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Association of the class V myosin Myo4p with a localised messenger RNA in budding yeast depends on She proteins
S Münchow1, C Sauter, R P Jansen
1ZMBH, University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
Abstract:
Asymmetric distribution of messenger RNAs is a widespread mechanism to localize synthesis of specific protein to distinct sites in the cell. Although not proven yet there is considerable evidence that mRNA localisation is an active process that depends on the activity of cytoskeletal motor proteins. To date, the only motor protein with a specific role in mRNA localisation is the budding yeast type V myosin Myo4p. Myo4p is required for the localisation of ASH1 mRNA, encoding a transcriptional repressor that is essential for differential expression of the HO gene and mating type switching in budding yeast. Mutations in Myo4p, in proteins of the actin cytoskeleton, and in four other specific genes, SHE2-SHE5 disrupt the daughter-specific localisation of ASH1 mRNA. In order to understand if Myo4p is directly participating in mRNA transport, we used in situ colocalisation and coprecipitation of Myo4p and ASH1 mRNA to test for their interaction. Our results indicate an association of Myo4p and ASH1 mRNA that depends on the activity of two other genes involved in ASH1 mRNA localisation, SHE2 and SHE3. This strongly suggests a direct role of Myo4p myosin as a transporter of localised mRNAs, convincingly supporting the concept of motor-protein based mRNA localisation.
Insights
Budding yeast myosin Myo4p directly transports ASH1 messenger RNA (mRNA) to daughter cells. This motor protein interaction, dependent on SHE2 and SHE3 genes, confirms active mRNA localization via cytoskeletal motors.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Asymmetric messenger RNA (mRNA) distribution is crucial for localized protein synthesis.
- Cytoskeletal motor proteins are implicated in active mRNA localization processes.
- Budding yeast type V myosin, Myo4p, is known to be involved in mRNA localization.
Purpose of the Study:
- To investigate the direct interaction between Myo4p and ASH1 mRNA.
- To determine if Myo4p functions as a direct transporter of localized mRNAs.
Main Methods:
- In situ colocalization assays were performed to observe Myo4p and ASH1 mRNA proximity.
- Coprecipitation experiments were utilized to assess the physical association between Myo4p and ASH1 mRNA.
- The role of SHE2 and SHE3 genes in this interaction was examined.
Main Results:
- Myo4p was found to associate with ASH1 mRNA.
- This association was dependent on the activity of the SHE2 and SHE3 genes.
- Evidence strongly suggests Myo4p directly interacts with and transports ASH1 mRNA.
Conclusions:
- Myo4p functions as a direct transporter of localized mRNAs, specifically ASH1 mRNA in budding yeast.
- This study provides convincing support for the model of motor-protein-based mRNA localization.
- The findings highlight the importance of cytoskeletal motor proteins in cellular asymmetry and gene regulation.