The 14-3-3 proteins encoded by the BMH1 and BMH2 genes are essential in the yeast Saccharomyces cerevisiae and can be replaced by a plant homologue.
The 14-3-3 proteins comprise a family of highly conserved acidic proteins. Several activities have been ascribed to these proteins, including activation of tyrosine and tryptophan hydroxylases in the presence of calcium/calmodulin-dependent protein kinase II, regulation of protein kinase C, phospholipase A2 activity, stimulation of exocytosis and activation of bacterial exoenzyme S (ExoS) during ADP-ribosylation of host proteins. In addition, a plant 14-3-3 protein is present in a G-box DNA/protein-binding complex. Previously, we isolated the BMH1 gene from Saccharomyces cerevisiae encoding a putative 14-3-3 protein. Using the polymerase chain reaction method, we have isolated a second yeast gene encoding a 14-3-3 protein (BMH2). While disruption of either BMH1 or BMH2 alone had little effect, it was impossible to obtain viable cells with both genes disrupted. The cDNA encoding a plant 14-3-3 protein under the control of the inducible GAL1 promoter complemented the double disruption. Transfer of the complemented double disruptant to a medium with glucose resulted in the appearance of a high percentage of large budded cells. After prolonged incubation, these cells became enlarged with irregular buds and chains of cells defective in cell-cell separation became visible. These results suggest an essential role of the 14-3-3 proteins, possibly at a later stage of the yeast cell cycle.
van Heusden
G P
GP
Institute of Molecular Plant Sciences, Leiden University, The Netherlands.
Griffiths
D J
DJ
Ford
J C
JC
Chin-A-Woeng
T F
TF
Schrader
P A
PA
Carr
A M
AM
Steensma
H Y
HY
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016415:Sequence Alignment; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D011506:Proteins; D014446:Tyrosine 3-Monooxygenase