Synechocystis sp. PCC 6803, a unicellular cyanobacterium, is able to utilize light energy to grow autotrophically or glucose to grow heterotrophically. It is an important model species used in the molecular genetics study of cyanobacteria. Many heat shock protein genes are found in the genome of Synechocystis sp. PCC 6803. In this thesis, some preliminary studies of heat shock protein genes are presented.
The researches and results are described in two parts:
1. Heat shock protein genes were each inserted with bacterial luciferase genes luxAB and spectinomycin resistance gene. Of the resulted mutants, some fully segregated were tested for growth at 15oC and 40oC. None of these mutations showed effects on growth of Synechocystis at these temperatures. Assays of luciferase activities in these strains at 15oC indicated that genes sll0430, sll0535 and slr0093 were transcriptionally up-regulated upon transfer of cells to 15oC.
2. The mutant of sll1384 almost completely lost phototaxis motility, and complementation with the wild type gene restored its phenotype. Electron microscopy analysis showed that the type-IV pili remained unchanged on the cell surface. It is hypothesized that sll1384-encoded protein may affect the signal transduction pathway that plays an important role in phototaxis of Synechocystis.
Key words: Synechocystis sp. PCC 6803; heat shock proteins; bacterial luciferase genes; phototaxis; sll1384.