scholarly journals Cold Regulation of Genes Encoding Ion Transport Systems in the Oligotrophic Bacterium Caulobacter crescentus

2021 ◽  
Author(s):  
Hugo L. de Araújo ◽  
Bianca P. Martins ◽  
Alexandre M. Vicente ◽  
Alan P. R. Lorenzetti ◽  
Tie Koide ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Low Temperature ◽  
Ion Transport ◽  
Caulobacter Crescentus ◽  
Transport Systems ◽  
Acid Stability ◽  
Oligotrophic Bacterium ◽  
Genes Encoding ◽  
Cell Processes ◽  
Osmotic Balance

Low-temperature stress is an important factor for nucleic acid stability and must be circumvented in order to maintain the basic cell processes, such as transcription and translation. The oligotrophic lifestyle presents further challenges to ensure the proper nutrient uptake and osmotic balance in an environment of slow nutrient flow.

scholarly journals Transcriptional Profiling of Caulobacter crescentus during Growth on Complex and Minimal Media

2004 ◽  
Vol 186 (5) ◽  
pp. 1448-1461 ◽  
Author(s):  
Alison K. Hottes ◽  
Maliwan Meewan ◽  
Desiree Yang ◽  
Naomi Arana ◽  
Pedro Romero ◽  
...  
Keyword(s):  
Carbon Source ◽  
Mutational Analysis ◽  
Caulobacter Crescentus ◽  
Transcriptional Profiling ◽  
Transport Systems ◽  
Specific Expression ◽  
Induced Expression ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Minimal Media

ABSTRACT Microarray analysis was used to examine gene expression in the freshwater oligotrophic bacterium Caulobacter crescentus during growth on three standard laboratory media, including peptone-yeast extract medium (PYE) and minimal salts medium with glucose or xylose as the carbon source. Nearly 400 genes (approximately 10% of the genome) varied significantly in expression between at least two of these media. The differentially expressed genes included many encoding transport systems, most notably diverse TonB-dependent outer membrane channels of unknown substrate specificity. Amino acid degradation pathways constituted the largest class of genes induced in PYE. In contrast, many of the genes upregulated in minimal media encoded enzymes for synthesis of amino acids, including incorporation of ammonia and sulfate into glutamate and cysteine. Glucose availability induced expression of genes encoding enzymes of the Entner-Doudoroff pathway, which was demonstrated here through mutational analysis to be essential in C. crescentus for growth on glucose. Xylose induced expression of genes encoding several hydrolytic exoenzymes as well as an operon that may encode a novel pathway for xylose catabolism. A conserved DNA motif upstream of many xylose-induced genes was identified and shown to confer xylose-specific expression. Xylose is an abundant component of xylan in plant cell walls, and the microarray data suggest that in addition to serving as a carbon source for growth of C. crescentus, this pentose may be interpreted as a signal to produce enzymes associated with plant polymer degradation.

scholarly journals Environmental Conditions Modulate the Transcriptomic Response of Both Caulobacter crescentus Morphotypes to Cu Stress

2021 ◽  
Vol 9 (6) ◽  
pp. 1116
Author(s):  
Laurens Maertens ◽  
Pauline Cherry ◽  
Françoise Tilquin ◽  
Rob Van Houdt ◽  
Jean-Yves Matroule
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Stress Responses ◽  
Caulobacter Crescentus ◽  
Oxidative Stress Response ◽  
Transport Systems ◽  
Transcriptomic Response ◽  
Swarmer Cell ◽  
Cu Stress ◽  
Cellular Environment

Bacteria encounter elevated copper (Cu) concentrations in multiple environments, varying from mining wastes to antimicrobial applications of copper. As the role of the environment in the bacterial response to Cu ion exposure remains elusive, we used a tagRNA-seq approach to elucidate the disparate responses of two morphotypes of Caulobacter crescentus NA1000 to moderate Cu stress in a complex rich (PYE) medium and a defined poor (M2G) medium. The transcriptome was more responsive in M2G, where we observed an extensive oxidative stress response and reconfiguration of the proteome, as well as the induction of metal resistance clusters. In PYE, little evidence was found for an oxidative stress response, but several transport systems were differentially expressed, and an increased need for histidine was apparent. These results show that the Cu stress response is strongly dependent on the cellular environment. In addition, induction of the extracytoplasmic function sigma factor SigF and its regulon was shared by the Cu stress responses in both media, and its central role was confirmed by the phenotypic screening of a sigF::Tn5 mutant. In both media, stalked cells were more responsive to Cu stress than swarmer cells, and a stronger basal expression of several cell protection systems was noted, indicating that the swarmer cell is inherently more Cu resistant. Our approach also allowed for detecting several new transcription start sites, putatively indicating small regulatory RNAs, and additional levels of Cu-responsive regulation.

scholarly journals CAU-1, a Subclass B3 Metallo-β-Lactamase of Low Substrate Affinity Encoded by an Ortholog Present in the Caulobacter crescentus Chromosome

2002 ◽  
Vol 46 (6) ◽  
pp. 1823-1830 ◽  
Author(s):  
Jean-Denis Docquier ◽  
Fabrizio Pantanella ◽  
Francesco Giuliani ◽  
Maria Cristina Thaller ◽  
Gianfranco Amicosante ◽  
...  
Keyword(s):  
Caulobacter Crescentus ◽  
Hypothetical Protein ◽  
Exchange Chromatography ◽  
Substrate Affinity ◽  
Gene Encoding ◽  
Native Form ◽  
Significant Similarity ◽  
Expression Studies ◽  
Genes Encoding ◽  
Isoelectric Ph

ABSTRACT The sequenced chromosome of Caulobacter crescentus CB15 encodes a hypothetical protein that exhibits significant similarity (30 to 35% identical residues) to metallo-β-lactamases of subclass B3. An allelic variant of this gene (divergent by 3% of its nucleotides) was cloned in Escherichia coli from C. crescentus type strain DSM4727. Expression studies confirmed the metallo-β-lactamase activity of its product, CAU-1. The enzyme produced in E. coli was purified by two ion-exchange chromatography steps. CAU-1 contains a 29-kDa polypeptide with an alkaline isoelectric pH (>9), and unlike the L1 enzyme of Stenotrophomonas maltophilia, the native form is monomeric. Kinetic analysis revealed a preferential activity toward penicillins, carbapenems, and narrow-spectrum cephalosporins, while oxyimino cephalosporins were poorly or not hydrolyzed. Affinities for the various β-lactams were poor overall (Km values were always >100 μM and often >400 μM). The interaction with divalent ion chelators appeared to occur by a mechanism similar to that prevailing in other members of subclass B3. In C. crescentus, the CAU-1 enzyme is produced independently of β-lactam exposure and, interestingly, the bla CAU determinant is bracketed by three other genes, including two genes encoding enzymes involved in methionine biosynthesis and a gene encoding a putative transcriptional regulator, in an operon-like structure. The CAU-1 enzyme is the first example of a metallo-β-lactamase in a member of the α subdivision of the class Proteobacteria.

Insulin resistance, hypertension and cellular ion transport systems

1992 ◽  
Vol 29 (3-4) ◽  
pp. 196-200 ◽  
Author(s):  
Anna Solini ◽  
Ralph A. DeFronzo
Keyword(s):  
Insulin Resistance ◽  
Ion Transport ◽  
Transport Systems

scholarly journals Association of the Cold Shock DEAD-Box RNA Helicase RhlE to the RNA Degradosome in Caulobacter crescentus

2017 ◽  
Vol 199 (13) ◽  
Author(s):  
Angel A. Aguirre ◽  
Alexandre M. Vicente ◽  
Steven W. Hardwick ◽  
Daniela M. Alvelos ◽  
Ricardo R. Mazzon ◽  
...  
Keyword(s):  
Low Temperature ◽  
Caulobacter Crescentus ◽  
Immunoblot Analysis ◽  
Rna Helicase ◽  
Rnase E ◽  
Rna Helicases ◽  
Content Type ◽  
Dead Box ◽  
Rna Degradosome ◽  
The Dead

ABSTRACT In diverse bacterial lineages, multienzyme assemblies have evolved that are central elements of RNA metabolism and RNA-mediated regulation. The aquatic Gram-negative bacterium Caulobacter crescentus, which has been a model system for studying the bacterial cell cycle, has an RNA degradosome assembly that is formed by the endoribonuclease RNase E and includes the DEAD-box RNA helicase RhlB. Immunoprecipitations of extracts from cells expressing an epitope-tagged RNase E reveal that RhlE, another member of the DEAD-box helicase family, associates with the degradosome at temperatures below those optimum for growth. Phenotype analyses of rhlE, rhlB, and rhlE rhlB mutant strains show that RhlE is important for cell fitness at low temperature and its role may not be substituted by RhlB. Transcriptional and translational fusions of rhlE to the lacZ reporter gene and immunoblot analysis of an epitope-tagged RhlE indicate that its expression is induced upon temperature decrease, mainly through posttranscriptional regulation. RNase E pulldown assays show that other proteins, including the transcription termination factor Rho, a second DEAD-box RNA helicase, and ribosomal protein S1, also associate with the degradosome at low temperature. The results suggest that the RNA degradosome assembly can be remodeled with environmental change to alter its repertoire of helicases and other accessory proteins. IMPORTANCE DEAD-box RNA helicases are often present in the RNA degradosome complex, helping unwind secondary structures to facilitate degradation. Caulobacter crescentus is an interesting organism to investigate degradosome remodeling with change in temperature, because it thrives in freshwater bodies and withstands low temperature. In this study, we show that at low temperature, the cold-induced DEAD-box RNA helicase RhlE is recruited to the RNA degradosome, along with other helicases and the Rho protein. RhlE is essential for bacterial fitness at low temperature, and its function may not be complemented by RhlB, although RhlE is able to complement for rhlB loss. These results suggest that RhlE has a specific role in the degradosome at low temperature, potentially improving adaptation to this condition.

scholarly journals Heterochromatin in Triton

1942 ◽  
Vol 130 (860) ◽  
pp. 324-335 ◽  
Keyword(s):  
Nucleic Acid ◽  
Low Temperature ◽  
Crossing Over

When subjected to low temperature, certain segments of the chromosomes of Triton vulgaris , T. palmatus and T. cristatus are heterochromatic. At mitosis these segments are undercharged and at meiosis uncharged with nucleic acid. These segments show the same type of allocyclic behaviour as do similar segments in Paris , Trillium and Fritillaria . They form Feulgen-positive chromocentres in all diffuse nuclei except pachytene, which is diffuse in Triton . The availability of nucleic acid at the stage when the chromosomes normally spiralize is now shown to be a condition of that spiralization. The diffuse pachytene without chromocentres is followed by meiosis with unspiralized heterochromatin: the diffuse resting nucleus with chromocentres is followed by mitosis with spiralized heterochromatin. With certain exceptions heterochromatin seems to be confined to those parts of chromosomes where chiasmata and crossing-over rarely occur.

Responses of trout gill ion transport systems to acute acidosis

1976 ◽  
Vol 64 (2) ◽  
pp. 511-515
Author(s):  
T. H. Kerstetter ◽  
R. Mize
Keyword(s):  
Lactic Acid ◽  
Rainbow Trout ◽  
Ion Transport ◽  
Ion Uptake ◽  
Transport Systems ◽  
Ph Changes ◽  
Blood Ph ◽  
Slow Infusion ◽  
Trout Gill

The response of rainbow trout Na+ and Cl- uptake systems to acute acidosis was tested by slow infusion of lactic acid into anaesthetized animals. Depression of blood pH by 0–4 pH unit had no effect on influx rates for either ion, and we conclude that gill ion uptake systems do not respond rapidly to blood pH changes.

Sign in / Sign up

Export Citation Format

Share Document