Dynamics of WD-repeat containing proteins in SSU processome components

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• WD-repeat proteins are crucial components of the small subunit (SSU) processome.
• Previous studies identified t-UTP sub-complex proteins as immobilized in nucleoli.

Purpose of the Study:

• To investigate the dynamics and localization of six other WD-repeat proteins within the SSU processome in living cells.
• To understand their role in nucleolar structure and function.

Main Methods:

• Fusion of six WD-repeat proteins with green fluorescent protein (GFP).
• Live-cell imaging to observe protein dynamics and localization.
• Analysis of protein behavior under suppressed rRNA transcription conditions.

Main Results:

• The majority of UTP-B sub-complex components localize to dense fibrillar and granular regions of nucleoli.
• Suppressed rRNA transcription alters localization to cap and body regions.
• Most examined proteins exhibit low mobility, suggesting stable complex interactions, with accelerated but still slow mobility upon transcription suppression.

Conclusions:

• WD-repeat proteins, excluding WDSOF1, likely function as scaffolds or core components within nucleolar macro-protein complexes.
• Their low mobility indicates stable integration into these structures.
• Nucleolar protein dynamics are responsive to changes in rRNA transcription levels.