Biology subjects

Synefiaridou, D.

Publications and source records attributed to Synefiaridou, D..

3 recordsLinked to original sources

bioRxiv2026

Genome-wide interrogation of genetic requirements for root colonization by CRISPRi-seq in Bacillus subtilis

Bacillus subtilis is a known plant growth promoting rhizobacterium, yet, the genetic basis of effective root colonization remains understudied. Here, we applied genome-wide CRISPR interference sequencing (CRISPRi-seq) to systematically identify genes required for early Arabidopsis thaliana root colonization by the B. subtilis strain 3610 . Our genome-wide inducible CRISPRi library was used to screen for bacterial fitness during hydroponic root colonization. A complementary RNA-seq in the same conditions further revealed a distinct transcriptional state of root-associated cells. We identified 249 genes impacting root colonization. We reveal a critical role of cell envelope remodeling during early root association, specifically wall teichoic acid synthesis and D-alanylation. Moreover, we observed a metabolic shift toward TCA-cycle-driven aerobic growth with uptake of fructose, active repression of sporulation, competence and prophage programs, as well as induction of secondary metabolite biosynthesis. Our work establishes CRISPRi-seq as a powerful tool for dissecting bacterial-plant interactions relevant to sustainable agriculture.

microbiology↗

bioRxiv2022

Competence remodels the pneumococcal cell wall providing resistance to fratricide and surface exposing key virulence factors

Competence development in the human pathogen Streptococcus pneumoniae controls several features such as genetic transformation, biofilm formation and virulence. Competent bacteria produce so called fratricins such as CbpD, that kill non-competent siblings by cleaving peptidoglycan (PGN). CbpD is a choline-binding protein (CBP) that binds to phosphorylcholine residues found on wall- and lipoteichoic acids (WTA and LTA) that together with PGN are major constituents of the pneumococcal cell wall. Competent pneumococci are protected against fratricide by producing the immunity protein ComM. How competence and fratricide contribute to virulence is unknown. Here, using a genome-wide CRISPRi-seq screen, we show that genes involved in teichoic acid biosynthesis are essential during competence. We demonstrate that LytR is the major enzyme mediating the final step in WTA formation, and that, together with ComM, is essential for immunity against CbpD. Importantly, we show that key virulence factors PspA and PspC become more surface-exposed at midcell during competence, in a CbpD-dependent manner. Together, our work supports a model in which activation of competence is crucial for host adherence by increased surface exposure of its various CBPs.

microbiology↗

bioRxiv2020

Harnessing CRISPR-Cas9 for genome editing in Streptococcus pneumoniae

CRISPR systems provide bacteria and archaea with adaptive immunity against viruses and plasmids by detection and cleavage of invading foreign DNA. Modified versions of this system can be exploited as a biotechnological tool for precise genome editing at a targeted locus. Here, we developed a novel, replicative plasmid that carries the CRISPR-Cas9 system for RNA-programmable, genome editing by counterselection in the opportunistic human pathogen Streptococcus pneumoniae. Specifically, we demonstrate an approach for making targeted, marker-less gene knockouts and large genome deletions. After a precise double-stranded break (DSB) is introduced, the cells DNA repair mechanism of homology-directed repair (HDR) pathway is being exploited to select successful transformants. This is achieved through the transformation of a template DNA fragment that will recombine in the genome and eliminate recognition of the target of the Cas9 endonuclease. Next, the newly engineered strain, can be easily cured from the plasmid that is temperature-sensitive for replication, by growing it at the non-permissive temperature. This allows for consecutive rounds of genome editing. Using this system, we engineered a strain with three major virulence factors deleted. The here developed approaches should be readily transportable to other Gram-positive bacteria. ImportanceStreptococcus pneumoniae (the pneumococcus) is an important opportunistic human pathogen killing over a million people each year. Having the availability of a system capable of easy genome editing would significantly facilitate drug discovery and vaccine candidate efforts. Here, we introduced an easy to use system to perform multiple rounds of genome editing in the pneumococcus by putting the CRISPR-Cas9 system on a temperature-sensitive replicative plasmid. The here used approaches will advance genome editing projects in this important human pathogen.

microbiology↗