RHO1 (YlRHO1) is a non-essential gene in Yarrowia lipolytica and complements rho1Δ lethality in Saccharomyces cerevisiae

The synthesis of beta-1,3-glucan, the structural component of the yeast cell wall that gives shape to the cell, occurs at the plasma membrane and is the result of the activity of at least a two-component complex. Fks1p is the catalytic subunit directly responsible for the synthesis of beta-1,3-glucan, whilst the second subunit, Rho1p, has a GTP-dependent regulatory role (Yamochi et al., 1994). RHO1 has been characterized in Saccharomyces cerevisiae (Yamochi et al., 1994), and in several other fungal species. In this work, we have used degenerate oligonucleotides derived from the conserved regions of Rho1ps to isolate the RHO1 gene of Yarrowia lipolytica. The gene isolated in this way, which we have named YlRHO1, encodes a 204 amino acid protein that shows a high degree of homology with other Rho1ps. However, unlike S. cerevisiae, the ylrho1 Delta disruptant strain in Y. lipolytica is viable, although it exhibits an increased sensitivity to Calcofluor white and Congo red. Also, YlRHO1 complements rho1 lethality in S. cerevisiae at both 28degreesC and 37degreesC. The complete sequence of YlRHO1 can be obtained from GenBank under Accession No. AF279915. Copyright (C) 2003 John Wiley Sons, Ltd.