High impact information on DDI1

• RAD23 and DDI1 suppress the temperature and hydroxyurea, but not radiation or nocodazole, sensitivity of pds1-128. rad23 and ddi1 mutants are partially defective in S-phase checkpoint control but are proficient in DNA damage and spindle assembly checkpoints [1].
• On the basis of these results, we propose that Vsm1 is a novel v-SNARE-interacting protein that appears to act as negative regulator of constitutive exocytosis [2].
• Yeast VSM1 encodes a v-SNARE binding protein that may act as a negative regulator of constitutive exocytosis [2].
• Importantly, Vsm1 binding to Sso seems to preclude Sso binding to its partner t-SNARE, Sec9, and vice versa [3].
• Phosphorylation of Sso increases its affinity for Vsm1 by more than fivefold in vitro and both phosphorylated Sso1, as well as Sso1 bearing an aspartate substitution at position 79, interact tightly with Vsm1 [3].

Biological context of DDI1

• Two alternative cell cycle checkpoint pathways differentially control DNA damage-dependent induction of MAG1 and DDI1 expression in yeast [4].
• MAG1 and DDI1 are transcribed from a common promoter region and co-induced by a variety of DNA damaging agents [5].
• Like MAG1, the DDI1 gene is also controlled by an upstream repressing site (URS) located 5' to the direct repeat [6].
• Deletions, or point mutations, within this repeat completely abolished DNA-damage induction and resulted in a reduced basal-level expression for both MAG1 and DDI1 genes [6].
• UAS(MAG1), a yeast cis-acting element that regulates the expression of MAG1, is located within the protein coding region of DDI1 [7].

Associations of DDI1 with chemical compounds

• Furthermore, MAG1 and DDI1 respond differently in the presence of the protein synthesis inhibitor cycloheximide, suggesting that these two genes are regulated by different mechanisms in the absence of de novo protein synthesis [7].
• The substitution of serine-79 in Sso1 with an alanine residue or the treatment of yeast with C2-ceramide, which results in the dephosphorylation of serine-79, both inhibit Vsm1 binding in vivo [3].
• Vsm1 binding is dependent upon the NH2-terminal autoinhibitory domain of Sso, and constitutively "open" forms of the t-SNARE show a reduction in Vsm1 binding in vivo [3].

Other interactions of DDI1

• The Saccharomyces cerevisiae genes RAD23 and DDI1 were identified in a screen for multicopy suppressors of the temperature-sensitivity of a mutant allele of S. cerevisiae PDS1 [8].
• In order to understand how damage checkpoints control the expression of DNA damage-inducible genes, the transcript level of two closely clustered genes, MAG1 and DDI1, was examined in a number of checkpoint mutants [4].
• Pdr3 is required for DNA damage induction of MAG1 and DDI1 via a bi-directional promoter element [9].

References