Ejemplo de Poster

1. Y-B9 Characterization of a plasmid pMBA19a in a strain of
Sinorhizobium meliloti. Role of this plasmid in the quorum sensing associated
Characterization of a plasmid pMBA19a in a strain of Sinorhizobium meliloti. Role of this plasmid in the quorum sensing associated
phenotypes
phenotypes
Monica Cartelle Gestal, Stephan Heeb and Miguel Camara.
Monica Cartelle Gestal, Stephan Heeb and Miguel Camara.
Centre for Biomolecular Sciences. University of Nottingham. monica.gestal@nottingham.ac.uk. SINOPLASMID (RH0735)
Centre for Biomolecular Sciences. University of Nottingham. monica.gestal@nottingham.ac.uk. SINOPLASMID (RH0735)
INTRODUCTION
The research project is focused on a cryptic plasmid from Sinorhizobium meliloti, a root-colonizing bacterium used for centuries to improve the fertility of agricultural soils. This bacterium interacts with the roots of plants and induces the formation of nitrogenfixing nodules, allowing them to utilise atmospheric nitrogen for their growth and in the long term improving the fertility of the soil and hence increasing crop production, S. meliloti can also act as biocontrol agents against fungal and viral infections.
Partial sequence of the cryptic plasmid pMBA19a isolated from S. meliloti strain MBA19, was already published in 2006. This sequence revealed for the first time the presence of a gene encoding an RsmA homolog carried by a plasmid. RsmA homologues are
small-RNA binding proteins that have profound implications in the physiology of bacteria by acting as a global post-transcriptional regulators of gene expression. As cryptic plasmids have the propensity to disseminate between useful and deleterious bacteria in
the environment, a better understanding of implications of them coding important gene expression regulators like RsmA is paramount. Using pMBA19a as a model plasmid in S. meliloti and Pseudomonas aeruginosa, we undertake to evaluate its impact on the
biology of bacterial species of clinical and agronomic importance.
Pseudomonas aeruginosa
RESULTS
RsmA
RsmA
Restriction
Restriction
endonuclease
endonuclease
Enzymes
Metabolism
Replication genes
TCS
TCS
Conjugation genes
Plasmid highly transferable
Maintenance
G
E
N
E
S
RsmA = Posttranscriptional
regulator
Restriction
Restriction
endonuclease
endonuclease
Two component
Two component
systems (TCS) =
systems (TCS) =
Regulatory system
Regulatory system
Other unknown
Other unknown
genes or regulators
genes or regulators
P
H
E
N
O
T
Y
P
E
Sinorhizobium meliloti
Control (no plasmid)
AHLs
pBB84 =
pBBR328+4.5 kb rep
(vector + 4.5 Kb of the
plasmid pMBA19a)
pMBA19a (all the
plasmid pMBA19a)
AHL (n-Acyl Homoserine Lactones). Molecules that a
variety of gram negative bacteria, use for signalling and
communication affecting the behaviour of the cell
population
These photos show the motility of P. aeruginosa in swarming agar. This
phenomena is known as swarming, that is a rapid and coordinate movement of
the bacterial population across solid or semi-solid surface.
Sinorhizobium meliloti
With thw plasmid pMBA19a
Without the plasmid pMBA19a
Morphology
These photos show the morphology of the colony of S. meliloti under the microscope and
how this is clearly affected for the presence of this plasmid
CONCLUSION
The preliminary results show that this plasmid affects several phenotypes and functions in different hosts
including Sinorhizobium meliloti (which has implications in agriculture) or Pseudomonas aeruginosa
(which is an important pathogen)
This is the first time that some of the genes that are present on this plasmid, have been found in a mobile
element.
Cryptic plasmids and some of these regulatory systems are present in many organisms of importance to
medicine, industry and agriculture. The results obtained from this multidisciplinary IEF project will set up a
platform for the optimisation of inoculants in agriculture. This will also enable the discovery of novel
relationships between regulatory networks which by extent will have an impact on the identification of
novel conserved antibacterial targets against a wide range of bacterial pathogens which harbour cryptic
plasmids.
IMPACT
Research
Research