Programmed ribosomal frameshifting during PLEKHM2 mRNA decoding generates a constitutively active proteoform that...

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Programmed ribosomal frameshifting is a known mechanism, primarily in viruses, for generating protein diversity.
• Conserved frameshifting events in nuclear-encoded human genes are rare.
• The human gene PLEKHM2's function and regulation were not fully understood.

Purpose of the Study:

• To investigate a novel programmed ribosomal frameshifting event in the human gene PLEKHM2.
• To characterize the function of the protein produced by this frameshifting event.
• To determine the role of PLEKHM2 frameshifting in cardiac cell function.

Main Methods:

• Analysis of mRNA and protein products from the human PLEKHM2 gene.
• Site-directed mutagenesis to study frameshifting efficiency.
• Creation and analysis of PLEKHM2 knockout cardiomyocyte models.
• Reintroduction of both canonical and frameshifted PLEKHM2 proteins.

Main Results:

• A +1 programmed ribosomal frameshifting event was identified in the human PLEKHM2 gene, yielding an internally overlapping open reading frame (ORF).
• The frameshifted PLEKHM2 protein possesses a novel alpha-helical carboxyl-terminal domain that alleviates autoinhibition.
• This frameshift protein enables cellular localization to cell tips independently of ARL8 activation.
• Restoration of normal cardiomyocyte contractile function requires both the canonical and frameshifted PLEKHM2 proteins.

Conclusions:

• Programmed ribosomal frameshifting in PLEKHM2 is crucial for generating a functional protein variant.
• The frameshifted PLEKHM2 protein plays a vital role in regulating cardiomyocyte contractility.
• This discovery highlights the significance of frameshifting in nuclear-encoded genes for cellular processes.