moessbauer spectroscopy

Area of Science:

• Biophysics
• Structural Biology
• Biochemistry

Background:

• Tobacco mosaic virus (TMV) is a well-studied plant pathogen.
• Understanding protein interactions within TMV is crucial for virology research.
• The presence of specific hydrogen bonds can significantly impact viral structure and function.

Purpose of the Study:

• To investigate a proposed hydrogen bond between Tyr 139 and Glu 22 in TMV.
• To utilize the Moessbauer method to probe the electronic environment around a specific residue.
• To provide evidence for the role of hydrogen bonding in TMV subunit interactions.

Main Methods:

• Application of the Moessbauer spectroscopy technique.
• Utilizing 129I-labeled 3,5-di-iodo-L-tyrosine as a probe nucleus.
• Comparing Moessbauer spectra of the probe in free amino acid form versus in situ within TMV.

Main Results:

• The pK value of 3,5-di-iodo-L-tyrosine at position 139 in TMV increased by 0.8 units compared to its free form.
• This observed pK shift provides strong evidence for the existence of a hydrogen bond involving the hydroxyl group of Tyr 139.
• Moessbauer parameters demonstrated high sensitivity to the local electronic configuration near the probe nucleus.

Conclusions:

• The study provides compelling evidence for a hydrogen bond between Tyr 139 and Glu 22 in TMV.
• The Moessbauer method is a powerful tool for elucidating hydrogen bonding and electronic structures in complex biological systems.
• These findings contribute to a deeper understanding of TMV's structural integrity and molecular interactions.