Abstract
RTX toxins produced by Gram-negative bacteria contain GGXGXDXUX motif sequences for Ca2+-binding and undergo reversible conformational changes by release and rebinding of Ca2+ ions. On the other hand, RTX proteins of cyanobacteria, whose structure and intracellular localization are similar to those of RTX toxins, are non-toxic and reported to be involved in cell motility. In the case of Synechocystis sp. PCC 6803, however, expression of RTX protein Sll1951 is suppressed in the motile wild type strain (WT), while the protein is abundantly expressed in the non-motile glucose-tolerant strain (GT) (above 10% of total proteins). From these facts, the involvement of cyanobacterial RTX proteins in cell motility is unlikely to be a general feature in Cyanobacteria. In this study, sll1951 was disrupted by insertion of a transposon. Resulting changes in the phenotype are reported in the presentation.
