More Like this

1. A conserved transcription factor controls gluconeogenesis via distinct targets in hypersaline-adapted archaea with diverse metabolic capabilities

   https://doi.org/10.1371/journal.pgen.1011115  

   Hackley, Rylee K; Vreugdenhil-Hayslette, Angie; Darnell, Cynthia L; Schmid, Amy K (January 2024, PLOS Genetics)

   Albers, Sonja (Ed.)

   Timely regulation of carbon metabolic pathways is essential for cellular processes and to prevent futile cycling of intracellular metabolites. InHalobacterium salinarum, a hypersaline adapted archaeon, a sugar-sensing TrmB family protein controls gluconeogenesis and other biosynthetic pathways. Notably,Hbt. salinarumdoes not utilize carbohydrates for energy, uncommon among Haloarchaea. We characterized a TrmB-family transcriptional regulator in a saccharolytic generalist,Haloarcula hispanica, to investigate whether the targets and function of TrmB, or its regulon, is conserved in related species with distinct metabolic capabilities. InHar. hispanica, TrmB binds to 15 sites in the genome and induces the expression of genes primarily involved in gluconeogenesis and tryptophan biosynthesis. An important regulatory control point inHbt. salinarum, activation ofppsAand repression ofpykA, is absent inHar. hispanica. Contrary to its role inHbt. salinarumand saccharolytic hyperthermophiles, TrmB does not act as a global regulator: it does not directly repress the expression of glycolytic enzymes, peripheral pathways such as cofactor biosynthesis, or catabolism of other carbon sources inHar. hispanica. Cumulatively, these findings suggest rewiring of the TrmB regulon alongside metabolic network evolution in Haloarchaea. 

   more » « less
2. The Hypersaline Archaeal Histones HpyA and HstA Are DNA Binding Proteins That Defy Categorization According to Commonly Used Functional Criteria

   https://doi.org/10.1128/mbio.03449-22  

   Sakrikar, Saaz; Hackley, Rylee K.; Martinez-Pastor, Mar; Darnell, Cynthia L.; Vreugdenhil, Angie; Schmid, Amy K. (April 2023, mBio)

   Komeili, Arash (Ed.)

   ABSTRACT Histone proteins are found across diverse lineages of Archaea , many of which package DNA and form chromatin. However, previous research has led to the hypothesis that the histone-like proteins of high-salt-adapted archaea, or halophiles, function differently. The sole histone protein encoded by the model halophilic species Halobacterium salinarum , HpyA, is nonessential and expressed at levels too low to enable genome-wide DNA packaging. Instead, HpyA mediates the transcriptional response to salt stress. Here we compare the features of genome-wide binding of HpyA to those of HstA, the sole histone of another model halophile, Haloferax volcanii . hstA , like hpyA , is a nonessential gene. To better understand HpyA and HstA functions, protein-DNA binding data (chromatin immunoprecipitation sequencing [ChIP-seq]) of these halophilic histones are compared to publicly available ChIP-seq data from DNA binding proteins across all domains of life, including transcription factors (TFs), nucleoid-associated proteins (NAPs), and histones. These analyses demonstrate that HpyA and HstA bind the genome infrequently in discrete regions, which is similar to TFs but unlike NAPs, which bind a much larger genomic fraction. However, unlike TFs that typically bind in intergenic regions, HpyA and HstA binding sites are located in both coding and intergenic regions. The genome-wide dinucleotide periodicity known to facilitate histone binding was undetectable in the genomes of both species. Instead, TF-like and histone-like binding sequence preferences were detected for HstA and HpyA, respectively. Taken together, these data suggest that halophilic archaeal histones are unlikely to facilitate genome-wide chromatin formation and that their function defies categorization as a TF, NAP, or histone. IMPORTANCE Most cells in eukaryotic species—from yeast to humans—possess histone proteins that pack and unpack DNA in response to environmental cues. These essential proteins regulate genes necessary for important cellular processes, including development and stress protection. Although the histone fold domain originated in the domain of life Archaea , the function of archaeal histone-like proteins is not well understood relative to those of eukaryotes. We recently discovered that, unlike histones of eukaryotes, histones in hypersaline-adapted archaeal species do not package DNA and can act as transcription factors (TFs) to regulate stress response gene expression. However, the function of histones across species of hypersaline-adapted archaea still remains unclear. Here, we compare hypersaline histone function to a variety of DNA binding proteins across the tree of life, revealing histone-like behavior in some respects and specific transcriptional regulatory function in others. 

   more » « less
3. TbsP and TrmB jointly regulate gapII to influence cell development phenotypes in the archaeon Haloferax volcanii

   https://doi.org/10.1111/mmi.15225  

   Hackley, Rylee K.; Hwang, Sungmin; Herb, Jake T.; Bhanap, Preeti; Lam, Katie; Vreugdenhil, Angie; Darnell, Cynthia L.; Pastor, Mar Martinez; Martin, Johnathan H.; Maupin‐Furlow, Julie A.; et al (January 2024, Molecular Microbiology)

   Abstract Microbial cells must continually adapt their physiology in the face of changing environmental conditions. Archaea living in extreme conditions, such as saturated salinity, represent important examples of such resilience. The model salt‐loving organismHaloferax volcaniiexhibits remarkable plasticity in its morphology, biofilm formation, and motility in response to variations in nutrients and cell density. However, the mechanisms regulating these lifestyle transitions remain unclear. In prior research, we showed that the transcriptional regulator, TrmB, maintains the rod shape in the related speciesHalobacterium salinarumby activating the expression of enzyme‐coding genes in the gluconeogenesis metabolic pathway. InHbt. salinarum, TrmB‐dependent production of glucose moieties is required for cell surface glycoprotein biogenesis. Here, we use a combination of genetics and quantitative phenotyping assays to demonstrate that TrmB is essential for growth under gluconeogenic conditions inHfx. volcanii. The ∆trmBstrain rapidly accumulated suppressor mutations in a gene encoding a novel transcriptional regulator, which we nametrmBsuppressor, or TbsP (a.k.a. “tablespoon”). TbsP is required for adhesion to abiotic surfaces (i.e., biofilm formation) and maintains wild‐type cell morphology and motility. We use functional genomics and promoter fusion assays to characterize the regulons controlled by each of TrmB and TbsP, including joint regulation of the glucose‐dependent transcription ofgapII, which encodes an important gluconeogenic enzyme. We conclude that TrmB and TbsP coregulate gluconeogenesis, with downstream impacts on lifestyle transitions in response to nutrients inHfx. volcanii. 

   more » « less
4. Similar mutation rates but different mutation spectra in moderate and extremely halophilic archaea

   https://doi.org/10.1093/g3journal/jkac303  

   Kucukyildirim, Sibel; Ozdemirel, Huseyin Ozgur; Lynch, Michael (December 2022, G3 Genes|Genomes|Genetics)

   Wong, A (Ed.)

   Abstract Archaea are a major part of Earth’s microbiota and extremely diverse. Yet, we know very little about the process of mutation that drives such diversification. To expand beyond previous work with the moderate halophilic archaeal species Haloferax volcanii, we performed a mutation-accumulation experiment followed by whole-genome sequencing in the extremely halophilic archaeon Halobacterium salinarum. Although Hfx. volcanii and Hbt. salinarum have different salt requirements, both species have highly polyploid genomes and similar GC content. We accumulated mutations for an average of 1250 generations in 67 mutation accumulation lines of Hbt. salinarum, and revealed 84 single-base substitutions and 10 insertion-deletion mutations. The estimated base-substitution mutation rate of 3.99 × 10−10 per site per generation or 1.0 × 10−3 per genome per generation in Hbt. salinarum is similar to that reported for Hfx. volcanii (1.2 × 10−3 per genome per generation), but the genome-wide insertion-deletion rate and spectrum of mutations are somewhat dissimilar in these archaeal species. The spectra of spontaneous mutations were AT biased in both archaea, but they differed in significant ways that may be related to differences in the fidelity of DNA replication/repair mechanisms or a simple result of the different salt concentrations. 

   more » « less
5. A comprehensive spectral assay library to quantify the Halobacterium salinarum NRC-1 proteome by DIA/SWATH-MS

   https://doi.org/10.1038/s41597-023-02590-5  

   Kusebauch, Ulrike; Lorenzetti, Alan P. R.; Campbell, David S.; Pan, Min; Shteynberg, David; Kapil, Charu; Midha, Mukul K.; López García de Lomana, Adrián; Baliga, Nitin S.; Moritz, Robert L. (October 2023, Scientific Data)

   Abstract Data-Independent Acquisition (DIA) is a mass spectrometry-based method to reliably identify and reproducibly quantify large fractions of a target proteome. The peptide-centric data analysis strategy employed in DIA requiresa priorigenerated spectral assay libraries. Such assay libraries allow to extract quantitative data in a targeted approach and have been generated for human, mouse, zebrafish,E. coliand few other organisms. However, a spectral assay library for the extreme halophilic archaeonHalobacterium salinarumNRC-1, a model organism that contributed to several notable discoveries, is not publicly available yet. Here, we report a comprehensive spectral assay library to measure 2,563 of 2,646 annotatedH. salinarumNRC-1 proteins. We demonstrate the utility of this library by measuring global protein abundances over time under standard growth conditions. TheH. salinarumNRC-1 library includes 21,074 distinct peptides representing 97% of the predicted proteome and provides a new, valuable resource to confidently measure and quantify any protein of this archaeon. Data and spectral assay libraries are available via ProteomeXchange (PXD042770, PXD042774) and SWATHAtlas (SAL00312-SAL00319). 

   more » « less