scholarly journals Carbon Source Dependence and Photostimulation of Conidiation in Hypocrea atroviridis

2007 ◽  
Vol 74 (1) ◽  
pp. 245-250 ◽  
Author(s):  
Martina A. Friedl ◽  
Christian P. Kubicek ◽  
Irina S. Druzhinina
Keyword(s):  
Carbon Source ◽  
Cyclic Amp ◽  
Parental Strain ◽  
Carbon Sources ◽  
Spore Formation ◽  
Blue Light Receptor ◽  
Small Set ◽  
Prime Determinant ◽  
Catalytic Role

ABSTRACT Hypocrea atroviridis is frequently used as a photomorphogenetic model due to its ability to conidiate upon exposure to light. Light is thereby believed to be the primary trigger for spore formation. In contrast, we show here that conidiation is primarily carbon source dependent and that illumination plays a catalytic role; of a total of 95 tested carbon sources, only a small set of carbohydrates, polyols, and sugar acids allowed conidiation in darkness, and on most of them, conidiation was significantly more strongly expressed in light. In addition, there are also a number of carbon sources on which H. atroviridis conidiates in darkness, but light does not further stimulate the process. Yet on another small set of carbon sources (l-sorbitol, d-fucose, d- and l-arabinose, and erythritol), H. atroviridis shows better sporulation in darkness than in light. No sporulation was observed on organic acids and amino acids. Mutants with deletions in the two blue-light receptor proteins BLR-1 and BLR-2 generally showed weaker conidiation on a smaller number of carbon sources than did the parental strain, yet they clearly sporulated on 15 and 27 of the 95 carbon sources tested, respectively. Of the carbon sources supporting sporulation, only 11 supported the conidiation of both mutants, suggesting that the BLR-1 and BLR-2 receptors are variously involved in the carbon source-dependent regulation of spore formation. The addition of cyclic AMP, which has been reported to lead to conidiation in darkness, both positively and negatively affected sporulation and resulted in different effects in the parental strain and the two Δblr mutants. Our data show that the carbon source is the prime determinant for conidiation and that it influences the organism's regulation of conidiation by means of BLR-1 and BLR-2 and their cross talk with cyclic AMP.

scholarly journals The Cyclic AMP Receptor Protein Regulates Quorum Sensing and Global Gene Expression in Yersinia pestis during Planktonic Growth and Growth in Biofilms

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Jeremy T. Ritzert ◽  
George Minasov ◽  
Ryan Embry ◽  
Matthew J. Schipma ◽  
Karla J. F. Satchell
Keyword(s):  
Gene Expression ◽  
Quorum Sensing ◽  
Carbon Source ◽  
Cyclic Amp ◽  
Yersinia Pestis ◽  
Carbon Sources ◽  
Transcriptional Regulator ◽  
Receptor Protein ◽  
Content Type ◽  
Bacterial Physiology

ABSTRACT Cyclic AMP (cAMP) receptor protein (Crp) is an important transcriptional regulator of Yersinia pestis. Expression of crp increases during pneumonic plague as the pathogen depletes glucose and forms large biofilms within lungs. To better understand control of Y. pestis Crp, we determined a 1.8-Å crystal structure of the protein-cAMP complex. We found that compared to Escherichia coli Crp, C helix amino acid substitutions in Y. pestis Crp did not impact the cAMP dependency of Crp to bind DNA promoters. To investigate Y. pestis Crp-regulated genes during plague pneumonia, we performed RNA sequencing on both wild-type and Δcrp mutant bacteria growing in planktonic and biofilm states in minimal media with glucose or glycerol. Y. pestis Crp was found to dramatically alter expression of hundreds of genes in a manner dependent upon carbon source and growth state. Gel shift assays confirmed direct regulation of the malT and ptsG promoters, and Crp was then linked to Y. pestis growth on maltose as a sole carbon source. Iron regulation genes ybtA and fyuA were found to be indirectly regulated by Crp. A new connection between carbon source and quorum sensing was revealed as Crp was found to regulate production of acyl-homoserine lactones (AHLs) through direct and indirect regulation of genes for AHL synthetases and receptors. AHLs were subsequently identified in the lungs of Y. pestis-infected mice when crp expression was highest in Y. pestis biofilms. Thus, in addition to the well-studied pla gene, other Crp-regulated genes likely have important functions during plague infection. IMPORTANCE Bacterial pathogens have evolved extensive signaling pathways to translate environmental signals into changes in gene expression. While Crp has long been appreciated for its role in regulating metabolism of carbon sources in many bacterial species, transcriptional profiling has revealed that this protein regulates many other aspects of bacterial physiology. The plague pathogen Y. pestis requires this global regulator to survive in blood, skin, and lungs. During disease progression, this organism adapts to changes within these niches. In addition to regulating genes for metabolism of nonglucose sugars, we found that Crp regulates genes for virulence, metal acquisition, and quorum sensing by direct or indirect mechanisms. Thus, this single transcriptional regulator, which responds to changes in available carbon sources, can regulate multiple critical behaviors for causing disease.

scholarly journals The Catabolite Repressor/Activator Cra Is a Bridge Connecting Carbon Metabolism and Host Colonization in the Plant Drought Resistance-Promoting Bacterium Pantoea alhagi LTYR-11Z

2018 ◽  
Vol 84 (13) ◽  
Author(s):  
Lei Zhang ◽  
Muhang Li ◽  
Qiqi Li ◽  
Chaoqiong Chen ◽  
Meng Qu ◽  
...  
Keyword(s):  
Carbon Source ◽  
Carbon Metabolism ◽  
Carbon Sources ◽  
Endophytic Bacterium ◽  
Bacterial Attachment ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Host Colonization ◽  
Content Type

ABSTRACT Efficient root colonization is a prerequisite for application of plant growth-promoting (PGP) bacteria in improving health and yield of agricultural crops. We have recently identified an endophytic bacterium, Pantoea alhagi LTYR-11Z, with multiple PGP properties that effectively colonizes the root system of wheat and improves its growth and drought tolerance. To identify novel regulatory genes required for wheat colonization, we screened an LTYR-11Z transposon (Tn) insertion library and found cra to be a colonization-related gene. By using transcriptome (RNA-seq) analysis, we found that transcriptional levels of an eps operon, the ydiV gene encoding an anti-FlhD 4 C 2 factor, and the yedQ gene encoding an enzyme for synthesis of cyclic dimeric GMP (c-di-GMP) were significantly downregulated in the Δ cra mutant. Further studies demonstrated that Cra directly binds to the promoters of the eps operon, ydiV , and yedQ and activates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production and biofilm formation. Consistent with previous findings that Cra plays a role in transcriptional regulation in response to carbon source availability, the activating effects of Cra were much more pronounced when LTYR-11Z was grown within a gluconeogenic environment than when it was grown within a glycolytic environment. We further demonstrate that the ability of LTYR-11Z to colonize wheat roots is modulated by the availability of carbon sources. Altogether, these results uncover a novel strategy utilized by LTYR-11Z to achieve host colonization in response to carbon nutrition in the environment, in which Cra bridges a connection between carbon metabolism and colonization capacity of LTYR-11Z. IMPORTANCE Rapid and appropriate response to environmental signals is crucial for bacteria to adapt to competitive environments and to establish interactions with their hosts. Efficient colonization and persistence within the host are controlled by various regulatory factors that respond to specific environmental cues. The most common is nutrient availability. In this work, we unraveled the pivotal role of Cra in regulation of colonization ability of Pantoea alhagi LTYR-11Z in response to carbon source availability. Moreover, we identified three novel members of the Cra regulon involved in EPS synthesis, regulation of flagellar biosynthesis, and synthesis of c-di-GMP and propose a working model to explain the Cra-mediated regulatory mechanism that links carbon metabolism to host colonization. This study elucidates the regulatory role of Cra in bacterial attachment and colonization of plants, which raises the possibility of extending our studies to other bacteria associated with plant and human health.

The role of cyclic GMP in regulating myosin during chemotaxis of Dictyostelium: evidence from a mutant lacking the normal cyclic GMP response to cyclic AMP

1993 ◽  
Vol 106 (2) ◽  
pp. 591-595 ◽  
Author(s):  
G. Liu ◽  
H. Kuwayama ◽  
S. Ishida ◽  
P.C. Newell
Keyword(s):  
Cyclic Amp ◽  
Heavy Chain ◽  
Cyclic Gmp ◽  
Parental Strain ◽  
Response Curve ◽  
Myosin Ii ◽  
Cellular Slime ◽  
Mutant Cells ◽  
Slight Displacement

Evidence has previously been reported that, during chemotaxis of the cellular slime mould Dictyostelium discoideum, cyclic GMP regulates the association of myosin II with the cytoskeleton and that this regulation is effected by inhibiting myosin II heavy chain phosphorylation (Liu and Newell, J. Cell Sci., 90, 123–129, 1988; 98, 483–490, 1991). Here we provide further evidence in support of this hypothesis using a mutant (KI-10) that is defective in chemotaxis and lacks the normal cyclic AMP-induced cyclic GMP response. We found that the cyclic AMP-induced cytoskeletal actin response was similar to that of the parental strain in this mutant (although showing a slight displacement in the dose-response curve) but the cytoskeletal myosin II heavy chain response was abolished. Moreover, the mutant showed no phosphorylation of myosin II heavy chain in response to cyclic AMP. Compared to the parental strain XP55, the mutant cells contained approximately 40% more protein and their doubling time was 30% longer. These differences could be due to differences in the efficiency of cell division, a process in which the proper regulation of myosin function is essential and in which cyclic GMP may therefore play a role.

scholarly journals In Vivo Analysis of HPr Reveals a Fructose-Specific Phosphotransferase System That Confers High-Affinity Uptake in Streptomyces coelicolor

2003 ◽  
Vol 185 (3) ◽  
pp. 929-937 ◽  
Author(s):  
Harald Nothaft ◽  
Stephan Parche ◽  
Annette Kamionka ◽  
Fritz Titgemeyer
Keyword(s):  
Carbon Source ◽  
Glucose Repression ◽  
Streptomyces Coelicolor ◽  
Carbon Sources ◽  
Glycerol Kinase ◽  
Transcriptional Analysis ◽  
Phosphotransferase System ◽  
Gram Positive ◽  
High Affinity

ABSTRACT HPr, the histidine-containing phosphocarrier protein of the bacterial phosphotransferase system (PTS), serves multiple functions in carbohydrate uptake and carbon source regulation in low-G+C-content gram-positive bacteria and in gram-negative bacteria. To assess the role of HPr in the high-G+C-content gram-positive organism Streptomyces coelicolor, the encoding gene, ptsH, was deleted. The ptsH mutant BAP1 was impaired in fructose utilization, while growth on other carbon sources was not affected. Uptake assays revealed that BAP1 could not transport appreciable amounts of fructose, while the wild type showed inducible high-affinity fructose transport with an apparent Km of 2 μM. Complementation and reconstitution experiments demonstrated that HPr is indispensable for a fructose-specific PTS activity. Investigation of the putative fruKA gene locus led to identification of the fructose-specific enzyme II permease encoded by the fruA gene. Synthesis of HPr was not specifically enhanced in fructose-grown cells and occurred also in the presence of non-PTS carbon sources. Transcriptional analysis of ptsH revealed two promoters that are carbon source regulated. In contrast to what happens in other bacteria, glucose repression of glycerol kinase was still operative in a ptsH background, which suggests that HPr is not involved in general carbon regulation. However, fructose repression of glycerol kinase was lost in BAP1, indicating that the fructose-PTS is required for transduction of the signal. This study provides the first molecular genetic evidence of a physiological role of the PTS in S. coelicolor.

scholarly journals Carbon Source-Dependent Phosphorylation of Hexokinase PII and Its Role in the Glucose-Signaling Response in Yeast

1998 ◽  
Vol 18 (5) ◽  
pp. 2940-2948 ◽  
Author(s):  
Francisca Randez-Gil ◽  
Pascual Sanz ◽  
Karl-Dieter Entian ◽  
Jose Antonio Prieto
Keyword(s):  
Carbon Source ◽  
Glucose Repression ◽  
Carbon Sources ◽  
Glucose Signaling ◽  
Regulatory Effects ◽  
Metabolic Signal ◽  
Signal Transductions ◽  
Mutant Cells

ABSTRACT The HXK2 gene is required for a variety of regulatory effects leading to an adaptation for fermentative metabolism inSaccharomyces cerevisiae. However, the molecular basis of the specific role of Hxk2p in these effects is still unclear. One important feature in order to understand the physiological function of hexokinase PII is that it is a phosphoprotein, since protein phosphorylation is essential in most metabolic signal transductions in eukaryotic cells. Here we show that Hxk2p exists in vivo in a dimeric-monomeric equilibrium which is affected by phosphorylation. Only the monomeric form appears phosphorylated, whereas the dimer does not. The reversible phosphorylation of Hxk2p is carbon source dependent, being more extensive on poor carbon sources such as galactose, raffinose, and ethanol. In vivo dephosphorylation of Hxk2p is promoted after addition of glucose. This effect is absent in glucose repression mutants cat80/grr1, hex2/reg1, andcid1/glc7. Treatment of a glucose crude extract fromcid1-226 (glc7-T152K) mutant cells with λ-phosphatase drastically reduces the presence of phosphoprotein, suggesting that CID1/GLC7 phosphatase together with its regulatory HEX2/REG1 subunit are involved in the dephosphorylation of the Hxk2p monomer. An HXK2 mutation encoding a serine-to-alanine change at position 15 [HXK2(S15A)] was to clarify the in vivo function of the phosphorylation of hexokinase PII. In this mutant, where the Hxk2 protein is unable to undergo phosphorylation, the cells could not provide glucose repression of invertase. Glucose induction ofHXT gene expression is also affected in cells expressing the mutated enzyme. Although we cannot rule out a defect in the metabolic state of the cell as the origin of these phenomena, our results suggest that the phosphorylation of hexokinase is essential in vivo for glucose signal transduction.

scholarly journals Role of Intracellular Polysaccharide in Persistence of Streptococcus mutans

2009 ◽  
Vol 191 (23) ◽  
pp. 7315-7322 ◽  
Author(s):  
Monica Busuioc ◽  
Katarzyna Mackiewicz ◽  
Bettina A. Buttaro ◽  
Patrick J. Piggot
Keyword(s):  
Carbon Source ◽  
Streptococcus Mutans ◽  
Batch Culture ◽  
Parental Strain ◽  
Glycogen Synthase ◽  
Glucose Starvation ◽  
Intracellular Polysaccharide ◽  
Excess Glucose

ABSTRACT Intracellular polysaccharide (IPS) is accumulated by Streptococcus mutans when the bacteria are grown in excess sugar and can contribute toward the cariogenicity of S. mutans. Here we show that inactivation of the glgA gene (SMU1536), encoding a putative glycogen synthase, prevented accumulation of IPS. IPS is important for the persistence of S. mutans grown in batch culture with excess glucose and then starved of glucose. The IPS was largely used up within 1 day of glucose starvation, and yet survival of the parental strain was extended by at least 15 days beyond that of a glgA mutant; potentially, some feature of IPS metabolism distinct from providing nutrients is important for persistence. IPS was not needed for persistence when sucrose was the carbon source or when mucin was present.

scholarly journals Key Role of Ser562/661 in Snf1-Dependent Regulation of Cat8p in Saccharomyces cerevisiae and Kluyveromyces lactis

2004 ◽  
Vol 24 (10) ◽  
pp. 4083-4091 ◽  
Author(s):  
Godefroid Charbon ◽  
Karin D. Breunig ◽  
Ruddy Wattiez ◽  
Jean Vandenhaute ◽  
Isabelle Noël-Georis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Target Genes ◽  
Kluyveromyces Lactis ◽  
Active Form ◽  
Phosphorylation Site ◽  
Carbon Sources ◽  
Mutant Form ◽  
Zinc Cluster

ABSTRACT Utilization of nonfermentable carbon sources by Kluyveromyces lactis and Saccharomyces cerevisiae requires the Snf1p kinase and the Cat8p transcriptional activator, which binds to carbon source-responsive elements of target genes. We demonstrate that KlSnf1p and KlCat8p from K. lactis interact in a two-hybrid system and that the interaction is stronger with a kinase-dead mutant form of KlSnf1p. Of two putative phosphorylation sites in the KlCat8p sequence, serine 661 was identified as a key residue governing KlCat8p regulation. Serine 661 is located in the middle homology region, a regulatory domain conserved among zinc cluster transcription factors, and is part of an Snf1p consensus phosphorylation site. Single mutations at this site are sufficient to completely change the carbon source regulation of the KlCat8p transactivation activity observed. A serine-to-glutamate mutant form mimicking constitutive phosphorylation results in a nearly constitutively active form of KlCat8p, while a serine-to-alanine mutation has the reverse effect. Furthermore, it is shown that KlCat8p phosphorylation depends on KlSNF1. The Snf1-Cat8 connection is evolutionarily conserved: mutation of corresponding serine 562 of ScCat8p gave similar results in S. cerevisiae. The enhanced capacity of ScCat8S562E to suppress the phenotype caused by snf1 strengthens the hypothesis of direct phosphorylation of Cat8p by Snf1p. Unlike that of S. cerevisiae ScCAT8, KlCAT8 transcription is not carbon source regulated, illustrating the prominent role of posttranscriptional regulation of Cat8p in K. lactis.

scholarly journals Role of gene duplications in the adaptation of Salmonella typhimurium to growth on limiting carbon sources.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 19-28 ◽  
Author(s):  
R V Sonti ◽  
J R Roth
Keyword(s):  
Carbon Source ◽  
Salmonella Typhimurium ◽  
Carbon Sources ◽  
Chromosomal Segment ◽  
Transport Systems ◽  
Energy Sources ◽  
Gene Duplications ◽  
Large Segment

Abstract Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation, growth occurs almost exclusively in the duplication-containing fraction of the population. Cells with duplications of one large segment of the chromosome are repeatedly selected regardless of which of these carbon sources limits growth. The duplicated chromosomal segment encodes the transport systems for all of these carbon sources. This duplication is not selected during growth on a carbon source for which the permease is not included within the duplication segment. This suggests that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source. Inclusion of the permease alone is not sufficient to explain the growth advantage of the duplications, since other common duplications that include the permease are not selected.

Effect of carbon source on Phenobarbital metabolism by Rhizopus stolonifer

2010 ◽  
Vol 3 (2) ◽  
pp. 1022-1027
Author(s):  
Kavitha K ◽  
Asha S ◽  
Hima Bindu T.V.L ◽  
Vidyavathi M
Keyword(s):  
Carbon Source ◽  
High Performance ◽  
Carbon Sources ◽  
In Vitro Models ◽  
Rhizopus Stolonifer ◽  
Safety And Efficacy ◽  
Alternative Systems ◽  
Toxicological Studies ◽  
Microbial Model

The safety and efficacy of a drug is based on its metabolism or metabolite formed. The metabolism of drugs can be studied by different in vitro models, among which microbial model became popular. In the present study, eight microbes were screened for their ability to metabolize phenobarbital in a manner comparable to humans with a model to develop alternative systems to study human drug metabolism. Among the different microbes screened, a filamentous fungi Rhizopus stolonifer metabolized phenobarbital to its metabolite which is used for further pharmacological and toxicological studies. The transformation of phenobarbital was identified by high- performance liquid chromatography (HPLC). Interestingly, Rhizopus stolonifer sample showed an extra metabolite peak at 3.11min. compared to its controls. The influence of different carbon sources in media used for growth of fungus, on metabolite production was studied, to find its effect in production of metabolite as the carbon source may influence the growth of the cell.

Sign in / Sign up

Export Citation Format

Share Document