9 Integrated regulation of the nitrogen-carbon interface

Abstract

Significant progress has been made in understanding the integrated regulation of nitrogen and carbon metabolism in Saccharomyces cerevisiae. A major contribution to that understanding has been identification of Tor1/2 influence on the intracellular localization of Gln3/Gat1 and Rtg1/3, the transcription factors that mediate nitrogen catabolite repression-sensitive and retrograde gene expression, respectively. This chapter discusses the three areas of investigation, which together form one of the carbon-nitrogen regulatory interfaces. (i) Nitrogen catabolite repression or NCR, the means through which cells selectively utilize good nitrogen sources in preference to those that support less good growth. (ii) Retrograde gene expression that provides the α-ketoglutarate carbon backbone of glutamate when the tricarboxylic acid cycle is inoperative. (iii) Torl/2, a master cellular regulator, reported to be the critical link connecting environmental nutritional conditions with the transcriptional responses they trigger.