Journal of Microbiology

Journal Article

Availability of polyamines affects virulence and survival of Neisseria meningitidis: Poonam Kanojiya , Riya Joshi , Sunil D. Saroj; J. Microbiol. 2022;60(6):640-648. Published online April 18, 2022; DOI: https://doi.org/10.1007/s12275-022-1589-y

Abstract: Neisseria meningitidis is a Gram-negative human-restricted pathogen that asymptomatically resides in the human respiratory tract. Meningococcal meningitis and sepsis both are caused by N. meningitidis. The bacterium must adhere to host epithelial cells in order to colonize effectively. The factors that determine the initial attachment to the host and dispersal, are not well understood. Metabolites released by the host may aid in meningococcal colonization and dissemination. Polyamines are aliphatic polycations that assist in cell survival and proliferation. The virulence properties of N. meningitidis after exposure to polyamines were investigated. Adhesion to nasopharyngeal epithelial cells increased in the presence of spermine. Also, the relative expression of adhesin, pilE increased in the presence of spermine. Further, relative expression of ctrA, ctrB and lipB was upregulated in the presence of spermidine, indicating increased capsule formation. Upregulated capsule synthesis of N. meningitidis in the presence of spermidine allows it to survive in murine macrophages. The study suggests the importance of the extracellular pool of polyamines in promoting virulence in N. meningitidis.

Analysis of the Dual Promoters and the H 2 O 2 -responsive Element of the catA Gene Encoding Catalase A in Streptomyces coelicolor: You-Hee Cho , Ji-Sook Hahn , Jung-Hye Roe; J. Microbiol. 2000;38(4):239-244.

Abstract: The catA gene encodes the major catalase in Streptomyces coelicolor, whose production increases upon H_2O_2 treatment. Besides the previously identified primary promoter (catAp1), a minor promoter (catAp2) was newly assigned by S1 nuclease mapping. The catAp2 transcript was observed transiently upon entry into the stationary phase in liquid culture and upon differentiation on solid plates, whereas the level of catAp1 transcription did not change significantly during this growth transition. The catAp1 promoter was transcribed by the major vegetative RNA polymerase holoenzyme containing [sigma]^HrdB , whereas the catAp2 was transcribed in vitro by the holoenzyme containing [sigma]^R that is activated under oxidative conditions. The cis-element regulating the H_2 O_2 -inducibility of catAp1 was identified within the 23 bp inverted repeat sequence located between -65 and -43 of the catAp1 promoter. We named this sequence HRE (H_2O_2 -responsive element). The distal half of the inverted repeat was more crucial for H_2 O_2 ?pendent induction of the catAp1 transcript than the proximal half. HRE most likely serves as a binding site for the H_2 O_2 -responsive repressor CatR.

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