Random transposon insertion in
The invention provides a method for generating a database of candidate essential genes in Staphylococcus aureus , as well as otherwise important genes that, when mutated, lead to a growth attenuated phenotype. Such genes and mutants of such genes are important for identifying antibacterial agents suitable for treating and preventing S. aureus infections. The invention includes methods for confirming the essentiality or importance of candidate genes, as well as methods for utilizing those genes to screen for new antibacterial drugs. The invention also includes the antibacterial agents identified using the disclosed methods, as well as methods of using the same for treating and preventing Staphylococcus infection.
1. A method for identifying a library of putative essential or important genes using a High Throughput Transposon Insertion Map (HTTIM) database, comprising:
a) mutagenizing a Staphylococcus genome with a transposon such that individual cells, each containing one or more transposon insertion sites that received a transposon insertion, are isolated;
b) sequencing said one or more transposon insertion sites in each individual cell so as to form a database of polynucleotide sequences of transposon insertion sites, or an HTTIM database, wherein said sequencing comprises amplification of a polynucleotide fragment containing one of said transposon insertion sites and the inserted transposon;
c) comparing said polynucleotide sequences of the transposon insertion sites with the Staphylococcus genomic sequence to identify open reading frames in said Staphylococcus genomic sequence that are not disrupted by a transposon insertion; and
d) forming a library of putative essential or important genes from said open reading frames in said Staphylococcus genomic sequence that are not disrupted by a transposon insertion.
2. The method of claim 1 , wherein said genomic sequence is from S. aureus.
3. The method of claim 1 , wherein said transposon inserts randomly into the target genome.
4. The method of claim 1 , wherein said HTTIM database comprises polynucleotide sequences of at least about 3,000 to 6,000 transposon insertion sites.
5. The method of claim 4 , wherein said HTTIM database comprises polynucleotide sequences of at least about 4,000 to 5,000 transposon insertion sites.
6. The method of claim 1 , further comprising a statistical calculation for identifying putative essential genes.
7. The method of claim 6 , wherein the statistical calculation utilizes a Bayessian statistical model.
8. The method of claim 1 , further comprising a physical mutagenesis experiment in order to verify essential genes.
9. The method of claim 8 , wherein said physical mutagenesis comprises knocking out a putative essential gene or creating a promoter swap mutant.
10. The library of putative essential or important genes identified by the method of claim 1 , wherein said library comprises at most about 500 to 1850 genes.
11. The library of putative essential genes identified by the method of claim 1 , wherein said library comprises at most about 1000 to 1400 genes.
12. The library of putative essential genes identified by the method of claim 1 , wherein said library comprises at most about 600-625 genes.
13. The library of putative essential genes identified by the method of claim 1 , wherein said library comprises at most about 530-543 genes.
14. An essential gene identified by the method of claim 8 .