The yeast phosphofructokinase β-subunit has RNA unwinding activity and modulates cell cycle progression

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Phosphofructokinase (PFK) is a key glycolytic enzyme.
• PFK subunits possess an uncharacterized RNA-binding activity.

Purpose of the Study:

• To investigate the RNA-binding capabilities of yeast PFK subunits.
• To elucidate the functional implications of PFK's RNA-binding activity in cell cycle regulation.

Main Methods:

• Messenger RNA (mRNA) immunoprecipitation assays.
• RNA motif analysis.
• In vitro RNA unwinding assays.
• Ribosome association studies.
• Analysis of yeast mutant phenotypes (cell size, cell cycle progression).

Main Results:

• Yeast PFK subunits (Pfk1p and Pfk2p) bind hundreds of functionally related mRNAs, including those involved in mitotic cell cycle control.
• Both subunits recognize GA-, UC-, AU-, and U-rich motifs on their mRNA targets.
• Pfk2p exhibits 5'-3' double-stranded RNA unwinding activity, unlike Pfk1p.
• Pfk2p associates with ribosomes and enhances the translation of cell cycle genes.
• Mutants lacking Pfk2p (pfk2∆) show increased cell size and delayed G1/S phase transition, independent of glycolytic function.

Conclusions:

• The yeast PFK Pfk2 subunit functions as a translational activator of mitotic cell cycle transcripts.
• This activation is possibly mediated by energy-dependent RNA unwinding activity.
• These findings reveal a novel link between central energy metabolism and cell proliferation control.