1
|
Miralles-Robledillo JM, Martínez-Espinosa RM, Pire C. Transcriptomic profiling of haloarchaeal denitrification through RNA-Seq analysis. Appl Environ Microbiol 2024:e0057124. [PMID: 38814058 DOI: 10.1128/aem.00571-24] [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: 03/27/2024] [Accepted: 04/26/2024] [Indexed: 05/31/2024] Open
Abstract
Denitrification, a crucial biochemical pathway prevalent among haloarchaea in hypersaline ecosystems, has garnered considerable attention in recent years due to its ecological implications. Nevertheless, the underlying molecular mechanisms and genetic regulation governing this respiration/detoxification process in haloarchaea remain largely unexplored. In this study, RNA-sequencing was used to compare the transcriptomes of the haloarchaeon Haloferax mediterranei under oxic and denitrifying conditions, shedding light on the intricate metabolic alterations occurring within the cell, such as the accurate control of the metal homeostasis. Furthermore, the investigation identifies several genes encoding transcriptional regulators and potential accessory proteins with putative roles in denitrification. Among these are bacterioopsin-like transcriptional activators, proteins harboring a domain of unknown function (DUF2249), and cyanoglobin. In addition, the study delves into the genetic regulation of denitrification, finding a regulatory motif within promoter regions that activates numerous denitrification-related genes. This research serves as a starting point for future molecular biology studies in haloarchaea, offering a promising avenue to unravel the intricate mechanisms governing haloarchaeal denitrification, a pathway of paramount ecological importance.IMPORTANCEDenitrification, a fundamental process within the nitrogen cycle, has been subject to extensive investigation due to its close association with anthropogenic activities, and its contribution to the global warming issue, mainly through the release of N2O emissions. Although our comprehension of denitrification and its implications is generally well established, most studies have been conducted in non-extreme environments with mesophilic microorganisms. Consequently, there is a significant knowledge gap concerning extremophilic denitrifiers, particularly those inhabiting hypersaline environments. The significance of this research was to delve into the process of haloarchaeal denitrification, utilizing the complete denitrifier haloarchaeon Haloferax mediterranei as a model organism. This research led to the analysis of the metabolic state of this microorganism under denitrifying conditions and the identification of regulatory signals and genes encoding proteins potentially involved in this pathway, serving as a valuable resource for future molecular studies.
Collapse
Affiliation(s)
- Jose María Miralles-Robledillo
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
| | - Rosa María Martínez-Espinosa
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
| | - Carmen Pire
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
| |
Collapse
|
2
|
Gelsinger DR, Reddy R, Whittington K, Debic S, DiRuggiero J. Post-transcriptional regulation of redox homeostasis by the small RNA SHOxi in haloarchaea. RNA Biol 2021; 18:1867-1881. [PMID: 33522404 PMCID: PMC8583180 DOI: 10.1080/15476286.2021.1874717] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 01/06/2021] [Accepted: 01/07/2021] [Indexed: 11/13/2022] Open
Abstract
While haloarchaea are highly resistant to oxidative stress, a comprehensive understanding of the processes regulating this remarkable response is lacking. Oxidative stress-responsive small non-coding RNAs (sRNAs) have been reported in the model archaeon, Haloferax volc anii, but targets and mechanisms have not been elucidated. Using a combination of high throughput and reverse molecular genetic approaches, we elucidated the functional role of the most up-regulated intergenic sRNA during oxidative stress in H. volcanii, named Small RNA in Haloferax Oxidative Stress (SHOxi). SHOxi was predicted to form a stable secondary structure with a conserved stem-loop region as the potential binding site for trans-targets. NAD-dependent malic enzyme mRNA, identified as a putative target of SHOxi, interacted directly with a putative 'seed' region within the predicted stem loop of SHOxi. Malic enzyme catalyzes the oxidative decarboxylation of malate into pyruvate using NAD+ as a cofactor. The destabilization of malic enzyme mRNA, and the decrease in the NAD+/NADH ratio, resulting from the direct RNA-RNA interaction between SHOxi and its trans-target was essential for the survival of H. volcanii to oxidative stress. These findings indicate that SHOxi likely regulates redox homoeostasis during oxidative stress by the post-transcriptional destabilization of malic enzyme mRNA. SHOxi-mediated regulation provides evidence that the fine-tuning of metabolic cofactors could be a core strategy to mitigate damage from oxidative stress and confer resistance. This study is the first to establish the regulatory effects of sRNAs on mRNAs during the oxidative stress response in Archaea.
Collapse
Affiliation(s)
| | - Rahul Reddy
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Sara Debic
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Jocelyne DiRuggiero
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland, USA
| |
Collapse
|
3
|
Rodríguez-Herrero V, Peris A, Camacho M, Bautista V, Esclapez J, Bonete MJ. Novel Glutamate-Putrescine Ligase Activity in Haloferax mediterranei: A New Function for glnA-2 Gene. Biomolecules 2021; 11:biom11081156. [PMID: 34439822 PMCID: PMC8394153 DOI: 10.3390/biom11081156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/25/2021] [Accepted: 07/31/2021] [Indexed: 02/06/2023] Open
Abstract
The genome of the halophilic archaea Haloferax mediterranei contains three ORFs that show homology with glutamine synthetase (GS) (glnA-1, glnA-2, and glnA-3). Previous studies have focused on the role of GlnA-1, suggesting that proteins GlnA-2 and GlnA-3 could play a different role to that of GS. Glutamine synthetase (EC 6.3.1.2) belongs to the class of ligases, including 20 subclasses of other different enzymes, such as aspartate–ammonia ligase (EC 6.3.1.1), glutamate–ethylamine ligase (EC 6.3.1.6), and glutamate–putrescine ligase (EC 6.3.1.11). The reaction catalyzed by glutamate–putrescine ligase is comparable to the reaction catalyzed by glutamine synthetase (GS). Both enzymes can bind a glutamate molecule to an amino group: ammonium (GS) or putrescine (glutamate–putrescine ligase). In addition, they present the characteristic catalytic domain of GS, showing significant similarities in their structure. Although these proteins are annotated as GS, the bioinformatics and experimental results obtained in this work indicate that the GlnA-2 protein (HFX_1688) is a glutamate–putrescine ligase, involved in polyamine catabolism. The most significant results are those related to glutamate–putrescine ligase’s activity and the analysis of the transcriptional and translational expression of the glnA-2 gene in the presence of different nitrogen sources. This work confirms a new metabolic pathway in the Archaea domain which extends the knowledge regarding the utilization of alternative nitrogen sources in this domain.
Collapse
Affiliation(s)
- Verónica Rodríguez-Herrero
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Division, Faculty of Science, University of Alicante, 03080 Alicante, Spain; (V.R.-H.); (M.C.); (V.B.)
| | - Arnau Peris
- Institute for Integrative Systems Biology, I2SysBio, Campus Burjassot, University of Valencia-CSIC, 46908 Valencia, Spain;
| | - Mónica Camacho
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Division, Faculty of Science, University of Alicante, 03080 Alicante, Spain; (V.R.-H.); (M.C.); (V.B.)
| | - Vanesa Bautista
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Division, Faculty of Science, University of Alicante, 03080 Alicante, Spain; (V.R.-H.); (M.C.); (V.B.)
| | - Julia Esclapez
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Division, Faculty of Science, University of Alicante, 03080 Alicante, Spain; (V.R.-H.); (M.C.); (V.B.)
- Correspondence: (J.E.); (M.-J.B.); Tel.: +34-965-903-880 (J.E. & M.-J.B.)
| | - María-José Bonete
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Division, Faculty of Science, University of Alicante, 03080 Alicante, Spain; (V.R.-H.); (M.C.); (V.B.)
- Correspondence: (J.E.); (M.-J.B.); Tel.: +34-965-903-880 (J.E. & M.-J.B.)
| |
Collapse
|
4
|
Payá G, Bautista V, Camacho M, Bonete MJ, Esclapez J. Functional analysis of Lsm protein under multiple stress conditions in the extreme haloarchaeon Haloferax mediterranei. Biochimie 2021; 187:33-47. [PMID: 33992715 DOI: 10.1016/j.biochi.2021.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 01/24/2023]
Abstract
The Sm, like-Sm, and Hfq proteins belonging to the Sm superfamily of proteins are represented in all domains of life. These proteins are involved in several RNA metabolism pathways. The functions of bacterial Hfq and eukaryotic Sm proteins have been described, but knowledge about the in vivo functions of archaeal Sm proteins remains limited. This study aims to improve the understanding of Lsm proteins and their role using the haloarchaeon Haloferax mediterranei as a model microorganism. The Haloferax mediterranei genome contains one lsm gene that overlaps with the rpl37e gene. To determine the expression of lsm and rpl37e genes and the co-transcription of both, reverse transcription-polymerase chain reaction (RT-PCR) analyses were performed under different standard and stress conditions. The results suggest that the expression of lsm and rpl37e is constitutive. Co-transcription occurs at sub-optimal salt concentrations and temperatures, depending on the growth phase. The halophilic Lsm protein contains two Sm motifs, Sm1 and Sm2, and the sequence encoding the Sm2 motif also constitutes the promoter of the rpl37e gene. To investigate their biological functions, the lsm deletion mutant and the Sm1 motif deletion mutant, where the Sm2 motif remained intact, were generated and characterised. Comparison of the lsm deletion mutant, Sm1 deletion mutant, and the parental strain HM26 under standard and stress growth conditions revealed growth differences. Finally, swarming assays in complex and defined media showed greater swarming capacity in the deletion mutants.
Collapse
Affiliation(s)
- Gloria Payá
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Vanesa Bautista
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Mónica Camacho
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - María-José Bonete
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Julia Esclapez
- Agrochemistry and Biochemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| |
Collapse
|