Transcript Role of nucleotide polymorphisms in evolution of Staphylococcal

Role of Nucleotide
Polymorphisms in Evolution of
Staphylococcal Minimal Genome
Karthi Sivaraman
Department of Molecular and Microbiology,
University of Central Florida
The common minimal genome
of Staphylococcus aureus
• Common minimal genome (CMG)
– Set of orthologous genes present in all the strains
of a given species
• The staphylococcal CMG (14 strains)
• 2001 genes
–765 genes of known function
–1236 Hypothetical proteins
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Non-Synonymous SNP distribution
in the S. aureus CMG
Log (No. of Genes)
3.5
3
2.5
2
1.5
1
0.5
0
>1
0
10
9-
9
8-
8
7-
7
6-
6
5-
5
4-
4
3-
3
2-
2
1-
1
0-
0
% (SNP normalized to gene length)
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Classification of Genes with high
SNP variation – Top 5%
0%
13%
2%
9%
54%
macromolecular
synthesis
regulation
metabolism
cellular functions
energy
2%
20%
pathogenesis /
biofilms
others
Majority of the genes belong to pathogenicity (20) / biofilm (4)
formation group
Total genes in category = 199
Total genes for which function could be assigned = 45
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Classification of Genes with zero
non-synonymous SNP
15%
2%3% 2%
macromolecular
synthesis
regulation
26%
metabolism
cellular functions
43%
energy
pathogenicity
9%
others
Majority of the genes belong to metabolism and
macromolecule biosynthesis groups
Total genes in category = 637
Total genes for which function could be assigned = 268
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Conclusions
• Pathogenesis related genes in S. aureus
minimal genome accrue more SNPs than do
house keeper genes
• Evolution of S. aureus pathogenicity involves
both large scale horizontal gene transfer as well
as micro scale changes in the minimal genome.
Acknowledgements
Dr. Alexander Cole, Nitya Venkataraman,
and Conference Organizers
Funding
NIH Grant 5R01-AI060753 to Alexander M Cole
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