A protein complex is involved in Q biosynthesis.
Peter K. Gin, B. Noelle Marbois, Wayne W. Poon, Catherine F.
Clarke
Chemistry and Biochemistry, UCLA, 607 Charles E. Young, Los Angeles, CA
90095, USA
Coenzyme Q is a prenylated quinone involved in redox reactions in the
cell. The complete biosynthetic pathway of Q has not yet been
characterized although at least eight genes are required for Q
biosynthesis. Recent genetic data suggest a protein complex is involved
in Q biosynthesis in yeast. Here we show the stability of Coq3p, Coq4p,
and Coq7p depends on the presence of other Coq proteins, suggestive of a
protein complex. Detergent solubilization conditions were optimized to
release Coq polypeptides and maintain O-methyltransferase
activity. Analysis of these fractions by 2D blue native gel
electrophoresis, sucrose density gradient, and gel filtration pointed
toward an estimated 240 kDa protein complex containing Coq3p and Coq4p,
two proteins required for Q biosynthesis. Also, antibodies to Coq1p,
Coq5p, and Coq6p were generated as tools to assess their presence in the
complex. The data provide the first biochemical evidence of a protein
complex involved in Q biosynthesis.
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