Mutations in the C-terminal domain of topoisomerase II affect meiotic function and interaction with the casein kinase 2 beta subunit.
Topoisomerase II is a major target of the protein kinase casein kinase 2 (PK CK2) in vivo. All major phosphorylation acceptor sites in the yeast enzyme are found in the C-terminal 350aa. The acceptor sites are generally clustered such that there is more than one modified Ser or Thr within a short peptide. Mutagenesis of the predicted acceptor sites have confirmed that five of the eight predicted sites are targeted in vitro and in vivo by PK CK2. Mutation to nonphosphorylatable, neutral residues provokes at most a 10% increase in mitotic doubling time. Truncation of the enzyme leaves the enzyme catalytically active, but slightly lengthens the doubling time during mitotic growth and impedes progress through meiosis. Since this could reflect the loss of interaction with an important ligand, we have examined whether the C-terminal domain of the yeast enzyme mediates interaction with the regulatory beta subunit of PK CK2, which was previously reported to bind topoisomerase II. We find that point mutation of the phospho-acceptor sites does not abrogate the interaction with a small region of PK CK2beta, while truncation at aa1276 or aa1236 does. The site of interaction within PK CK2beta does not coincide with the highly negatively charged spermine binding site.
Leroy
D
D
Chromatin Research Unit, Swiss Institute for Experimental Cancer Research (ISREC), Epalinges.
Alghisi
G C
GC
Roberts
E
E
Filhol-Cochet
O
O
Gasser
S M
SM
D000595:Amino Acid Sequence; D001483:Base Sequence; D047390:Casein Kinase II; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D004274:DNA, Recombinant; D015180:Electrophoresis, Gel, Two-Dimensional; D008540:Meiosis / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010449:Peptide Mapping; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D004274:DNA, Recombinant; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D004250:DNA Topoisomerases, Type II