Biology subjects

Anandan, V.

Publications and source records attributed to Anandan, V..

3 recordsLinked to original sources

bioRxiv2026

A genome-wide in vivo screen reveals fitness pathways required for streptococcal infective endocarditis

Infective endocarditis (IE) is a life-threatening disease most often caused by blood-borne bacteria that infect previously damaged cardiac tissue. Despite the importance of this disease, the genetic basis for IE virulence remains poorly defined. Here, we present the first genome-wide in vivo analysis of bacterial fitness in a vertebrate model of IE. We identified 146 genes in Streptococcus sanguinis required for IE fitness, the majority of which had not previously been linked to endocarditis. These determinants cluster into conserved metabolic, cell envelope, transport, and regulatory pathways, representing a vast reservoir of potential targets for novel antimicrobial intervention. A subset of these genes was examined in Streptococcus mutans; all were found to be essential for IE fitness in this distantly related oral species as well, suggesting broad conservation. Using experimental evolution, we further show that disruption of key fitness pathways triggers reproducible compensatory "bypass" mechanisms that reveal the inherent physiological constraints of the IE fitness landscape and identify vulnerable nodes for multi-target drug strategies. Together, these findings redefine streptococcal infective endocarditis as a disease shaped by conserved bacterial fitness networks that may be exploited for therapeutic development. HighlightsO_LIA genome-wide in vivo screen identified 146 Streptococcus sanguinis genes required for infective endocarditis fitness. C_LIO_LI94% of these genes represent previously unrecognized determinants of endocarditis. C_LIO_LIMultiple pathways--including CoA biosynthesis, the shikimate pathway, and rhamnan synthesis--are required for cardiac colonization. C_LIO_LIA subset of infective endocarditis fitness factors are conserved between S. sanguinis and S. mutans, with species-specific adaptations. C_LIO_LIExperimental evolution revealed compensatory metabolic networks that buffer IE fitness defects. C_LI

genetics↗

bioRxiv2024

Experimental evolution of gene essentiality in bacteria

Essential gene products carry out fundamental cellular activities in interaction with other components. However, the lack of essential gene mutants and appropriate methodologies to link essential gene functions with their partners poses significant challenges. Here, we have generated deletion mutants in 32 genes previously identified as essential, with 23 mutants showing extremely slow growth in the SK36 strain of Streptococcus sanguinis. The 23 genes corresponding to these mutants encode components of diverse pathways, are widely conserved among bacteria, and are essential in many other bacterial species. Whole-genome sequencing of 243 independently evolved populations of these mutants has identified >1000 spontaneous suppressor mutations in experimental evolution. Many of these mutations define new gene and pathway relationships, such as F1Fo-ATPase/V1Vo-ATPase/TrkA1-H1 that were demonstrated across multiple Streptococcus species. Patterns of spontaneous mutations occurring in essential gene mutants differed from those found in wildtype. While gene duplications occurred rarely and appeared most often at later stages of evolution, substitutions, deletions, and insertions were prevalent in evolved populations. These essential gene deletion mutants and spontaneous mutations fixed in the mutant populations during evolution establish a foundation for understanding gene essentiality and the interaction of essential genes in networks.

evolutionary biology↗

bioRxiv2024

A novel infective endocarditis virulence factor related to multiple functions for bacterial survival in blood was discovered in Streptococcus sanguinis

We identified the role of a conserved hypothetical protein (SSA_0451) in S. sanguinis that is involved in the virulence of infective endocarditis. An in vitro whole blood killing assay and rabbit endocarditis model studies revealed that the SSA_0451 mutant ({Delta}SSA_0451) was significantly less virulent than the wild-type (SK36) and its complementation mutant ({Delta}SSA_0451C). The mechanism underlying the SSA_0451 mutants reduced virulence in infective endocarditis was evidentially linked to oxidative stress and environmental stress. The genes related to the survival of S. sanguinis in an oxidative stress environment were downregulated in {Delta}SSA_0451, which affected its survival in blood. Our findings suggest that SSA_0451 is a novel IE virulence factor and a new target for drug discovery against IE. Author summaryThis study focused on SSA_0451, a conserved hypothetical protein in S. sanguinis, to explore its potential role as a virulence factor. Through in vitro whole blood killing assays and rabbit IE models, it was found that the SSA_0451 mutant exhibited reduced virulence compared to the wild-type and a complemented mutant. The study linked the mutants diminished virulence in IE to heightened susceptibility to oxidative and environmental stresses, supported by downregulation of genes crucial for oxidative stress survival in S. sanguinis. These findings identify SSA_0451 as a novel virulence factor in IE and propose it as a promising target for future drug development against this condition.

microbiology↗