Smitha Shambhu (United States of America)
University of Central Florida
Burnett School of Biomedical Sciences
I currently work with the Gene Therapy team at Gordian Biotechnology on optimizing AAV vector production and purification. I also contribute to the single cell sequencing efforts, plasmid cloning and production that makes our in vivo therapeutic screening platform work. As a graduate student in the Azarian Lab at UCF I conducted research focused on mechanisms of horizontal gene transfer in Streptococcus pneumoniae influenced by changes in gene expression.

Presenter of 1 Presentation

 Conference Calendar

O027 - DIFFERENTIAL EXPRESSION OF COMPETENCE GENES ASSOCIATED WITH VARIATION IN TRANSFORMATION FREQUENCIES AMONG SEROTYPE 3 STREPTOCOCCUS PNEUMONIAE (ID 176)

Session Name
0340 - Parallel Session 04: Genome Sequencing, Molecular Epidemiology and Emerging Technologies (ID 26)
Session Type
Parallel Session
Date
Mon, 20.06.2022
Session Time
15:20 - 16:35
Room
Birchwood Ballroom
Presenter
Lecture Time
16:25 - 16:35

Abstract

Background

Recombination has shaped the evolutionary history of Streptococcus pneumoniae, allowing rapid adaptation to interventions. Pneumococci can undergo recombination through natural competence – a state in which bacteria can uptake DNA from the environment. Recombination frequencies vary considerably across pneumococcal populations; yet the underlying mechanisms for these variations are not well understood.

Methods

We sought to elucidate differences in transformation frequency and the underlying genetic mechanisms among strains from two distinct phylogenetic clades of Serotype 3 belonging clonal complex (CC) 180 and a well-characterized non-CC180 comparison strain D39. To this end, we performed in-vitro competence assays and measured differential expression of early and late competence genes using RNA-sequencing.

Results

We found consistent differences in transformation frequencies among CC180 clades and D39 (Figure 1), which correlated with variation in differentially expressed genes during competence. While all strains exhibited a similar response to competence stimulating peptide for early competence genes, expression of late competence genes encoding the DNA uptake apparatus, DNA repair and recombination proteins needed for recombination were attenuated among strains demonstrating lower transformation frequencies. We also observed differences in expression of genes linked to bacteriocin production, which may partially explain observed population genomic-level differences. Further genomic analysis suggests variation in promoter sequences governing late competence genes may be slowing transition from early to late components of the competence pathway.

isppd_fig1.png

Conclusions

We show that there is considerable variation in competence even among closely related strains and that this variation may be the result of subtle genomic differences.

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