Characterization of MYR1, a dosage suppressor of YPT6 and RIC1 deficient mutants

• Published in: Current genetics 2008-04, Vol.53 (4), p.235-247
• Main Authors: Georgiev, Alexander, Leipus, Arunas, Olsson, Ida, Berrez, Jean-Marc, Mutvei, Ann
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Biochemistry; Biomedical and Life Sciences; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Biology; Cell Membrane - metabolism; Cell Nucleus Shape; Coiled coil; Conserved Sequence; Guanine Nucleotide Exchange Factors; GYF domain; Life Sciences; Membrane Proteins; Membrane traffic; Microbial Genetics and Genomics; Microbiology; Monomeric GTP-Binding Proteins - deficiency; Monomeric GTP-Binding Proteins - genetics; Myr1; Octoxynol; Plant Sciences; Protein Structure, Tertiary; Protein Transport - genetics; Proteomics; ras Proteins - metabolism; Research Article; Ric1; Saccharomyces; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Sequence Deletion; Signal Transduction; Solubility; Suppression, Genetic - genetics; Transcription Factors - deficiency; Transcription Factors - genetics; Yeast; Ypt6
• ISSN: 0172-8083; 1432-0983; 1432-0983
• DOI: 10.1007/s00294-008-0183-0

Membrane traffic is tightly regulated and the Rab protein family of small GTPases plays a central role in this regulation. One member of this family is the Saccharomyces cerevisae protein Ypt6. To search for new genes interacting with Ypt6-related pathways, we performed a genetic screen for high copy suppressors of ypt6Δ temperature sensitivity at 35°C. Among the suppressors, MYR1 was also able to suppress the temperature sensitive mutant lacking Ric1, a subunit of the Ypt6 guanine exchanging factor complex Ric1/Rgp1. Myr1 is characterized by a coiled coil region and a GYF domain, a protein module binding proline-rich sequences. Myr1 is able to bind membranes but is also associated with larger structures insoluble in Triton X-100. By immunofluorescence, Myr1 shows a network-like pattern as well as small foci. Overexpression of Myr1 influences nuclear envelope morphology and high levels are lethal. This lethality is rescued when the N-terminal region, containing the GYF domain, is deleted. The transcription profile of a myr1Δ strain shows effects on genes involved in nuclear migration, Ras signalling and transcription. Taken together, these results suggest that Myr1 is a novel factor linked to the secretory pathway and important cellular regulatory mechanisms.