Involvement of DnaK3, One of the Three DnaK Proteins of Cyanobacterium Synechococcus sp. PCC7942, in Translational Process on the Surface of the Thylakoid Membrane
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The <I>Synechococcus</I> sp. PCC7942 strain carrying a missense mutation in the peptide-binding domain of DnaK3, one of the essential <I>dnaK</I> gene products, revealed temperature-sensitive growth. We also isolated suppressor mutants of this strain. One of the suppressors was mapped in the ribosomal protein gene <I>rpl24</I> (<I>syc1876</I>), which encodes the 50S ribosomal protein L24. Subcellular localization of three DnaK proteins was determined, and the results indicated that a quantity of DnaK3 was dislocated from membrane-bound polysomes when <I>dnaK3</I> temperature-sensitive mutant was incubated at non-permissive temperatures. Furthermore, we examined the photosystem II reaction center protein D1 and detected a translational intermediate polypeptide in membrane-bound polysome fractions prepared from <I>dnaK3</I> temperature-sensitive cells grown at high temperature. These characteristic features of DnaK3 localizations and detection of D1 protein intermediate were not observed in the suppressor mutant even at high temperatures.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(7), 1592-1598, 2006-07-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry