Interaction of Streptococcus mutans YidC1 and YidC2 with translating and nontranslating ribosomes

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• The YidC/OxaI/Alb3 protein family facilitates integral membrane protein biogenesis across diverse organisms.
• Gram-positive bacteria possess multiple YidC paralogs, classified as YidC1 and YidC2, with distinct C-terminal tail characteristics.
• Differences in C-terminal tail length and charge between YidC1 and YidC2 suggest varied ribosome interaction capabilities.

Purpose of the Study:

• To investigate the interaction between bacterial translating ribosomes and YidC1/YidC2 proteins.
• To determine the role of C-terminal tails in YidC-ribosome and YidC-membrane protein interactions.
• To elucidate the mechanism of membrane protein insertion mediated by YidC paralogs.

Main Methods:

• Bacterial two-hybrid assays to assess YidC-ribosome interactions.
• In vitro membrane insertion assays using purified proteins and liposomes.
• Site-directed mutagenesis to delete C-terminal tails of YidC proteins.

Main Results:

• Escherichia coli ribosomes interact with both YidC1 and YidC2.
• The presence of a nascent membrane protein substrate stimulates YidC-ribosome interaction.
• Deletion of the C-terminal tail abrogates ribosome interaction and YidC-dependent membrane insertion of F1F0-ATPase subunit c.

Conclusions:

• Both YidC1 and YidC2 engage in direct interaction with bacterial ribosomes.
• The C-terminal tail is crucial for mediating YidC-ribosome association and subsequent membrane protein insertion.
• The findings suggest conserved mechanisms for membrane insertion by YidC family proteins.