Understanding the tolerance of halophilic archaea to stress landscapes.

Haloarchaea, known for their resilience to environmental fluctuations, require a minimum salt concentration of 10% (w/v) for growth and can survive up to 35% (w/v) salinity. In biotechnology, these halophiles have diverse industrial applications. This study investigates the tolerance responses of nine haloarchaea: Haloferax mediterranei, Haloferax volcanii, Haloferax gibbonsii, Halorubrum californiense, Halorubrum litoreum, Natrinema pellirubrum, Natrinema altunense, Haloterrigena thermotolerans and Haloarcula sinaiiensis, under various stressful conditions.

Global Lrp regulator protein from Haloferax mediterranei: Transcriptional analysis and structural characterization.

Haloferax mediterranei, an extreme halophilic archaeon thriving in hypersaline environments, has acquired significant attention in biotechnological and biochemical research due to its remarkable ability to flourish in extreme salinity conditions. Transcription factors, essential in regulating diverse cellular processes, have become focal points in understanding its adaptability. This study delves into the role of the Lrp transcription factor, exploring its modulation of glnA, nasABC, and lrp gene promoters in vivo through β-galactosidase assays.

Deepening the knowledge of universal stress proteins in Haloferax mediterranei.

Haloarchaea, like many other microorganisms, have developed defense mechanisms such as universal stress proteins (USPs) to cope with environmental stresses affecting microbial growth. Despite the wide distribution of these proteins in Archaea, their biochemical characteristics still need to be discovered, and there needs to be more knowledge about them focusing on halophilic Archaea. Therefore, elucidating the role of USPs would provide valuable information to improve future biotechnological applications.

Analysis of Lsm Protein-Mediated Regulation in the Haloarchaeon .

The Sm protein superfamily includes Sm, like-Sm (Lsm), and Hfq found in the , , and domains. Archaeal Lsm proteins have been shown to bind sRNAs and are probably involved in various cellular processes, suggesting a similar function in regulating sRNAs by Hfq in bacteria. Moreover, archaeal Lsm proteins probably represent the ancestral Lsm domain from which eukaryotic Sm proteins have evolved.

Genome-wide transcriptional response to silver stress in extremely halophilic archaeon Haloferax alexandrinus DSM 27206.

Background: The extremely halophilic archaeon Haloferax (Hfx.) alexandrinus DSM 27206 was previously documented for the ability to biosynthesize silver nanoparticles while mechanisms underlying its silver tolerance were overlooked. In the current study, we aimed to assess the transcriptional response of this haloarchaeon to varying concentrations of silver, seeking a comprehensive understanding of the molecular determinants underpinning its heavy metal tolerance.

Comprehensive Bioinformatics Analysis of the Biodiversity of Lsm Proteins in the Domain.

The Sm protein superfamily includes Sm, like-Sm (Lsm), and Hfq proteins. Sm and Lsm proteins are found in the and domains, respectively, while Hfq proteins exist in the domain. Even though Sm and Hfq proteins have been extensively studied, archaeal Lsm proteins still require further exploration.

Archaea: current and potential biotechnological applications.

Archaea are microorganisms with great ability to colonize some of the most inhospitable environments in nature, managing to survive in places with extreme characteristics for most microorganisms. Its proteins and enzymes are stable and can act under extreme conditions in which other proteins and enzymes would degrade. These attributes make them ideal candidates for use in a wide range of biotechnological applications.

Lrp as a potential transcriptional regulator involved in stress response in Haloferax mediterranei.

The Archaea domain consists of a heterogeneous group of microorganisms with unique physiological properties that occupy a wide variety of niches in nature. Haloferax mediterranei is an extremely halophilic archaeon classified in the Phylum Euryarchaeota, which requires a high concentration of inorganic salts for optimal growth. In haloarchaea, transcription factors play a fundamental role in an adequate adaptation to environmental and nutritional changes, preserving the survival and integrity of the organism.

Characterization and biological activities of carotenoids produced by three haloarchaeal strains isolated from Algerian salt lakes.

Halophilic archaea represent a promising natural source of carotenoids. However, little information is available about these archaeal metabolites and their biological effects. In the present work, carotenoids of strains Haloferax sp.

Novel Glutamate-Putrescine Ligase Activity in : A New Function for Gene.

The genome of the halophilic archaea contains three ORFs that show homology with glutamine synthetase (GS) (, , and ). 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.

Analysis of Lrp Transcriptional Regulator.

is an extremely halophilic archaeon, able to live in hypersaline environments with versatile nutritional requirements, whose study represents an excellent basis in the field of biotechnology. The transcriptional machinery in combines the eukaryotic basal apparatus and the bacterial regulation mechanisms. However, little is known about molecular mechanisms of gene expression regulation compared with , particularly in Haloarchaea.

Functional analysis of Lsm protein under multiple stress conditions in the extreme haloarchaeon Haloferax mediterranei.

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.

Towards the Elucidation of Assimilative Operon Transcriptional Regulation in .

The assimilatory pathway of the nitrogen cycle in the haloarchaeon has been well described and characterized in previous studies. However, the regulatory mechanisms involved in the gene expression of this pathway remain unknown in haloarchaea. This work focuses on elucidating the regulation at the transcriptional level of the assimilative operon (HFX_2002 to HFX_2004) through different approaches.

The Survival of under Stressful Conditions.

Haloarchaea can survive and thrive under exposure to a wide range of extreme environmental factors, which represents a potential interest to biotechnology. Growth responses to different stressful conditions were examined in the haloarchaeon R4. It has been demonstrated that this halophilic archaeon is able to grow between 10 and 32.

The Role of Stress Proteins in Haloarchaea and Their Adaptive Response to Environmental Shifts.

Over the years, in order to survive in their natural environment, microbial communities have acquired adaptations to nonoptimal growth conditions. These shifts are usually related to stress conditions such as low/high solar radiation, extreme temperatures, oxidative stress, pH variations, changes in salinity, or a high concentration of heavy metals. In addition, climate change is resulting in these stress conditions becoming more significant due to the frequency and intensity of extreme weather events.

Bioprospecting and characterization of pigmented halophilic archaeal strains from Algerian hypersaline environments with analysis of carotenoids produced by Halorubrum sp. BS2.

A set of 110 extremely halophilic archaeal strains were isolated from seven distinct saline habitats located in different regions of Algeria. The physicochemical characterization of the samples showed that these habitats were thalassohaline. The carotenoid production from isolated strains varied from 0.

New proposal of nitrogen metabolism regulation by small RNAs in the extreme halophilic archaeon Haloferax mediterranei.

The regulatory networks involved in the uptake and metabolism of different nitrogen sources in response to their availability are crucial in all organisms. Nitrogen metabolism pathways have been studied in detail in archaea such as the extreme halophilic archaeon Haloferax mediterranei. However, knowledge about nitrogen metabolism regulation in haloarchaea is very scarce, and no transcriptional regulators involved in nitrogen metabolism have been identified to date.

Small RNAs of Haloferax mediterranei: Identification and Potential Involvement in Nitrogen Metabolism.

Small RNAs have been studied in detail in domains Bacteria and Eukarya but, in the case of the domain Archaea, the knowledge is scarce and the physiological function of these small RNAs (sRNAs) is still uncertain. To extend the knowledge of sRNAs in the domain Archaea and their possible role in the regulation of the nitrogen assimilation metabolism in haloarchaea, has been used as a model microorganism. The bioinformatic approach has allowed for the prediction of 295 putative sRNAs genes in the genome of , 88 of which have been verified by means of RNA-Sequencing (RNA-Seq).

Analysis of multiple haloarchaeal genomes suggests that the quinone-dependent respiratory nitric oxide reductase is an important source of nitrous oxide in hypersaline environments.

Microorganisms, including Bacteria and Archaea, play a key role in denitrification, which is the major mechanism by which fixed nitrogen returns to the atmosphere from soil and water. While the enzymology of denitrification is well understood in Bacteria, the details of the last two reactions in this pathway, which catalyse the reduction of nitric oxide (NO) via nitrous oxide (N O) to nitrogen (N ), are little studied in Archaea, and hardly at all in haloarchaea. This work describes an extensive interspecies analysis of both complete and draft haloarchaeal genomes aimed at identifying the genes that encode respiratory nitric oxide reductases (Nors).

Effects of nitrogen sources on the nitrate assimilation in Haloferax mediterranei: growth kinetics and transcriptomic analysis.

The haloarchaeon Haloferax mediterranei is able to grow in a defined culture media not only in the presence of inorganic nitrogen salt but also with amino acid as the sole nitrogen source. Assimilatory nitrate and nitrite reductases, respectively, catalyze the first and second reactions. The genes involved in this process are nasA, which encodes nitrate reductase and is found within the operon nasABC, and nasD, which encodes nitrite reductase.

Cyclodextrin glycosyltransferase: a key enzyme in the assimilation of starch by the halophilic archaeon Haloferax mediterranei.

A cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.

Active site dynamics in the zinc-dependent medium chain alcohol dehydrogenase superfamily.

Despite being the subject of intensive investigations, many aspects of the mechanism of the zinc-dependent medium chain alcohol dehydrogenase (MDR) superfamily remain contentious. We have determined the high-resolution structures of a series of binary and ternary complexes of glucose dehydrogenase, an MDR enzyme from Haloferax mediterranei. In stark contrast to the textbook MDR mechanism in which the zinc ion is proposed to remain stationary and attached to a common set of protein ligands, analysis of these structures reveals that in each complex, there are dramatic differences in the nature of the zinc ligation.

An octameric prokaryotic glutamine synthetase from the haloarchaeon Haloferax mediterranei.

The glutamine synthetase (EC 6.3.1.