The Lsm1-7-Pat1 complex promotes viral RNA translation and replication by differential mechanisms

• Published in: RNA (Cambridge) Vol. 21; no. 8; pp. 1469 - 1479
• Main Authors: Jungfleisch, Jennifer, Chowdhury, Ashis, Alves-Rodrigues, Isabel, Tharun, Sundaresan, Díez, Juana
• Format: Journal Article
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 01.08.2015
• Subjects: BMV; Brome mosaic virus; Bromovirus - genetics; Bromovirus - physiology; Decapping activators; Lsm proteins; Lsm1-7; Lsm1-7-Pat1 complex; Metabolisme; Mutation; Pat1; Regulatory Sequences, Ribonucleic Acid; Replication; RNA Cap-Binding Proteins - genetics; RNA Cap-Binding Proteins - metabolism; RNA missatger; RNA virus; RNA, Messenger - metabolism; RNA, Viral - metabolism; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae - virology; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Translation; Viral Proteins - metabolism; Viral RNA; Virology - methods; Virus Replication; replication; Lsm1-7; Lsm1-7-Pat1 complex; RNA virus; Lsm proteins; translation; BMV; Pat1; viral RNA; decapping activators
• ISSN: 1355-8382; 1469-9001; 1469-9001
• DOI: 10.1261/rna.052209.115

The Lsm1-7-Pat1 complex binds to the 3′ end of cellular mRNAs and promotes 3′ end protection and 5′–3′ decay. Interestingly, this complex also specifically binds to cis -acting regulatory sequences of viral positive-strand RNA genomes promoting their translation and subsequent recruitment from translation to replication. Yet, how the Lsm1-7-Pat1 complex regulates these two processes remains elusive. Here, we show that Lsm1-7-Pat1 complex acts differentially in these processes. By using a collection of well-characterized lsm1 mutant alleles and a system that allows the replication of Brome mosaic virus (BMV) in yeast we show that the Lsm1-7-Pat1 complex integrity is essential for both, translation and recruitment. However, the intrinsic RNA-binding ability of the complex is only required for translation. Consistent with an RNA-binding-independent function of the Lsm1-7-Pat1 complex on BMV RNA recruitment, we show that the BMV 1a protein, the sole viral protein required for recruitment, interacts with this complex in an RNA-independent manner. Together, these results support a model wherein Lsm1-7-Pat1 complex binds consecutively to BMV RNA regulatory sequences and the 1a protein to promote viral RNA translation and later recruitment out of the host translation machinery to the viral replication complexes.