1. Are multiple Streptomyces
dpsB genes the result of a gene
duplication event ?
Hemlata Bisnauthsing
Supervisor: Dr. Ricardo Del Sol
Group: Molecular Microbiology

2. Background
• Dps (DNA Protection during Starvation)
 Encoded by Bacteria and Archea
Protect DNA from Oxidative stress
• Studies in Streptomyces coelicolor described three Dps-like proteins: DpsA, B and C.
dpsB seems to be the ancestral gene in Streptomyces
dpsA is stress-inducible and controlled by a sigB promoter
dpsC is unusual in sequence and probably laterally acquired from an extremophile
organism
Facey et al., Mol. Microbiol. (2009)

3. Multiple dpsB genes is a common trait in Streptomyces genomes
dpsB-like
Facey et al. PLoS One. 2013;8(4):e60772. doi: 10.1371/journal.pone.0060772.

4. Streptomyces DpsB-like
sequences distribute into
well defined sub-clades
(~200 sequences)
Neighbour Joining Tree, 500 replicates. MEGA 5

5. Strong synteny between dpsB paralog loci provides evidence for an
ancestral duplication event
COGE: https://genomevolution.org/CoGe/SynMap.pl

6. Only sequences in clade 1B possess a sigB-like
promoter, while paralogs in clades 1A ,1C and clade 3
do not
Representative dpsB-like from clade 1B that possess a putative sigB-like
promoter (predicted using Compass)

7. Is this how it happened?
Streptomyces last common ancestor
(1 dpsB-like)
Gene duplication
event
S. avermitilis
S. scabies
S. griseus
sigBp
Lateral gene transfer events
dpsB
dpsB1 dpsB2
dpsB
dpsX dpsC
dpsB
dpsA
S. coelicolor
S. albus
S. iranensis Gene loss
S. venezuelaedpsC
Hypothetical
Clade 3 organisms?

8. Summary
• The last common ancestor to Streptomyces underwent a gene
duplication event that led to multiple dpsB loci.
• One dpsB paralog always possess a sigB promoter, suggesting a role
in stress response.
• A small number of dpsB orthologs (clade 3) have been laterally
acquired from Mycobacteria.