Isolation and study of KlLSM4 , a <TOGGLE>Kluyveromyces lactis</TOGGLE> gene homologous to the essential gene LSM4 of <TOGGLE>Saccharomyces cerevisiae</TOGGLE><FNR HREF="FN1"></FNR><FN ID="FN1">This paper is dedicated to Franco Tato. </FN>

We have isolated the KlLSM4 gene as a multicopy suppressor of a Kluyveromyces lactis mutant which shows a rag⁻ phenotype (resistance to antimycin A on glucose). This gene is homologous to the ScLSM4 of Saccharomyces cerevisiae, which codes for an essential 187 amino acid protein containing Sm-like domains. These motifs are present in the evolutionarily conserved family of the Sm-like proteins, which are involved in a large number of cellular processes, including pre-mRNA splicing and mRNA decapping. We demonstrated that the first 72 amino acids of KlLsm4p, which contain the Sm-like domains, can restore cell viability in both K. lactis and S. cerevisiae cells lacking the wild-type protein. However, the absence of the carboxy-terminal region resulted in a remarkable loss of cell viability in the stationary phase. The KlLSM4 sequence has been deposited in the EMBL Data library under Accession No. AJ311719. Copyright © 2001 John Wiley & Sons, Ltd.