Journal of Microbiology

Journal Article

The Salmonella enterica EnvE is an Outer Membrane Lipoprotein and Its Gene Expression Leads to Transcriptional Repression of the Virulence Gene msgA: Sinyeon Kim, Yong Heon Lee; J. Microbiol. 2024;62(11):1013-1022. Published online November 15, 2024; DOI: https://doi.org/10.1007/s12275-024-00183-4

306 View
12 Download

Abstract PDF: The envE gene of Salmonella enterica serovar Typhimurium is encoded within Salmonella Pathogenicity Island-11 (SPI-11) and is located immediately upstream of the virulence gene msgA (macrophage survival gene A) in the same transcriptional orientation. To date, the characteristics and roles of envE remain largely unexplored. In this study, we show that EnvE, a predicted lipoprotein, is localized on the outer membrane using sucrose gradient ultracentrifugation. Under oxidative stress conditions, envE transcription is suppressed, while msgA transcription is induced, indicating an inverse correlation between the mRNA levels of the two neighboring genes. Importantly, inactivation of envE leads to constitutive transcription of msgA regardless of the presence of oxidative stress. Moreover, trans-complementation of the envE mutant with a plasmid-borne envE fails to prevent the induction of msgA transcription, suggesting that envE functions as a cis-regulatory element rather than a trans-acting factor. We further show that both inactivation and complementation of envE confer wild-type levels of resistance to oxidative stress by ensuring the expression of msgA. Our data suggest that the S. enterica envE gene encodes an outer membrane lipoprotein, and its transcription represses msgA expression in a cis-acting manner, probably by transcriptional interference, although the exact molecular details are yet unclear.

Review

Extensive Genomic Rearrangement of Catalase-Less Cyanobloom-Forming Microcystis aeruginosa in Freshwater Ecosystems: Minkyung Kim, Jaejoon Jung, Wonjae Kim, Yerim Park, Che Ok Jeon, Woojun Park; J. Microbiol. 2024;62(11):933-950. Published online October 8, 2024; DOI: https://doi.org/10.1007/s12275-024-00172-7

430 View
9 Download
3 Web of Science
3 Crossref

Many of the world's freshwater ecosystems suffer from cyanobacteria-mediated blooms and their toxins. However, a mechanistic understanding of why and how Microcystis aeruginosa dominates over other freshwater cyanobacteria during warmer summers is lacking. This paper utilizes comparative genomics with other cyanobacteria and literature reviews to predict the gene functions and genomic architectures of M. aeruginosa based on complete genomes. The primary aim is to understand this species' survival and competitive strategies in warmer freshwater environments. M. aeruginosa strains exhibiting a high proportion of insertion sequences (~ 11%) possess genomic structures with low synteny across different strains. This indicates the occurrence of extensive genomic rearrangements and the presence of many possible diverse genotypes that result in greater population heterogeneities than those in other cyanobacteria in order to increase survivability during rapidly changing and threatening environmental challenges. Catalase-less M. aeruginosa strains are even vulnerable to low light intensity in freshwater environments with strong ultraviolet radiation. However, they can continuously grow with the help of various defense genes (e.g., egtBD, cruA, and mysABCD) and associated bacteria. The strong defense strategies against biological threats (e.g., antagonistic bacteria, protozoa, and cyanophages) are attributed to dense exopolysaccharide (EPS)-mediated aggregate formation with efficient buoyancy and the secondary metabolites of M. aeruginosa cells. Our review with extensive genome analysis suggests that the ecological vulnerability of M. aeruginosa cells can be overcome by diverse genotypes, secondary defense metabolites, reinforced EPS, and associated bacteria.

Citations

Citations to this article as recorded by

Cyanophage Infections in a Sponge Intracellular Cyanobacterial Symbiont
Tzipora Peretz, Esther Cattan‐Tsaushu, Chiara Conti, Benyamin Rosental, Laura Steindler, Sarit Avrani
Environmental Microbiology.2025;[Epub] CrossRef
Public goods-mediated bacterial interplay in aquatic ecosystems
Yerim Park, Wonjae Kim, Jihye Bae, Woojun Park
Water Research.2025; 287: 124310. CrossRef
Horizontal Gene Transfer and Recombination in Cyanobacteriota
Devaki Bhaya, Gabriel Birzu, Eduardo P.C. Rocha
Annual Review of Microbiology .2025; 79(1): 685. CrossRef

Journal Articles

Comparative Transcriptomic Analysis of Flagellar‑Associated Genes in Salmonella Typhimurium and Its rnc Mutant: Seungmok Han , Ji-Won Byun , Minho Lee; J. Microbiol. 2024;62(1):33-48. Published online January 5, 2024; DOI: https://doi.org/10.1007/s12275-023-00099-5

483 View
14 Download
3 Web of Science
3 Crossref

Search