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ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.
Sec. Molecular Bacterial Pathogenesis
Volume 14 - 2024 | doi: 10.3389/fcimb.2024.1499476

Multiple Factors Regulate the Expression of sufCDSUB in Streptococcus mutans

Provisionally accepted
Kassapa Ellepola Kassapa Ellepola 1Lauren C. Guillot Lauren C. Guillot 1Bradley J. Comeaux Bradley J. Comeaux 1Yiran (. Han Yiran (. Han 2Jessica Kajfasz Jessica Kajfasz 3Jacob P. Bitoun Jacob P. Bitoun 4Grace A. Spatafora Grace A. Spatafora 2Jose Lemos Jose Lemos 5Zezhang T. Wen Zezhang T. Wen 1*
  • 1 LSU Health Sciences Center New Orleans, Louisiana State University, New Orleans, United States
  • 2 Department of Biology, Middlebury College, Middlebury, VT, Vermont, United States
  • 3 College of Dentistry, University of Florida, Gainesville, Florida, United States
  • 4 Department of Microbiology and Immunology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
  • 5 Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida, United States

The final, formatted version of the article will be published soon.

    The sufCDSUB gene cluster, encoding the sole iron-sulfur (Fe-S) cluster assembly system in S. 29 mutans, was recently shown to be up-regulated in response to oxidative stressors and Fe 30 limitation. In this study, luciferase reporter fusion assays, electrophoretic gel mobility shift 31 assays (EMSA) and in vitro transcription assays (IVT) were used to dissect the cis-and trans-32 acting factors that regulate the expression of sufCDSUB. Results showed deletion of perR, for the 33 only Fur-family transcriptional regulator in S. mutans, resulted in >5-fold increases in luciferase 34 activity under the control of the sufCDSUB promoter (P<0.01), as compared to the parent strain, 35 UA159 when the reporter strains were grown in medium with no supplemental iron. Site-directed 36 mutagenesis of a PerR-box in the promoter region led to elevation of the reporter activity by 37 >1.6-fold (P<0.01). In an EMSA, recombinant PerR (rPerR) was shown to bind to the cognate 38 sufCDSUB promoter leading to mobility retardation. On the other hand, the reporter activity was 39 increased by >84-fold (P<0.001) in response to the addition of cysteine at 4 mM to the culture 40 medium. Deletion of cysR, for a LysR-type of transcriptional regulator, led to reduction of the 41 reporter activity by >11.6-fold (P<0.001). Addition of recombinant CysR (rCysR) to an EMSA 42 caused mobility shift of the sufCDSUB promoter probe, indicative of rCysR-promoter 43 interaction, and rCysR was shown to enhance sufC transcription under the direction of 44 sufCDSUB promoter in vitro. These results suggest that multiple factors are involved in the 45 regulation of sufCDSUB expression in response to environmental cues, including cysteine and Fe 46 availability, consistent with the important role of sufCDSUB in S. mutans physiology.

    Keywords: Streptococcus mutans, sufCDSUB, regulation of Fe-S cluster genes, PerR, CysR, SLOR, SpxA2, DPR

    Received: 20 Sep 2024; Accepted: 05 Nov 2024.

    Copyright: © 2024 Ellepola, Guillot, Comeaux, Han, Kajfasz, Bitoun, Spatafora, Lemos and Wen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Zezhang T. Wen, LSU Health Sciences Center New Orleans, Louisiana State University, New Orleans, United States

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