Tuning protein GlnB-Hs surface interaction with silicon: FTIR-ATR, AFM and XPS study.

Area of Science:

• Biochemistry
• Surface Science
• Microbiology

Background:

• The GlnB protein from Herbaspirillum seropedicae (GlnB-Hs) is crucial for regulating nitrogen, carbon, and energy metabolism.
• Understanding protein-surface interactions is vital for applications in biosensing and biomaterials.

Purpose of the Study:

• To investigate the adsorption behavior and structural conformation of GlnB-Hs on both hydrophilic and hydrophobic silicon surfaces.
• To characterize the impact of surface properties on protein structure and residue interactions.

Main Methods:

• Spin coating was used to deposit GlnB-Hs onto silicon substrates.
• Atomic Force Microscopy (AFM) was employed to visualize surface morphology and protein arrangement.
• X-ray Photoelectron Spectroscopy (XPS) analyzed the protonation states of nitrogen atoms.
• Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) assessed protein secondary structure.

Main Results:

• On hydrophilic silicon, GlnB-Hs formed globular, donut-like arrays, with deprotonated residues interacting with the silicon oxide.
• On hydrophobic silicon, GlnB-Hs adopted a side-on conformation, forming filament networks and avoiding contact with protonated residues.
• XPS confirmed differences in nitrogen protonation states between the two surfaces.
• FTIR-ATR indicated that the protein's secondary structure was largely conserved post-adsorption.

Conclusions:

• Surface hydrophilicity significantly dictates the adsorption mechanism and conformational state of GlnB-Hs.
• The observed structural changes suggest potential alterations in protein function depending on the surface environment.
• These findings provide insights into protein immobilization strategies for biotechnological applications.