The promoter activity of yeast genes can depend on lysine 56 (K56) acetylation 
of histone H3. This modification of H3 is performed by lysine acetylase Rtt109 
acting in concert with histone chaperone Asf1. We have examined the 
contributions of Rtt109, Asf1, and H3 K56 acetylation to nutrient regulation of 
a well-studied metabolic gene, ARG1. As expected, Rtt109, Asf1, and H3 K56 
acetylation are required for maximal transcription of ARG1 under inducing 
conditions. However, Rtt109 and Asf1 also inhibit ARG1 under repressing 
conditions. This inhibition requires Asf1 binding to H3-H4 and Rtt109 KAT 
activity, but not tail acetylation of H3-H4 or K56 acetylation of H3. These 
observations suggest the existence of a unique mechanism of transcriptional 
regulation by Rtt109. Indeed, chromatin immunoprecipitation and genetic 
interaction studies support a model in which promoter-targeted Rtt109 represses 
ARG1 by silencing a pathway of transcriptional activation that depends on ASF1. 
Collectively, our results show that ARG1 transcription intensity at its induced 
and repressed set points is controlled by different mechanisms of functional 
interplay between Rtt109 and Asf1.