Many species of cyanobacteria possess genes whose products contain an RNP motif that is highly similar to that found in the RNP family of eukaryotic RNA-binding proteins. The rbpA gene, one of two RNA-binding protein genes in Synechococcus sp. PCC 7942, codes for a protein of 107 amino acids with a single RNA Recognition Motif (RRM) and a short (23 aa) auxiliary domain containing 15 glycine residues. Mutation of rbpA by insertional inactivation using the Sm/Sp resistance omega cassette resulted in a reduction in doubling time and an alteration of the whole cell spectrum when compared with the wild type organism. This phenotype was not observed in a "control mutant" in which the omega cassette was inserted outside the rbpA gene. We were unable to rescue the mutant phenotype by insertion of a copy of the rbpA gene into a neutral site in the cyanobacterial genome. However, the I)NA fragment cloned in the neutral site did not include a palindromic sequence located in the 3' untranslated region of the gene. We think that this sequence may" play a role in expression of the gene; we are currently testing this hypothesis. The function of :yanobacteriaJ RNA-binding proteins is not known. Our preliminary findings suggest that the RbpA protein may affect the content of the phycobilisome :omponents of the photosynthetic apparatus. The nature or identity of the RNA molecules that are bound by these proteins is also not known: binding tudies to identify specific RNA sequences which inay bind to this protein re underway. (Research supported by the Natural Sciences and Engineering Research Council of Canada).
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology