The C-terminal region of phytoene synthase is a key element to control carotenoid biosynthesis in the haloarchaeon Haloferax volcanii.

Phytoene synthase (PSY) converts two molecules of geranyl-geranyl diphosphate to phytoene, the key regulatory step in carotenogenesis. However, post-translational mechanisms that control PSY expression are scarcely understood. Carotenoid biosynthesis (mainly bacterioruberin) is a distinctive feature of haloarchaea thriving in hypersaline environments.

Carotenoids from Haloarchaea: Extraction, Fractionation, and Characterization.

Carotenoids are bioactive molecules known to promote human health. Many extreme halophilic archaea synthesize carotenoids, mainly represented by C bacterioruberin (BR) and its derivatives. BR has a potent antioxidant capacity, even higher than that of β-carotene, thus, there is an increasing interest to advance the study of its biological properties as well as to extend its current applications.

Proteolytic Activity Assays in Haloarchaea.

Extreme halophilic archaea (haloarchaea) have adapted their physiology and biomolecules to thrive in saline environments (>2 M NaCl). Many haloarchaea produce extracellular hydrolases (including proteases) with potential biotechnological applications, which require unusual high salt concentrations to attain their function and maintain their stability. These conditions restrict many of the standard methods used to study these enzymes such as activity determination and/or protein purification.

Proteomic Study of the Exponential-Stationary Growth Phase Transition in the Haloarchaea Natrialba magadii and Haloferax volcanii.

The dynamic changes that take place along the phases of microbial growth (lag, exponential, stationary, and death) have been widely studied in bacteria at the molecular and cellular levels, but little is known for archaea. In this study, a high-throughput approach was used to analyze and compare the proteomes of two haloarchaea during exponential and stationary growth: the neutrophilic Haloferax volcanii and the alkaliphilic Natrialba magadii. Almost 2000 proteins were identified in each species (≈50% of the predicted proteome).

Functional roles of C-terminal extension (CTE) of salt-dependent peptidase activity of the Natrialba magadii extracellular protease (NEP).

Nep (Natrialba magadii extracellular protease) is a halolysin-like peptidase secreted by the haloalkaliphilic archaeon Natrialba magadii. Many extracellular proteases have been characterized from archaea to bacteria as adapted to hypersaline environments retaining function and stability until 4.0M NaCl.

LonB Protease Is a Novel Regulator of Carotenogenesis Controlling Degradation of Phytoene Synthase in Haloferax volcanii.

The membrane protease LonB is an essential protein in the archaeon Haloferax volcanii and globally impacts its physiology. However, natural substrates of the archaeal Lon protease have not been identified. The whole proteome turnover was examined in a H.

Exploring the multiple biotechnological potential of halophilic microorganisms isolated from two Argentinean salterns.

The biodiversity and biotechnological potential of microbes from central Argentinean halophilic environments have been poorly explored. Salitral Negro and Colorada Grande salterns are neutral hypersaline basins exploded for NaCl extraction. As part of an ecological analysis of these environments, two bacterial and seven archaeal representatives were isolated, identified and examined for their biotechnological potential.

Global role of the membrane protease LonB in Archaea: Potential protease targets revealed by quantitative proteome analysis of a lonB mutant in Haloferax volcanii.

Unlabelled: The membrane-associated LonB protease is essential for viability in Haloferax volcanii, however, the cellular processes affected by this protease in archaea are unknown. In this study, the impact of a lon conditional mutation (down-regulation) on H. volcanii physiology was examined by comparing proteomes of parental and mutant cells using shotgun proteomics.

Archaeal membrane-associated proteases: insights on Haloferax volcanii and other haloarchaea.

The function of membrane proteases range from general house-keeping to regulation of cellular processes. Although the biological role of these enzymes in archaea is poorly understood, some of them are implicated in the biogenesis of the archaeal cell envelope and surface structures. The membrane-bound ATP-dependent Lon protease is essential for cell viability and affects membrane carotenoid content in Haloferax volcanii.

A simple technique to improve the resolution of membrane acidic proteins of the haloarchaeon Haloferax volcanii by 2D electrophoresis.

Proteins present in the archaeal cell envelope play key roles in a variety of processes necessary for survival in extreme environments. The haloarchaeon Haloferax volcanii is a good model for membrane proteomic studies because its genome sequence is known, it can be genetically manipulated, and a number of studies at the "omics" level have been performed in this organism. This work reports an easy strategy to improve the resolution of acidic membrane proteins from H.

A rhomboid protease gene deletion affects a novel oligosaccharide N-linked to the S-layer glycoprotein of Haloferax volcanii.

Rhomboid proteases occur in all domains of life; however, their physiological role is not completely understood, and nothing is known of the biology of these enzymes in Archaea. One of the two rhomboid homologs of Haloferax volcanii (RhoII) is fused to a zinc finger domain. Chromosomal deletion of rhoII was successful, indicating that this gene is not essential for this organism; however, the mutant strain (MIG1) showed reduced motility and increased sensitivity to novobiocin.

The LonB protease controls membrane lipids composition and is essential for viability in the extremophilic haloarchaeon Haloferax volcanii.

Although homologs of the ATP-dependent Lon protease exist in all domains of life, the relevance of this protease in archaeal physiology remains a mystery. In this study, we have constructed and phenotypically characterized deletion and conditional lon mutants in the model haloarchaeon Haloferax volcanii to elucidate the role of the unusual membrane-bound LonB protease in archaea. Hvlon could be deleted from the chromosome only when a copy of the wild type gene was provided in trans suggesting that Lon is essential for survival in this archaeon.

Novel inhibitory activity for serine protease inhibitor Kazal type-3 (Spink3) on human recombinant kallikreins.

Kallikrein-related peptidases (KLKs) are trypsin-like and chymotrypsin-like serine proteases which are expressed in several tissues. Their activity is tightly controlled by inhibitors including members of the serine protease Kazal-type (SPINK) family. These enzymes are promising targets for the treatment of skin desquamation, inflammation and cancer.

Autocatalytic maturation of the Tat-dependent halophilic subtilase Nep produced by the archaeon Natrialba magadii.

Halolysins are subtilisin-like extracellular proteases produced by haloarchaea that possess unique protein domains and are salt dependent for structural integrity and functionality. In contrast to bacterial subtilases, the maturation mechanism of halolysins has not been addressed. The halolysin Nep is secreted by the alkaliphilic haloarchaeon Natrialba magadii, and the recombinant active enzyme has been synthesized in Haloferax volcanii.

Correlation between catalysis and tertiary structure arrangement in an archaeal halophilic subtilase.

Nep (Natrialba magadii extracellular protease) is a halolysin-like peptidase secreted by the haloalkaliphilic archaeon N. magadii that exhibits optimal activity and stability in salt-saturated solutions. In this work, the effect of salt on the function and structure of Nep was investigated.

Chemotactic responses to gas oil of Halomonas spp. strains isolated from saline environments in Argentina.

In this study, two halophilic bacterial strains isolated from saline habitats in Argentina grew in the presence of gas oil. They were identified as Halomonas spp. and Nesterenkonia sp.

The Lon protease from the haloalkaliphilic archaeon Natrialba magadii is transcriptionally linked to a cluster of putative membrane proteases and displays DNA-binding activity.

The ATP-dependent Lon protease is universally distributed in bacteria, eukaryotic organelles and archaea. In comparison with bacterial and eukaryal Lon proteases, the biology of the archaeal Lon has been studied to a limited extent. In this study, the gene encoding the Lon protease of the alkaliphilic haloarchaeon Natrialba magadii (Nmlon) was cloned and sequenced, and the genetic organization of Nmlon was examined at the transcriptional level.