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Zappa S, Berne C, Morton Iii RI, Whitfield GB, De Stercke J, Brun YV. The HmrABCX pathway regulates the transition between motile and sessile lifestyles in Caulobacter crescentus by a mechanism independent of hfiA transcription. mBio 2024:e0100224. [PMID: 39230277 DOI: 10.1128/mbio.01002-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 06/03/2024] [Indexed: 09/05/2024] Open
Abstract
During its cell cycle, the bacterium Caulobacter crescentus switches from a motile, free-living state, to a sessile surface-attached cell. During this coordinated process, cells undergo irreversible morphological changes, such as shedding of their polar flagellum and synthesis of an adhesive holdfast at the same pole. In this work, we used genetic screens to identify genes involved in the regulation of the transition from the motile to the sessile lifestyle. We identified a predicted hybrid histidine kinase that inhibits biofilm formation and promotes the motile lifestyle: HmrA (holdfast and motility regulator A). Genetic screens and genomic localization led to the identification of additional genes that form a putative phosphorelay pathway with HmrA. We postulate that the Hmr pathway acts as a rheostat to control the proportion of cells harboring a flagellum or a holdfast in the population. Further genetic analysis suggests that the Hmr pathway impacts c-di-GMP synthesis through the diguanylate cyclase DgcB pathway. Our results also indicate that the Hmr pathway is involved in the regulation of motile to sessile lifestyle transition as a function of various environmental factors: biofilm formation is repressed when excess copper is present and derepressed under non-optimal temperatures. Finally, we provide evidence that the Hmr pathway regulates motility and adhesion without modulating the transcription of the holdfast synthesis regulator HfiA. IMPORTANCE Complex communities attached to a surface, or biofilms, represent the major lifestyle of bacteria in the environment. Such a sessile state enables the inhabitants to be more resistant to adverse environmental conditions. Thus, having a deeper understanding of the underlying mechanisms that regulate the transition between the motile and the sessile states could help design strategies to improve biofilms when they are beneficial or impede them when they are detrimental. For Caulobacter crescentus motile cells, the transition to the sessile lifestyle is irreversible, and this decision is regulated at several levels. In this work, we describe a putative phosphorelay that promotes the motile lifestyle and inhibits biofilm formation, providing new insights into the control of adhesin production that leads to the formation of biofilms.
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Affiliation(s)
- Sébastien Zappa
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Cécile Berne
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | | | - Gregory B Whitfield
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Jonathan De Stercke
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Yves V Brun
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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Jiménez-Venegas J, Zamora-Leiva L, Univaso L, Soto J, Tapia Y, Paneque M. Profile of Bacterial Communities in Copper Mine Tailings Revealed through High-Throughput Sequencing. Microorganisms 2024; 12:1820. [PMID: 39338494 PMCID: PMC11433839 DOI: 10.3390/microorganisms12091820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2024] [Revised: 08/27/2024] [Accepted: 08/28/2024] [Indexed: 09/30/2024] Open
Abstract
Mine-tailing dumps are one of the leading sources of environmental degradation, often with public health and ecological consequences. Due to the complex ecosystems generated, they are ideal sites for exploring the bacterial diversity of specially adapted microorganisms. We investigated the concentrations of trace metals in solid copper (Cu) mine tailings from the Ovejería Tailings Dam of the National Copper Corporation of Chile and used high-throughput sequencing techniques to determine the microbial community diversity of the tailings using 16S rRNA gene-based amplicon sequence analysis. The concentrations of the detected metals were highest in the following order: iron (Fe) > Cu > manganese (Mn) > molybdenum (Mo) > lead (Pb) > chromium (Cr) > cadmium (Cd). Furthermore, 16S rRNA gene-based sequence analysis identified 12 phyla, 18 classes, 43 orders, 82 families, and 154 genera at the three sampling points. The phylum Proteobacteria was the most dominant, followed by Chlamydiota, Bacteroidetes, Actinobacteria, and Firmicutes. Genera, such as Bradyrhizobium, Aquabacterium, Paracoccus, Caulobacter, Azospira, and Neochlamydia, showed high relative abundance. These genera are known to possess adaptation mechanisms in high concentrations of metals, such as Cd, Cu, and Pb, along with nitrogen-fixation capacity. In addition to their tolerance to various metals, some of these genera may represent pathogens of amoeba or humans, which contributes to the complexity and resilience of bacterial communities in the studied Cu mining tailings. This study highlights the unique microbial diversity in the Ovejería Tailings Dam, including the discovery of the genus Neochlamydia, reported for the first time for heavy metal resistance. This underscores the importance of characterizing mining sites, particularly in Chile, to uncover novel bacterial mechanisms for potential biotechnological applications.
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Affiliation(s)
- Joseline Jiménez-Venegas
- Faculty of Agricultural Sciences, University of Chile, Santa Rosa 11315, La Pintana, Santiago 8820808, Chile; (J.J.-V.); (Y.T.)
- Master Program in Territorial Management of Natural Resources, University of Chile, Santa Rosa 11315, La Pintana, Santiago 8820808, Chile
| | - Leonardo Zamora-Leiva
- Fundación Bionostra Chile Research, Almirante Lynch 1179, San Miguel, Santiago 8920033, Chile; (L.Z.-L.); (L.U.); (J.S.)
| | - Luciano Univaso
- Fundación Bionostra Chile Research, Almirante Lynch 1179, San Miguel, Santiago 8920033, Chile; (L.Z.-L.); (L.U.); (J.S.)
| | - Jorge Soto
- Fundación Bionostra Chile Research, Almirante Lynch 1179, San Miguel, Santiago 8920033, Chile; (L.Z.-L.); (L.U.); (J.S.)
| | - Yasna Tapia
- Faculty of Agricultural Sciences, University of Chile, Santa Rosa 11315, La Pintana, Santiago 8820808, Chile; (J.J.-V.); (Y.T.)
| | - Manuel Paneque
- Faculty of Agricultural Sciences, University of Chile, Santa Rosa 11315, La Pintana, Santiago 8820808, Chile; (J.J.-V.); (Y.T.)
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Olaya‐Abril A, Biełło K, Rodríguez‐Caballero G, Cabello P, Sáez LP, Moreno‐Vivián C, Luque‐Almagro VM, Roldán MD. Bacterial tolerance and detoxification of cyanide, arsenic and heavy metals: Holistic approaches applied to bioremediation of industrial complex wastes. Microb Biotechnol 2024; 17:e14399. [PMID: 38206076 PMCID: PMC10832572 DOI: 10.1111/1751-7915.14399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Cyanide is a highly toxic compound that is found in wastewaters generated from different industrial activities, such as mining or jewellery. These residues usually contain high concentrations of other toxic pollutants like arsenic and heavy metals that may form different complexes with cyanide. To develop bioremediation strategies, it is necessary to know the metabolic processes involved in the tolerance and detoxification of these pollutants, but most of the current studies are focused on the characterization of the microbial responses to each one of these environmental hazards individually, and the effect of co-contaminated wastes on microbial metabolism has been hardly addressed. This work summarizes the main strategies developed by bacteria to alleviate the effects of cyanide, arsenic and heavy metals, analysing interactions among these toxic chemicals. Additionally, it is discussed the role of systems biology and synthetic biology as tools for the development of bioremediation strategies of complex industrial wastes and co-contaminated sites, emphasizing the importance and progress derived from meta-omic studies.
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Affiliation(s)
- Alfonso Olaya‐Abril
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Karolina Biełło
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Gema Rodríguez‐Caballero
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Purificación Cabello
- Departamento de Botánica, Ecología y Fisiología Vegetal, Edificio Celestino Mutis, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Lara P. Sáez
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Conrado Moreno‐Vivián
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - Víctor Manuel Luque‐Almagro
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
| | - María Dolores Roldán
- Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa, Campus de RabanalesUniversidad de CórdobaCórdobaSpain
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Zappa S, Berne C, Morton RI, De Stercke J, Brun YV. The HmrABCX pathway regulates the transition between motile and sessile lifestyles in Caulobacter crescentus by a HfiA-independent mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571505. [PMID: 38168291 PMCID: PMC10760086 DOI: 10.1101/2023.12.13.571505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Through its cell cycle, the bacterium Caulobacter crescentus switches from a motile, free-living state, to a sessile surface-attached cell. During this coordinated process, cells undergo irreversible morphological changes, such as shedding of their polar flagellum and synthesis of an adhesive holdfast at the same pole. In this work, we used genetic screens to identify genes involved in the regulation of the motile to sessile lifestyle transition. We identified a predicted hybrid histidine kinase that inhibits biofilm formation and activates the motile lifestyle: HmrA (Holdfast and motility regulator A). Genetic screens and genomic localization led to the identification of additional genes that regulate the proportion of cells harboring an active flagellum or a holdfast and that form a putative phosphorelay pathway with HmrA. Further genetic analysis indicates that the Hmr pathway is independent of the holdfast synthesis regulator HfiA and may impact c-di-GMP synthesis through the diguanylate cyclase DgcB pathway. Finally, we provide evidence that the Hmr pathway is involved in the regulation of sessile-to-motile lifestyle as a function of environmental stresses, namely excess copper and non-optimal temperatures.
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Affiliation(s)
- Sébastien Zappa
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
| | - Cecile Berne
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
| | - Robert I. Morton
- Department of Biology, Indiana University, Bloomington, IN, USA
- Present address: Boston Scientific, Yokneam, Northern, ISRAEL
| | - Jonathan De Stercke
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
- Present address: Unité de Recherche en Biologie des Micro-organismes, Université de Namur, 61 rue de Bruxelles, B-5000 Namur, BELGIUM
| | - Yves V. Brun
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
- Department of Biology, Indiana University, Bloomington, IN, USA
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Louis G, Cherry P, Michaux C, Rahuel-Clermont S, Dieu M, Tilquin F, Maertens L, Van Houdt R, Renard P, Perpete E, Matroule JY. A cytoplasmic chemoreceptor and reactive oxygen species mediate bacterial chemotaxis to copper. J Biol Chem 2023; 299:105207. [PMID: 37660909 PMCID: PMC10579534 DOI: 10.1016/j.jbc.2023.105207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 08/16/2023] [Accepted: 08/23/2023] [Indexed: 09/05/2023] Open
Abstract
Chemotaxis is a widespread strategy used by unicellular and multicellular living organisms to maintain their fitness in stressful environments. We previously showed that bacteria can trigger a negative chemotactic response to a copper (Cu)-rich environment. Cu ion toxicity on bacterial cell physiology has been mainly linked to mismetallation events and reactive oxygen species (ROS) production, although the precise role of Cu-generated ROS remains largely debated. Here, using inductively coupled plasma optical emission spectrometry on cell fractionates, we found that the cytoplasmic Cu ion content mirrors variations of the extracellular Cu ion concentration. ROS-sensitive fluorescent probe and biosensor allowed us to show that the increase of cytoplasmic Cu ion content triggers a dose-dependent oxidative stress, which can be abrogated by superoxide dismutase and catalase overexpression. The inhibition of ROS production in the cytoplasm not only improves bacterial growth but also impedes Cu chemotaxis, indicating that ROS derived from cytoplasmic Cu ions mediate the control of bacterial chemotaxis to Cu. We also identified the Cu chemoreceptor McpR, which binds Cu ions with low affinity, suggesting a labile interaction. In addition, we demonstrate that the cysteine 75 and histidine 99 within the McpR sensor domain are key residues in Cu chemotaxis and Cu coordination. Finally, we discovered that in vitro both Cu(I) and Cu(II) ions modulate McpR conformation in a distinct manner. Overall, our study provides mechanistic insights on a redox-based control of Cu chemotaxis, indicating that the cellular redox status can play a key role in bacterial chemotaxis.
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Affiliation(s)
- Gwennaëlle Louis
- Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium
| | - Pauline Cherry
- Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium
| | - Catherine Michaux
- Laboratoire de Chimie Physique des Biomolécules, Namur Research Institute for Life Sciences (NARILIS) and Namur Institute of Structured Matter (NISM), University of Namur, Namur, Belgium
| | | | - Marc Dieu
- MaSUN, Mass Spectrometry Facility, University of Namur, Namur, Belgium
| | - Françoise Tilquin
- Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium
| | - Laurens Maertens
- Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium; Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Rob Van Houdt
- Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Patricia Renard
- MaSUN, Mass Spectrometry Facility, University of Namur, Namur, Belgium
| | - Eric Perpete
- Laboratoire de Chimie Physique des Biomolécules, Namur Research Institute for Life Sciences (NARILIS) and Namur Institute of Structured Matter (NISM), University of Namur, Namur, Belgium
| | - Jean-Yves Matroule
- Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
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