A highly selective oligopeptide binding protein from the archaeon Sulfolobus solfataricus

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Cell surface proteins play crucial roles in nutrient uptake and cellular interactions.
• ATP-binding cassette (ABC) transporters are essential for the translocation of various molecules across membranes.
• Oligopeptide binding proteins are involved in the recognition and transport of peptide substrates.

Purpose of the Study:

• To identify and characterize novel cell surface proteins in Sulfolobus solfataricus.
• To investigate the function and substrate specificity of the identified protein.
• To elucidate its role within a potential ABC transporter system.

Main Methods:

• Proteomics approach for cell surface protein identification.
• Genomic analysis to identify associated genes and operon structures.
• Gene expression analysis under different culture conditions.
• Protein purification and characterization (multimeric form, glycosylation).
• Oligopeptide binding assays with native and truncated protein variants.

Main Results:

• SSO1273 identified as a cell surface protein, strongly induced by peptide-rich medium.
• SSO1273 is part of an operon with ABC transporter components.
• The purified protein, OppA(Ss), is a hexameric oligopeptide binding protein.
• OppA(Ss) is an N-linked glycoprotein with specific oligopeptide binding and amino acid selectivity.
• A truncated version retained low but significant binding activity.

Conclusions:

• OppA(Ss) is a key component of a novel oligopeptide ABC transporter in Sulfolobus solfataricus.
• The protein's glycosylation and multimeric structure likely contribute to its function.
• OppA(Ss) demonstrates specific recognition of oligopeptides based on amino acid composition.