Expression capable library for studies of Neisseria gonorrhoeae, version 1.0

A MultiSite Gateway™ vector set for the functional analysis of genes in the model Saccharomyces cerevisiae

Background

Recombinatorial cloning using the Gateway^TM technology has been the method of choice for high-throughput omics projects, resulting in the availability of entire ORFeomes in Gateway^TM compatible vectors. The MultiSite Gateway^TM system allows combining multiple genetic fragments such as promoter, ORF and epitope tag in one single reaction. To date, this technology has not been accessible in the yeast Saccharomyces cerevisiae, one of the most widely used experimental systems in molecular biology, due to the lack of appropriate destination vectors.

Results

Here, we present a set of three-fragment MultiSite Gateway^TM destination vectors that have been developed for gene expression in S. cerevisiae and that allow the assembly of any promoter, open reading frame, epitope tag arrangement in combination with any of four auxotrophic markers and three distinct replication mechanisms. As an example of its applicability, we used yeast three-hybrid to provide evidence for the assembly of a ternary complex of plant proteins involved in jasmonate signalling and consisting of the JAZ, NINJA and TOPLESS proteins.

Conclusion

Our vectors make MultiSite Gateway^TM cloning accessible in S. cerevisiae and implement a fast and versatile cloning method for the high-throughput functional analysis of (heterologous) proteins in one of the most widely used model organisms for molecular biology research.

New insights into chemical biology from ORFeome libraries

As the genomes of many organisms have been sequenced, a variety of global analyses, called 'omics,' have been initiated. Cloning of the set of all open reading frames encoded by the genome (ORFeome) of an organism is a major challenge, which serves as an indispensable provision before one launches into the ocean of the postgenomic world. A suitable strategy for high-throughput cloning and expression of thousands of genes is crucial to success. Recently developed systems employing site-specific or homologous recombination have made it feasible to manipulate thousands of ORFs en masse. Using these technologies, several recent studies have successfully fished biologically active small molecules and target proteins out of this bountiful ocean.

RpoH mediates the expression of some, but not all, genes induced in Neisseria gonorrhoeae adherent to epithelial cells

Neisseria gonorrhoeae (gonococcus [GC]), is highly adapted to the human host, the only known reservoir for gonococcal infection. However, since it is sexually transmitted, infection of a new host likely requires a regulatory response on the part of the gonococcus to respond to this significant change in environment. We previously showed that adherence of gonococci to epithelial cells results in changes of gene expression in the bacteria that presumably prepare them for subsequent steps in the infection process. Expression of the heat shock sigma factor gene, rpoH, was shown to be important for the invasion step, as gonococci depleted for rpoH were reduced in their ability to invade epithelial cells. Here, we show that of the genes induced in adherent gonococci, two are part of the gonococcal RpoH regulon. When RpoH is depleted, expression of these genes is no longer induced by host cell contact, indicating that RpoH is mediating the host cell induction response of these genes. One RpoH-dependent gene, NGO0376, is shown to be important for invasion of epithelial cells, consistent with earlier observations that RpoH is necessary for this step of infection. Two genes, NGO1684 and NGO0340, while greatly induced by host cell contact, were found to be RpoH independent, indicating that more than one regulator is involved in the response to host cell contact. Furthermore, NGO0340, but not NGO1684, was shown to be important for both adherence and invasion of epithelial cells, suggesting a complex regulatory network in the response of gonococci to contact with host cells.