A basic phenylalanine-rich oligo-peptide causes antibody cross-reactivity

Area of Science:

• Plant biochemistry
• Molecular plant physiology
• Protein-protein interactions

Background:

• Glycolate oxidase (GO) and ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) are crucial enzymes in plant photosynthesis and photorespiration.
• A 2 kDa phenylalanine-rich oligo-peptide (BOP) was known to bind to GO, forming GO-BOP complexes (GC).
• RubisCO was previously understood as a single species of large and small subunits.

Purpose of the Study:

• To investigate the interaction of BOP with RubisCO.
• To characterize the resulting RubisCO-BOP complexes (RCs).
• To elucidate the implications of BOP binding on protein complex formation and antibody cross-reactivity.

Main Methods:

• Two-dimensional gel electrophoresis (2-DE)
• SDS-PAGE and Western blotting
• Immunoassays and amino acid determination

Main Results:

• BOP interacts with both GO and RubisCO subunits (rbc L and rbc S).
• Multiple RubisCO-BOP complexes (RCs) with varying properties coexist in plant leaves.
• BOP can self-assemble into polymers (34.0–91.6 kDa) after dissociation from subunits.
• BOP binding minimally affects subunit molecular weights on SDS-PAGE but can cause antibody cross-reactivity.

Conclusions:

• BOP is a significant interacting partner for key photosynthetic enzymes, including RubisCO.
• The formation of diverse BOP-protein complexes influences protein behavior and detection.
• Understanding BOP interactions is critical for interpreting results involving these enzymes and antibody-based assays.