Evolutionary and structural aspects of Solanaceae RNases T2

Area of Science:

• Plant molecular biology
• Biochemistry
• Evolutionary biology

Background:

• Plant Ribonucleases T2 (RNases T2) are vital enzymes regulating diverse physiological and developmental processes.
• These processes include nutrient starvation, senescence, pathogen defense, and reproductive self-incompatibility.
• Solanaceae family RNases are classified into three main clades: S-RNases and two clades of S-like RNases.

Purpose of the Study:

• To investigate the evolutionary pressures and structural variations in plant RNases T2.
• To understand how amino acid differences in S-RNases and S-like RNases relate to their functions.

Main Methods:

• Comparative analysis of amino acid sequences to identify positively selected sites.
• Structural analysis focusing on flexible regions and substrate-binding sites.

Main Results:

• Identified several positively selected amino acids in flexible regions of S-RNases and S-like RNases.
• Highlighted differences in substrate-binding site flexibility between S-RNases and S-like RNases.
• Observed specific flexible sites in S-like RNase NT (Tyr156, Asn134) potentially involved in pathogen interactions.

Conclusions:

• Differential selective pressures drive amino acid variability in plant RNases T2.
• Structural variations, particularly in flexible substrate-binding regions, are crucial for the distinct functions of S-RNases and S-like RNases.
• These variations likely facilitate diverse RNA-binding interactions, including responses to viral infections.