Ribosomes from the blue-green alga Anabeana variabilis

Functional 70S hybrid ribosomes from blue-green algae and bacteria

Hybrid 70S ribosomes were produced by combing Anacystis nidulans and Escherichia coli 30S and 50S subunits. Both the A. nidulans 30SE. coli 50S and E. coli 30S- A. nidulans 50S hybrids were functional in synthesizing protein when tested in a standard in vitro amino acid incorporating system. Both 70S hybrids were inhibited by streptomycin but the degree of inhibition was dependent upon the source of the 30S subunit. The ability to form functional 70S ribosomes from subunits of blue-green algae and bacteria is further evidence of the procaryotic nature of blue-greens and of the functional homology of the two protein synthesizing systems.

Physiology and cytological chemistry blue-green algae

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Ribosomal ribonucleic acid and ribosomal precursor ribonucleic acid in Anacystis nidulans

The RNA of the blue-green alga Anacystis nidulans contains three ribosomal RNA species with molecular weights of 0.56x10(6), 0.9x10(6), and 1.1x10(6) if the RNA is extracted in the absence of Mg(2+). The 0.9x10(6)mol.wt. rRNA is extremely slowly labelled in (32)P-incorporation experiments. This rRNA may be a cleavage product of the 1.1x10(6)mol.wt. rRNA from the ribosomes of cells in certain physiological states (e.g. light-deficiency during growth). The cleavage of the 1.1x10(6)mol.wt. rRNA during the extraction procedure can be prevented by the addition of 10mm-MgCl(2). (32)P-pulse-labelling studies demonstrate the rapid synthesis of two ribosomal precursor RNA species. One precursor RNA migrating slightly slower than the 1.1x10(6)mol.wt. rRNA appears much less stable than the other precursor RNA, which shows the electrophoretic behaviour of the 0.7x10(6)mol.wt. rRNA. Our observations support the close relationship between bacteria and blue-green algae also with respect to rRNA maturation. The conversion of the ribosomal precursor RNA species into 0.56x10(6)- and 1.1x10(6)-mol.wt. rRNA species requires Mg(2+) in the incubation medium.