MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Huang, H. L.
Right arrow Articles by Brandriss, M. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Huang, H. L.
Right arrow Articles by Brandriss, M. C.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, February 2000, p. 892-899, Vol. 20, No. 3
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

The Regulator of the Yeast Proline Utilization Pathway Is Differentially Phosphorylated in Response to the Quality of the Nitrogen Source

Hoching L. Huang and Marjorie C. Brandriss*

Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103

Received 20 August 1999/Returned for modification 27 September 1999/Accepted 1 November 1999

The proline utilization pathway in Saccharomyces cerevisiae is regulated by the Put3p transcriptional activator in response to the presence of the inducer proline and the quality of the nitrogen source in the growth medium. Put3p is constitutively bound to the promoters of its target genes, PUT1 and PUT2, under all conditions studied but activates transcription to the maximum extent only in the absence of rich nitrogen sources and in the presence of proline (i.e., when proline serves as the sole source of nitrogen). Changes in target gene expression therefore occur through changes in the activity of the DNA-bound regulator. In this report, we demonstrate by phosphatase treatment of immunoprecipitates of extracts metabolically labeled with 32P or 35S that Put3p is a phosphoprotein. Examination of Put3p isolated from cells grown on a variety of nitrogen sources showed that it was differentially phosphorylated as a function of the quality of the nitrogen source: the poorer the nitrogen source, the slower the gel migration of the phosphoforms. The presence of the inducer does not detectably alter the phosphorylation profile. Activator-defective and activator-constitutive Put3p mutants have been analyzed. One activator-defective mutant appears to be phosphorylated in a pattern similar to that of the wild type, thus separating its ability to be phosphorylated from its ability to activate transcription. Three activator-constitutive mutant proteins from cells grown on an ammonia-containing medium have a phosphorylation profile similar to that of the wild-type protein in cells grown on proline. These results demonstrate a correlation between the phosphorylation status of Put3p and its ability to activate its target genes and suggest that there are two signals, proline induction and quality of nitrogen source, impinging on Put3p that act synergistically for maximum expression of the proline utilization pathway.

* Corresponding author. Mailing address: Department of Microbiology and Molecular Genetics, Room MSB F607, UMDNJ-New Jersey Medical School, 185 S. Orange Ave., Newark, NJ 07103. Phone: (973) 972-6261. Fax: (973) 972-3644. E-mail: brandris{at}umdnj.edu.

Molecular and Cellular Biology, February 2000, p. 892-899, Vol. 20, No. 3
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.