title: Regulation of the yeast trehalose-synthase complex by cyclic AMP-dependent phosphorylation.
abstract: BACKGROUND
  Trehalose is an important protectant in several microorganisms. In Saccharomyces cerevisiae, it is synthesized by a large complex comprising the enzymes Tps1 and Tps2 and the subunits Tps3 and Tsl1, showing an intricate metabolic control.
  
  
  METHODS
  To investigate how the trehalose biosynthesis pathway is regulated, we analyzed Tps1 and Tps2 activities as well as trehalose and trehalose-6-phosphate (T6P) contents by mass spectrometry.
  
  
  RESULTS
  Tsl1 deficiency totally abolished the increase in Tps1 activity and accumulation of trehalose in response to a heat stress, whereas absence of Tps3 only reduced Tps1 activity and trehalose synthesis. In extracts of heat stressed cells, Tps1 was inhibited by T6P and by ATP. Mg(2+) in the presence of cAMP. In contrast, cAMP-dependent phosphorylation did not inhibit Tps1 in tps3 cells, which accumulated a higher proportion of T6P after stress. Tps2 activity was not induced in a tps3 mutant.
  
  
  CONCLUSIONS
  Taken together these results suggest that Tsl1 is a decisive subunit for activity of the TPS complex since in its absence no trehalose synthesis occurred. On the other hand, Tps3 seems to be an activator of Tps2. To perform this task, Tps3 must be non-phosphorylated. To readily stop trehalose synthesis during stress recovery, Tps3 must be phosphorylated by cAMP-dependent protein kinase, decreasing Tps2 activity and, consequently, increasing the concentration of T6P which would inhibit Tps1.
  
  
  CONCLUSIONS
  A better understanding of TPS complex regulation is essential for understanding how yeast deals with stress situations and how it is able to recover when the stress is over.
authors.affiliation: Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil. Electronic address: eduardotrevisol@gmail.com.
authors.forename: Eduardo T V
authors.initials: ET
authors.lastname: Trevisol
authors.affiliation: Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil.
authors.forename: Anita D
authors.initials: AD
authors.lastname: Panek
authors.affiliation: Department of Genetics and Molecular Biology, Bioinformatics and Computational Biology Group, Federal University of Rio de Janeiro State, Brazil.
authors.forename: Joelma F
authors.initials: JF
authors.lastname: De Mesquita
authors.affiliation: Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil. Electronic address: eliscael@iq.ufrj.br.
authors.forename: Elis C A
authors.initials: EC
authors.lastname: Eleutherio
mesh_terms: D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D005964:Glucosyltransferases / Q000502:physiology*; D009097:Multienzyme Complexes / Q000502:physiology*; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology*; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D013403:Sugar Phosphates / Q000378:metabolism; D014199:Trehalose / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D013403:Sugar Phosphates; C532521:TSL1 protein, S cerevisiae; C082722:trehalose-6-phosphate; D014199:Trehalose; D000242:Cyclic AMP; D005964:Glucosyltransferases; C099692:trehalose synthase; C085814:trehalose-6-phosphate synthase-phosphatase complex; D017868:Cyclic AMP-Dependent Protein Kinases; D010744:Phosphoric Monoester Hydrolases
keywords: Phosphorylation; Ras/cAPK pathway; Saccharomyces cerevisiae; Stress response; Trehalose