a-Factor from Saccharomyces cerevisiae: Partial Characterization of a Mating Hormone Produced by Cells of Mating Type a

1978 ◽  
Vol 133 (2) ◽  
pp. 1050-1050
1986 ◽  
Vol 6 (2) ◽  
pp. 688-702 ◽  
Author(s):  
J M Ivy ◽  
A J Klar ◽  
J B Hicks

Mating type in the yeast Saccharomyces cerevisiae is determined by the MAT (a or alpha) locus. HML and HMR, which usually contain copies of alpha and a mating type information, respectively, serve as donors in mating type interconversion and are under negative transcriptional control. Four trans-acting SIR (silent information regulator) loci are required for repression of transcription. A defect in any SIR gene results in expression of both HML and HMR. The four SIR genes were isolated from a genomic library by complementation of sir mutations in vivo. DNA blot analysis suggests that the four SIR genes share no sequence homology. RNA blots indicate that SIR2, SIR3, and SIR4 each encode one transcript and that SIR1 encodes two transcripts. Null mutations, made by replacement of the normal genomic allele with deletion-insertion mutations created in the cloned SIR genes, have a Sir- phenotype and are viable. Using the cloned genes, we showed that SIR3 at a high copy number is able to suppress mutations of SIR4. RNA blot analysis suggests that this suppression is not due to transcriptional regulation of SIR3 by SIR4; nor does any SIR4 gene transcriptionally regulate another SIR gene. Interestingly, a truncated SIR4 gene disrupts regulation of the silent mating type loci. We propose that interaction of at least the SIR3 and SIR4 gene products is involved in regulation of the silent mating type genes.


1989 ◽  
Vol 9 (6) ◽  
pp. 2536-2543
Author(s):  
J Y Lee ◽  
D R Engelke

Saccharomyces cerevisiae cellular RNase P is composed of both protein and RNA components that are essential for activity. The isolated holoenzyme contains a highly structured RNA of 369 nucleotides that has extensive sequence similarities to the 286-nucleotide RNA associated with Schizosaccharomyces pombe RNase P but bears little resemblance to the analogous RNA sequences in procaryotes or S. cerevisiae mitochondria. Even so, the predicted secondary structure of S. cerevisiae RNA is strikingly similar to the bacterial phylogenetic consensus rather than to previously predicted structures of other eucaryotic RNase P RNAs.


2004 ◽  
Vol 72 (2) ◽  
pp. 667-677 ◽  
Author(s):  
Jeremy Geiger ◽  
Deborah Wessels ◽  
Shawn R. Lockhart ◽  
David R. Soll

ABSTRACT Previous studies employing transmembrane assays suggested that Candida albicans and related species, as well as Saccharomyces cerevisiae, release chemoattractants for human polymorphonuclear leukocytes (PMNs). Because transmembrane assays do not definitively distinguish between chemokinesis and chemotaxis, single-cell chemotaxis assays were used to confirm these findings and test whether mating-type or white-opaque switching affects the release of attractant. Our results demonstrate that C. albicans, C. dubliniensis, C. tropicalis, C. parapsilosis, and C. glabrata release bona fide chemoattractants for PMNs. S. cerevisiae, however, releases a chemokinetic factor but not a chemoattractant. Characterization of the C. albicans chemoattractant revealed that it is a peptide of approximately 1 kDa. Whereas the mating type of C. albicans did not affect the release of chemoattractant, switching did. White-phase cells released chemoattractant, but opaque-phase cells did not. Since the opaque phase of C. albicans represents the mating-competent phenotype, it may be that opaque-phase cells selectively suppress the release of chemoattractant to facilitate mating.


1986 ◽  
Vol 6 (2) ◽  
pp. 688-702
Author(s):  
J M Ivy ◽  
A J Klar ◽  
J B Hicks

Mating type in the yeast Saccharomyces cerevisiae is determined by the MAT (a or alpha) locus. HML and HMR, which usually contain copies of alpha and a mating type information, respectively, serve as donors in mating type interconversion and are under negative transcriptional control. Four trans-acting SIR (silent information regulator) loci are required for repression of transcription. A defect in any SIR gene results in expression of both HML and HMR. The four SIR genes were isolated from a genomic library by complementation of sir mutations in vivo. DNA blot analysis suggests that the four SIR genes share no sequence homology. RNA blots indicate that SIR2, SIR3, and SIR4 each encode one transcript and that SIR1 encodes two transcripts. Null mutations, made by replacement of the normal genomic allele with deletion-insertion mutations created in the cloned SIR genes, have a Sir- phenotype and are viable. Using the cloned genes, we showed that SIR3 at a high copy number is able to suppress mutations of SIR4. RNA blot analysis suggests that this suppression is not due to transcriptional regulation of SIR3 by SIR4; nor does any SIR4 gene transcriptionally regulate another SIR gene. Interestingly, a truncated SIR4 gene disrupts regulation of the silent mating type loci. We propose that interaction of at least the SIR3 and SIR4 gene products is involved in regulation of the silent mating type genes.


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