A yeast glutamine tRNA signals nitrogen status for regulation of dimorphic growth and sporulation.
Dimorphic growth of the budding yeast Saccharomyces cerevisiae is regulated by the quality of the nitrogen supply. On a preferred nitrogen source diploid cells grow as ellipsoidal cells by using a bipolar pattern of budding, whereas on a poor nitrogen source a unipolar pattern of budding is adopted, resulting in extended pseudohyphal chains of filamentous cells. Here we report that the quality of the nitrogen source is signaled by the glutamine tRNA isoform with a 5'-CUG anticodon (tRNACUG). Mutations that alter this tRNA impair assessment of the nitrogen supply without measurably affecting protein synthesis, so that mutant cells display pseudohyphal growth even on a preferred nitrogen source. The nitrogen status for other nitrogen-responsive processes such as catabolic gene expression and sporulation also is signaled by this tRNA: mutant cells inappropriately induce the nitrogen-repressed gene CAR1 and undergo precocious sporulation in nitrogen-rich media. Therefore, in addition to its role in mRNA translation, this tRNA also transduces nitrogen signals that regulate development.
Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.
L E
LE
Murray
N
N
Rowley
I W
IW
Dawes
G C
GC
Johnston
R A
RA
Singer
D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D003062:Codon; D005656:Fungal Proteins / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012351:RNA, Transfer, Gln / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013172:Spores, Fungal; D014157:Transcription Factors / Q000378:metabolism
D003062:Codon; D005656:Fungal Proteins; D012351:RNA, Transfer, Gln; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009584:Nitrogen