Position-specific Asp-Lys pairing can affect signal sequence function and membrane protein topology

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Positively charged amino acids are key in determining bacterial inner membrane protein topology.
• Negatively charged residues typically have minimal impact on transmembrane orientation.
• Positively charged residues can inhibit signal sequence function, while negatively charged ones are less effective.

Purpose of the Study:

• To investigate the influence of negatively charged amino acids on the function of positively charged residues in protein translocation.
• To explore the role of charge pairing in modulating protein-membrane interactions.

Main Methods:

• Investigated the effects of specific amino acid substitutions on protein topology and signal sequence function.
• Analyzed position-dependent effects of charged residues.

Main Results:

• A negatively charged aspartic acid near a positively charged lysine attenuated the effects of the positive charge in a position-specific manner.
• This suggests that charge pairing can modulate interactions with the secretory machinery or membrane phospholipids.

Conclusions:

• Charge pairing involving negatively charged amino acids can significantly influence positively charged residue functions.
• These findings highlight the critical role of charged amino acids in protein translocation and bacterial membrane protein assembly.