Horizontal transfer and pathogenicity Victoria Moiseeva Genomics, - - PowerPoint PPT Presentation
Horizontal transfer and pathogenicity Victoria Moiseeva Genomics, Master on Advanced Genetics UAB, Barcelona, 2014 INDEX Horizontal Transfer Horizontal gene transfer mechanisms Detection methods of HGT Examples Staphylococcus
Victoria Moiseeva Genomics, Master on Advanced Genetics UAB, Barcelona, 2014
Staphylococcus aureus Escherichia coli
Horizontal gene transfer is a process in which exogenic DNA is introduced and integrated into a recipient genome. The most transferred: transposable elements functional genes regulatory sequences All three domains: Archaea, Bacteria, and Eukarya
Several novel multi-resistant and/or hyper-virulent ‘‘superbugs’’ emerged over the last years as a result of horizontal acquisition of antibiotic resistance and virulence genes, causing serious outbreaks.
(i) difference between gene trees derived from a limited number of gene families and the reference trees such as the small-subunit ribosomal RNA (SSU rRNA) tree or whole genome tree; (ii) unexpectedly high sequence similarity of a gene from two distant genomes compared with those among homologous genes in closely related genomes; (iii) unusual nucleotide composition or codon usages of a gene compared with the rest of the genes within a genome.
Analyze of 116 prokaryotic complete genomes shows 46,759 (∼14%) of the total 324,653 ORFs were derived from recent horizontal transfers (Table 1). The average proportion of HT genes per genome was ∼12% of all ORFs, ranging from 0.5% to 25% depending on prokaryotic lineage.
Nakamura et al. Nature Genetics 36, 760 - 766 (2004)
transposon functions (28.3%)
Nakamura et al. Nature Genetics 36, 760 - 766 (2004)
Pathogenicity islands: a subset of genomic islands characterized by their capacity to encode virulence functions.
altering host cell metabolism
(e. g. acquisition of phosphate and iron at low concentrations)
Nakamura et al. Nature Genetics 36, 760 - 766 (2004)
Nakamura et al. Nature Genetics 36, 760 - 766 (2004)
While the introduction of pathogenicity islands by horizontal gene transfer is considered a hallmark in the evolution
represents only one step in a multi- faceted and complex evolutionary process.
Has the potential to cause from benign skin infections to severe diseases, such as septicaemia, osteomyelitis and endocarditis. Genomic island responsible for the spread of methicillin resistance encoding gene mecA among S. aureus is termed the staphylococcal cassette chromosome mec (SCCmec) It has been hypothesized that SCCmec island originated in Staphylococcus epidermidis and was acquired in the process of evolution of S. aureus by horizontal gene transfer
Juhas, 2013 Informa Healthcare USA 1549-7828
Kriegeskorte et al. Nature Medicine 18, 662–663 (2012)
those of non-pathogenic strains due to horizontal acquisition
strain was the result of the combination of two horizontally acquired factors: increased Shiga toxin absorption and increased antibiotic resistance Juhas, 2013 Informa Healthcare USA 1549-7828
Besides showing importance of novel technologies, the outbreaks also demonstrated the serious consequences of interspecies and intergenera horizontal transfer of virulence genes.
Hong Shen, Zhong-Huai Xiang and Ze Zhang. BMC Evolutionary Biology 2011, 11:356
104(11): 4489–4494.
Hideo Matsuda & Takashi Gojobori. Nature 2004
Karger, 2005
genome sequences” Waleed Nasser, Stephen B. Beresa, Randall J. Olsen, Melissa A. Dean, Kelsey A. et al. 2014