MOLECULAR AND GENETIC-CHARACTERIZATION OF SLC1, A PUTATIVE SACCHAROMYCES-CEREVISIAE HOMOLOG OF THE METAZOAN CYTOPLASMIC DYNEIN LIGHT-CHAIN-1

Cytoplasmic dynein is a multisubunit, microtubule-dependent motor enzy me that has been proposed to function in a variety of intracellular mo vements. As part of an effort to understand the evolution and the biol ogical roles of cytoplasmic dynein, we have identified the first non-m etazoan dynein light chain 1, SLC1, in the yeast Saccharomyces cerevis iae. The amino acid sequence of the SLC1 protein is similar to those o f the human, Drosophila and Caenorhabditis cytoplasmic dynein light ch ains 1. The SLC1 gene lies adjacent to the YAP2 (= CAD1) transcription unit. The SLC1 coding sequence is split by two introns and its mRNA i s detectable throughout the cell cycle. Tetrad analysis of heterozygot es harboring a TRP insertion in the SLC1 coding region indicate that S LC1 function is not essential for cell viability. Furthermore, we demo nstrate that double mutants, defective for SLC1 and the kinesin-relate d CIN8 genes are non-lethal. The redundancy of SLC1 function in yeast contrasts with the cell death caused by loss-of-function mutations in the dynein light chain 1 gene in Drosophila melanogaster.