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Roles of Alternative Sigma Factors in Invasion and Growth Characteristics of Listeria monocytogenes 10403S Into Human Epithelial Colorectal Adenocarcinoma Caco-2 Cell
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Document Title
Roles of Alternative Sigma Factors in Invasion and Growth Characteristics of Listeria monocytogenes 10403S Into Human Epithelial Colorectal Adenocarcinoma Caco-2 Cell
Author
Rukit J, Boonmee A, Kijpornyongpan T, Tulsook K, Baranyi J, Chaturongakul S
Name from Authors Collection
Affiliations
Mahidol University; Chulalongkorn University; Purdue University System; Purdue University; Purdue University West Lafayette Campus; National Science & Technology Development Agency - Thailand; National Center Genetic Engineering & Biotechnology (BIOTEC); University of Debrecen; Mahidol University
Type
Article
Source Title
FRONTIERS IN MICROBIOLOGY
Year
2022
Volume
13
Open Access
gold, Green Published
Publisher
FRONTIERS MEDIA SA
DOI
10.3389/fmicb.2022.901484
Format
Abstract
Listeria monocytogenes is a Gram-positive facultative intracellular bacterium with a broad host range. With its housekeeping sigma factor and four alternative ones (namely SigB, SigC, SigH, and SigL), L. monocytogenes can express genes in response to changing environments. However, the roles of these sigma factors in intracellular survival are still unclear. The objectives of this study were to characterize the role of each alternative sigma factor on L. monocytogenes invasion and growth inside human epithelial colorectal adenocarcinoma Caco-2 cells. We used L. monocytogenes 10403S wild type and its 15 alternative sigma factor deletion mutants at a multiplicity of infection of 100 and 1 in invasion and intracellular growth assays in the Caco-2 cells, respectively. At 1.5, 2, 4, 6, 8, 10, and 12 h post-infection, Caco-2 cells were lysed, and intracellular L. monocytogenes were enumerated on brain-heart infusion agar. Colony-forming and growth rates were compared among strains. The results from phenotypic characterization confirmed that (i) SigB is the key factor for L. monocytogenes invasion and (ii) having only SigA (Delta sigBCHL strain) is sufficient to invade and multiply in the host cell at similar levels as the wild type. Our previous study suggested the negative role of SigL in bile stress response. In this study, we have shown that additional deletion of the rpoN (or sigL) gene to Delta sigB, Delta sigC, or Delta sigH could restore the impaired invasion efficiencies of the single mutant, suggesting the absence of SigL could enhance host invasion. Therefore, we further investigated the role of SigL during extracellular and intracellular life cycles. Using RNA sequencing, we identified 118 and 16 SigL-dependent genes during the extracellular and intracellular life cycles, respectively. The sigL gene itself was induced by fivefolds prior to the invasion, and 5.3 folds during Caco-2 infection, further suggesting the role of SigL in intracellular growth.
Keyword
Caco-2 cell | invasion | Listeria monocytogenes | RNA sequencing | Transcriptomics
License
CC BY
Rights
Authors
Publication Source
WOS