Identification of the bud emergence gene BEM4 and its interactions with rho-type GTPases in Saccharomyces cerevisiae.
The Rho-type GTPase Cdc42p is required for cell polarization and bud emergence in Saccharomyces cerevisiae. To identify genes whose functions are linked to CDC42, we screened for (i) multicopy suppressors of a Ts- cdc42 mutant, (ii) mutants that require multiple copies of CDC42 for survival, and (iii) mutations that display synthetic lethality with a partial-loss-of-function allele of CDC24, which encodes a guanine nucleotide exchange factor for Cdc42p. In all three screens, we identified a new gene, BEM4. Cells from which BEM4 was deleted were inviable at 37 degrees C. These cells became unbudded, large, and round, consistent with a model in which Bem4p acts together with Cdc42p in polarity establishment and bud emergence. In some strains, the ability of CDC42 to serve as a multicopy suppressor of the Ts- growth defect of deltabem4 cells required co-overexpression of Rho1p, which is an essential Rho-type GTPase necessary for cell wall integrity. This finding suggests that Bem4p also affects Rho1p function. Bem4p displayed two-hybrid interactions with Cdc42p, Rho1p, and two of the three other known yeast Rho-type GTPases, suggesting that Bem4p can interact with multiple Rho-type GTPases. Models for the role of Bem4p include that it serves as a chaperone or modulates the interaction of these GTPases with one or more of their targets or regulators.
Mack
D
D
Department of Biology, Indiana University, Bloomington 47405, USA.
Nishimura
K
K
Dennehey
B K
BK
Arbogast
T
T
Parkinson
J
J
Toh-e
A
A
Pringle
J R
JR
Bender
A
A
Matsui
Y
Y
D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism / Q000502:physiology; D017931:DNA Primers / Q000737:chemistry; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D016153:Genes, Suppressor; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020741:rho GTP-Binding Proteins
C100926:BEM4 protein, S cerevisiae; C073594:CDC24 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins; C051302:RHO1 protein, S cerevisiae; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D020741:rho GTP-Binding Proteins