High impact information on PPQ1

• We identified SAL6, TEF4, and YDL219w, all of which likely affect nonsense suppression via alteration of the protein synthesis machinery [1].
• Three other phosphatases (Ppz1p, Ppz2p, and Sal6p) share >59% identity in their catalytic region with Glc7p. ppz1 ppz2 null mutants have no apparent growth defect on rich media [2].
• The SAL6 gene encodes a very basic 549-amino acid protein whose C-terminal catalytic region of 265 residues is 63% identical to serine/threonine PP1 phosphatases, and 66% identical to yeast PPZ1 and PPZ2 phosphatases [3].
• Physical analysis maps SAL6 to chromosome XVI between TPK2 and spt14 [3].
• The SAL6 gene has now been cloned by complementation of the increased suppression efficiency and cold sensitivity caused by sal6-1 in the presence of the omnipotent suppressor sup45 [3].

Biological context of PPQ1

• Deletion of the gene encoding PPQ1 reduces cell growth on several carbon sources, and lowers cell density in the stationary phase [4].
• High copy number plasmids containing wild-type SAL6 cause antisuppressor phenotypes in suppressor strains [3].
• These results suggest that the accuracy of protein synthesis is affected by the levels of phosphorylation of the target(s) of SAL6 [3].
• However, when sal2 and sal6 are combined together in a haploid cell they do suppress weakly [5].

Associations of PPQ1 with chemical compounds

• The sequence of a Saccharomyces cerevisiae cDNA encoding a novel 61-kDa protein serine/threonine phosphatase, termed PPQ1, is presented [4].
• They are hypersensitive to the protein synthesis inhibitors, cycloheximide and G418, implicating PPQ1 in the regulation of translation [4].
• Disruptions of the entire SAL6 gene are viable, cause a slight growth defect on glycerol medium, and produce allosuppressor phenotypes in suppressor strain backgrounds [3].

Other interactions of PPQ1

• The unusual 235 residue N-terminal extension found in SAL6, like those in the PPZ proteins, is serine-rich [3].

References