Targeted deletion of genes for eukaryotic RNA-binding proteins, Rbp1 and Rbp2, in the cyanobacterium Synechococcus sp. strain PCC7942: Rbp1 is indispensable for cell growth at low temperatures

Abstract

The unicellular cyanobacterium Synechococcus sp. strains PCC6301 and PCC7942 have two homologous genes, rbp1 and rbp2, encoding small RNA-binding proteins, Rbp1 and Rbp2. In order to elucidate their function within the cell, we performed rbp gene-disruption experiments using the transformable strain PCC7942. When rbp2 was disrupted by insertion of a kanamycin-resistance gene cassette within the protein-coding region, many transformants homozygous for the mutated target gene were obtained. Though insertional inactivation of rbp1 yielded few transformants, one transformant that carried a mutated rbp1 gene was obtained which grew poorly at a low temperature. This suggests that rbp2 is not necessary for cell growth whereas rbp1 is indispensable for cell growth at low temperatures. Possible functions of the Rbp proteins are discussed.