Coordinated regulation of genes of different amino acid utilization pathways in yeasts

PALAVECINO MARCOS; CORREA GARCIA SUSANA; BERMUDEZ MORETTI MARIANA

Mar del Plata

Congreso; LI Reunión de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

SAIB

Yeast cells can use a variety of compounds as nitrogen source throughdifferent specific pathways. Synthesis of proteins involved in each ofthese pathways is tightly regulated. The availability of readilytransported and metabolized nitrogen sources, which are known as goodnitrogen sources, results in the strong repression of genes involved intransport and metabolism of poor ones. The utilization of poor sourcessuch as leucine, gamma-aminobutyric acid (GABA) and allantoin requires thesynthesis of pathway-specific catabolic enzymes and permeases. In thiswork we showed that the expression of the proteins responsible for theuptake and catabolism of different poor nitrogen sources occurssequentially following a certain order determined by a tight regulation.This order could promote the utilization of a given nitrogen sourcewhereas the utilization of others, which may be less useful, could bedown-regulated in some growth media. We demonstrated here that thetranscription factor Dal81 is central in the regulation that leads to thehierarchical expression of the genes studied and, consequently, in theutilization of leucine, allantoin and GABA. The mechanisms that lead tothe temporal order in the expression of genes involved in the use of poornitrogen sources also involve another transcription factors such as Leu3and Stp1.