1
|
Imholz NCE, Noga MJ, van den Broek NJF, Bokinsky G. Calibrating the Bacterial Growth Rate Speedometer: A Re-evaluation of the Relationship Between Basal ppGpp, Growth, and RNA Synthesis in Escherichia coli. Front Microbiol 2020; 11:574872. [PMID: 33042085 PMCID: PMC7527470 DOI: 10.3389/fmicb.2020.574872] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 08/25/2020] [Indexed: 01/20/2023] Open
Abstract
The molecule guanosine tetraphophosphate (ppGpp) is most commonly considered an alarmone produced during acute stress. However, ppGpp is also present at low concentrations during steady-state growth. Whether ppGpp controls the same cellular targets at both low and high concentrations remains an open question and is vital for understanding growth rate regulation. It is widely assumed that basal ppGpp concentrations vary inversely with growth rate, and that the main function of basal ppGpp is to regulate transcription of ribosomal RNA in response to environmental conditions. Unfortunately, studies to confirm this relationship and to define regulatory targets of basal ppGpp are limited by difficulties in quantifying basal ppGpp. In this Perspective we compare reported concentrations of basal ppGpp in E. coli and quantify ppGpp within several strains using a recently developed analytical method. We find that although the inverse correlation between ppGpp and growth rate is robust across strains and analytical methods, absolute ppGpp concentrations do not absolutely determine RNA synthesis rates. In addition, we investigated the consequences of two separate RNA polymerase mutations that each individually reduce (but do not abolish) sensitivity to ppGpp and find that the relationship between ppGpp, growth rate, and RNA content of single-site mutants remains unaffected. Both literature and our new data suggest that environmental conditions may be communicated to RNA polymerase via an additional regulator. We conclude that basal ppGpp is one of potentially several agents controlling ribosome abundance and DNA replication initiation, but that evidence for additional roles in controlling macromolecular synthesis requires further study.
Collapse
Affiliation(s)
- Nicole C E Imholz
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Marek J Noga
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Niels J F van den Broek
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Gregory Bokinsky
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| |
Collapse
|
2
|
Malik S, Petrova MI, Imholz NCE, Verhoeven TLA, Noppen S, Van Damme EJM, Liekens S, Balzarini J, Schols D, Vanderleyden J, Lebeer S. High mannose-specific lectin Msl mediates key interactions of the vaginal Lactobacillus plantarum isolate CMPG5300. Sci Rep 2016; 6:37339. [PMID: 27853317 PMCID: PMC5112522 DOI: 10.1038/srep37339] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/21/2016] [Indexed: 12/12/2022] Open
Abstract
To characterize the interaction potential of the human vaginal isolate Lactobacillus plantarum CMPG5300, its genome was mined for genes encoding lectin-like proteins. cmpg5300.05_29 was identified as the gene encoding a putative mannose-binding lectin. Phenotypic analysis of a gene knock-out mutant of cmpg5300.05_29 showed that expression of this gene is important for auto-aggregation, adhesion to the vaginal epithelial cells, biofilm formation and binding to mannosylated glycans. Purification of the predicted lectin domain of Cmpg5300.05_29 and characterization of its sugar binding capacity confirmed the specificity of the lectin for high- mannose glycans. Therefore, we renamed Cmpg5300.05_29 as a mannose-specific lectin (Msl). The purified lectin domain of Msl could efficiently bind to HIV-1 glycoprotein gp120 and Candida albicans, and showed an inhibitory activity against biofilm formation of uropathogenic Escherichia coli, Staphylococcus aureus and Salmonella Typhimurium. Thus, using a combination of molecular lectin characterization and functional assays, we could show that lectin-sugar interactions play a key role in host and pathogen interactions of a prototype isolate of the vaginal Lactobacillus microbiota.
Collapse
Affiliation(s)
- Shweta Malik
- KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium.,University of Antwerp, Department of Bioscience Engineering, Research Group Environmental Ecology and Applied Microbiology, Antwerp, Belgium
| | - Mariya I Petrova
- KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium.,University of Antwerp, Department of Bioscience Engineering, Research Group Environmental Ecology and Applied Microbiology, Antwerp, Belgium
| | - Nicole C E Imholz
- KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium.,University of Antwerp, Department of Bioscience Engineering, Research Group Environmental Ecology and Applied Microbiology, Antwerp, Belgium
| | | | - Sam Noppen
- KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Els J M Van Damme
- Ghent University, Department of Molecular Biotechnology, Ghent, Belgium
| | - Sandra Liekens
- KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Jan Balzarini
- KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Dominique Schols
- KU Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Jos Vanderleyden
- KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium
| | - Sarah Lebeer
- KU Leuven, Centre of Microbial and Plant Genetics, Leuven, Belgium.,University of Antwerp, Department of Bioscience Engineering, Research Group Environmental Ecology and Applied Microbiology, Antwerp, Belgium
| |
Collapse
|
3
|
Petrova MI, Imholz NCE, Verhoeven TLA, Balzarini J, Van Damme EJM, Schols D, Vanderleyden J, Lebeer S. Lectin-Like Molecules of Lactobacillus rhamnosus GG Inhibit Pathogenic Escherichia coli and Salmonella Biofilm Formation. PLoS One 2016; 11:e0161337. [PMID: 27537843 PMCID: PMC4990349 DOI: 10.1371/journal.pone.0161337] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 08/03/2016] [Indexed: 01/01/2023] Open
Abstract
Objectives Increased antibiotic resistance has catalyzed the research on new antibacterial molecules and alternative strategies, such as the application of beneficial bacteria. Since lectin molecules have unique sugar-recognizing capacities, and pathogens are often decorated with sugars that affect their survival and infectivity, we explored whether lectins from the probiotic strain Lactobacillus rhamnosus GG have antipathogenic properties. Methods The genome sequence of L. rhamnosus GG was screened for the presence of lectin-like proteins. Two genes, LGG_RS02780 and LGG_RS02750, encoding for polypeptides with an N-terminal conserved L-type lectin domain were detected and designated Llp1 (lectin-like protein 1) and Llp2. The capacity of Llp1 and Llp2 to inhibit biofilm formation of various pathogens was investigated. Sugar specificity was determined by Sepharose beads assays and glycan array screening. Results The isolated lectin domains of Llp1 and Llp2 possess pronounced inhibitory activity against biofilm formation by various pathogens, including clinical Salmonella species and uropathogenic E. coli, with Llp2 being more active than Llp1. In addition, sugar binding assays with Llp1 and Llp2 indicate specificity for complex glycans. Both proteins are also involved in the adhesion capacity of L. rhamnosus GG to gastrointestinal and vaginal epithelial cells. Conclusions Lectins isolated from or expressed by beneficial lactobacilli could be considered promising bio-active ingredients for improved prophylaxis of urogenital and gastrointestinal infections.
Collapse
Affiliation(s)
- Mariya I. Petrova
- KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, box 2460, B-3001, Leuven, Belgium
- University of Antwerp, Department of Bioscience Engineering, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
- * E-mail: (SL); (MIP)
| | - Nicole C. E. Imholz
- KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, box 2460, B-3001, Leuven, Belgium
| | - Tine L. A. Verhoeven
- KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, box 2460, B-3001, Leuven, Belgium
| | - Jan Balzarini
- KU Leuven, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000, Leuven, Belgium
| | - Els J. M. Van Damme
- Ghent University, Laboratory of Biochemistry and Glycobiology, Department of Molecular Biotechnology, Coupure Links 653, B-9000, Ghent, Belgium
| | - Dominique Schols
- KU Leuven, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000, Leuven, Belgium
| | - Jos Vanderleyden
- KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, box 2460, B-3001, Leuven, Belgium
| | - Sarah Lebeer
- KU Leuven, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20, box 2460, B-3001, Leuven, Belgium
- University of Antwerp, Department of Bioscience Engineering, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
- * E-mail: (SL); (MIP)
| |
Collapse
|