Folded Alpha Helical Putative New Proteins from Apilactobacillus kunkeei

Area of Science:

• Evolutionary biology
• Structural biology
• Biophysics

Background:

• The origin and evolution of new proteins are fundamental biological questions.
• While bioinformatic analyses suggest continuous protein emergence, experimental data on novel protein structures and properties are scarce.
• Understanding the biophysical characteristics of recently evolved proteins is crucial for comprehending protein evolution.

Purpose of the Study:

• To investigate the structural and biophysical properties of putative new proteins from Apilactobacillus kunkeei.
• To determine if these novel proteins are intrinsically disordered or adopt stable conformations.
• To explore the evolutionary implications of de novo protein emergence and folding.

Main Methods:

• Phylogenetic analysis to identify novel protein candidates in Apilactobacillus kunkeei.
• Circular dichroism (CD) spectroscopy to assess secondary structure content.
• Fluorescence spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy to investigate protein folding and stability.

Main Results:

• Identified 48 putative novel open reading frames in Apilactobacillus kunkeei.
• Experimental data revealed six investigated proteins are not intrinsically disordered.
• These proteins adopt alpha-helical dominated folded states with low thermodynamic stability (0-3 kcal/mol).

Conclusions:

• Newly evolved small proteins can readily form simple, folded conformations.
• Complex protein tertiary structures may evolve through the fusion of basic secondary structure elements.
• De novo emergence of folded proteins appears to be a common event in evolution.