scholarly journals Contribution of the Cell Wall Component Teichuronopeptide to pH Homeostasis and Alkaliphily in the Alkaliphile Bacillus lentus C-125

1999 ◽  
Vol 181 (21) ◽  
pp. 6600-6606 ◽  
Author(s):  
Rikizo Aono ◽  
Masahiro Ito ◽  
Takayoshi Machida
Keyword(s):  
Cell Wall ◽  
Amino Acid Residues ◽  
Alkaline Ph ◽  
Structural Components ◽  
Chromosomal Dna ◽  
Ph Homeostasis ◽  
Cell Wall Component ◽  
Bacillus Lentus ◽  
Defective Mutant ◽  
Alkaline Conditions

ABSTRACT A teichuronopeptide (TUP) is one of major structural components of the cell wall of the facultative alkaliphilic strain Bacillus lentus C-125. A mutant defective in TUP synthesis grows slowly at alkaline pH. An upper limit of pH for growth of the mutant was 10.4, while that of the parental strain C-125 was 10.8. GenetupA, directing synthesis of TUP, was cloned from C-125 chromosomal DNA. The primary translation product of this gene is likely a cytoplasmic protein (57.3 kDa) consisting of 489 amino acid residues. Introduction of the tupA gene into the TUP-defective mutant complemented the mutation responsible for the pleiotropic phenotypes of the mutant, leading to simultaneous disappearance of the defect in TUP synthesis, the diminished ability for cytoplasmic pH homeostasis, and the low tolerance for alkaline conditions. These results demonstrate that the acidic polymer TUP in the cell wall plays a role in pH homeostasis in this alkaliphile.

scholarly journals TheBeauveria bassianaGas3 β-Glucanosyltransferase Contributes to Fungal Adaptation to Extreme Alkaline Conditions

2018 ◽  
Vol 84 (15) ◽  
Author(s):  
Zhibing Luo ◽  
Tongbing Zhang ◽  
Pengfei Liu ◽  
Yuting Bai ◽  
Qiyan Chen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Pathogenic Fungus ◽  
Growth Conditions ◽  
Alkaline Ph ◽  
Ph Responsive ◽  
Content Type ◽  
Cell Wall Remodeling ◽  
Alkaline Conditions ◽  
Increased Sensitivity ◽  
Ph Dependent

ABSTRACTFungal β-1,3-glucanosyltransferases are cell wall-remodeling enzymes implicated in stress response, cell wall integrity, and virulence, with most fungal genomes containing multiple members. The insect-pathogenic fungusBeauveria bassianadisplays robust growth over a wide pH range (pH 4 to 10). A random insertion mutant library screening for increased sensitivity to alkaline (pH 10) growth conditions resulted in the identification and mapping of a mutant to a β-1,3-glucanosyltransferase gene (Bbgas3).Bbgas3expression was pH dependent and regulated by the PacC transcription factor, which activates genes in response to neutral/alkaline growth conditions. Targeted gene knockout ofBbgas3resulted in reduced growth under alkaline conditions, with only minor effects of increased sensitivity to cell wall stress (Congo red and calcofluor white) and no significant effects on fungal sensitivity to oxidative or osmotic stress. The cell walls of ΔBbgas3aerial conidia were thinner than those of the wild-type and complemented strains in response to alkaline conditions, and β-1,3-glucan antibody and lectin staining revealed alterations in cell surface carbohydrate epitopes. The ΔBbgas3mutant displayed alterations in cell wall chitin and carbohydrate content in response to alkaline pH. Insect bioassays revealed impaired virulence for the ΔBbgas3mutant depending upon the pH of the media on which the conidia were grown and harvested. Unexpectedly, a decreased median lethal time to kill (LT50, i.e., increased virulence) was seen for the mutant using intrahemocoel injection assays using conidia grown at acidic pH (5.6). These data show that BbGas3 acts as a pH-responsive cell wall-remodeling enzyme involved in resistance to extreme pH (>9).IMPORTANCELittle is known about adaptations required for growth at high (>9) pH. Here, we show that a specific fungal membrane-remodeling β-1,3-glucanosyltransferase gene (Bbgas3) regulated by the pH-responsive PacC transcription factor forms a critical aspect of the ability of the insect-pathogenic fungusBeauveria bassianato grow at extreme pH. The loss ofBbgas3resulted in a unique decreased ability to grow at high pH, with little to no effects seen with respect to other stress conditions, i.e., cell wall integrity and osmotic and oxidative stress. However, pH-dependent alternations in cell wall properties and virulence were noted for the ΔBbgas3 mutant. These data provide a mechanistic insight into the importance of the specific cell wall structure required to stabilize the cell at high pH and link it to the PacC/Pal/Rim pH-sensing and regulatory system.

scholarly journals Escherichia coli YqjA, a Member of the Conserved DedA/Tvp38 Membrane Protein Family, Is a Putative Osmosensing Transporter Required for Growth at Alkaline pH

2015 ◽  
Vol 197 (14) ◽  
pp. 2292-2300 ◽  
Author(s):  
Sujeet Kumar ◽  
William T. Doerrler
Keyword(s):  
Escherichia Coli ◽  
Membrane Protein ◽  
Amino Acid Identity ◽  
Protein Family ◽  
Cytoplasmic Ph ◽  
Alkaline Ph ◽  
Ph Homeostasis ◽  
Content Type ◽  
E Coli ◽  
Alkaline Conditions

ABSTRACTThe ability to persist and grow under alkaline conditions is an important characteristic of many bacteria. In order to survive at alkaline pH,Escherichia colimust maintain a stable cytoplasmic pH of about 7.6. Membrane cation/proton antiporters play a major role in alkaline pH homeostasis by catalyzing active inward proton transport. The DedA/Tvp38 family is a highly conserved membrane protein family of unknown function present in most sequenced genomes. YqjA and YghB are members of theE. coliDedA family with 62% amino acid identity and partially redundant functions. We have shown thatE. coliwith ΔyqjAand ΔyghBmutations cannot properly maintain the proton motive force (PMF) and is compromised in PMF-dependent drug efflux and other PMF-dependent functions. Furthermore, the functions of YqjA and YghB are dependent upon membrane-embedded acidic amino acids, a hallmark of several families of proton-dependent transporters. Here, we show that the ΔyqjAmutant (but not ΔyghB) cannot grow under alkaline conditions (ranging from pH 8.5 to 9.5), unlike the parentE. coli. Overexpression ofyqjArestores growth at alkaline pH, but only when more than ∼100 mM sodium or potassium is present in the growth medium. Increasing the osmotic pressure by the addition of sucrose enhances the ability of YqjA to support growth under alkaline conditions in the presence of low salt concentrations, consistent with YqjA functioning as an osmosensor. We suggest that YqjA possesses proton-dependent transport activity that is stimulated by osmolarity and that it plays a significant role in the survival ofE. coliat alkaline pH.IMPORTANCEThe ability to survive under alkaline conditions is important for many species of bacteria.Escherichia colican grow at pH 5.5 to 9.5 while maintaining a constant cytoplasmic pH of about 7.6. Under alkaline conditions, bacteria rely upon proton-dependent transporters to maintain a constant cytoplasmic pH. The DedA/Tvp38 protein family is a highly conserved but poorly characterized family of membrane proteins. Here, we show that the DedA/Tvp38 protein YqjA is critical forE. colito survive at pH 8.5 to 9.5. YqjA requires sodium and potassium for this function. At low cation concentrations, osmolytes, including sucrose, can facilitate rescue ofE. coligrowth by YqjA at high pH. These data are consistent with YqjA functioning as an osmosensing cation-dependent proton transporter.

scholarly journals The Lysine 299 Residue Endows the Multisubunit Mrp1 Antiporter with Dominant Roles in Na+Resistance and pH Homeostasis inCorynebacterium glutamicum

2018 ◽  
Vol 84 (10) ◽  
Author(s):  
Ning Xu ◽  
Yingying Zheng ◽  
Xiaochen Wang ◽  
Terry A. Krulwich ◽  
Yanhe Ma ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Expression Patterns ◽  
Alkaline Stress ◽  
Alkaline Ph ◽  
Ph Homeostasis ◽  
Conserved Residues ◽  
Content Type ◽  
Ion Translocation ◽  
Alkaline Tolerance ◽  
Alkaline Conditions

ABSTRACTCorynebacterium glutamicumis generally regarded as a moderately salt- and alkali-tolerant industrial organism. However, relatively little is known about the molecular mechanisms underlying these specific adaptations. Here, we found that the Mrp1 antiporter played crucial roles in conferring both environmental Na+resistance and alkali tolerance whereas the Mrp2 antiporter was necessary in coping with high-KCl stress at alkaline pH. Furthermore, the Δmrp1Δmrp2double mutant showed the most-severe growth retardation and failed to grow under high-salt or alkaline conditions. Consistent with growth properties, the Na+/H+antiporters ofC. glutamicumwere differentially expressed in response to specific salt or alkaline stress, and an alkaline stimulus particularly induced transcript levels of the Mrp-type antiporters. When the major Mrp1 antiporter was overwhelmed,C. glutamicummight employ alternative coordinate strategies to regulate antiport activities. Site-directed mutagenesis demonstrated that several conserved residues were required for optimal Na+resistance, such as Mrp1A K299, Mrp1C I76, Mrp1A H230, and Mrp1D E136. Moreover, the chromosomal replacement of lysine 299 in the Mrp1A subunit resulted in a higher intracellular Na+level and a more alkaline intracellular pH value, thereby causing a remarkable growth attenuation. Homology modeling of the Mrp1 subcomplex suggested two possible ion translocation pathways, and lysine 299 might exert its effect by affecting the stability and flexibility of the cytoplasm-facing channel in the Mrp1A subunit. Overall, these findings will provide new clues to the understanding of salt-alkali adaptation duringC. glutamicumstress acclimatization.IMPORTANCEThe capacity to adapt to harsh environments is crucial for bacterial survival and product yields, including industrially usefulCorynebacterium glutamicum. AlthoughC. glutamicumexhibits a marked resistance to salt-alkaline stress, the possible mechanism for these adaptations is still unclear. Here, we present the physiological functions and expression patterns ofC. glutamicumputative Na+/H+antiporters and conserved residues of Mrp1 subunits, which respond to different salt and alkaline stresses. We found that the Mrp-type antiporters, particularly the Mrp1 antiporter, played a predominant role in maintaining intracellular nontoxic Na+levels and alkaline pH homeostasis. Loss of the major Mrp1 antiporter had a profound effect on gene expression of other antiporters under salt or alkaline conditions. The lysine 299 residue may play its essential roles in conferring salt and alkaline tolerance by affecting the ion translocation channel of the Mrp1A subunit. These findings will contribute to a better understanding of Na+/H+antiporters in sodium antiport and pH regulation.

Molecular Structure of the Outermost Cell Wall Component of Spirillum Serpens

1977 ◽  
Vol 35 ◽  
pp. 342-343
Author(s):  
Wah Chiu ◽  
David Grano
Keyword(s):  
Molecular Structure ◽  
Cell Wall ◽  
Outer Membrane ◽  
Gel Electrophoresis ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Cell Wall Component ◽  
Protein Components ◽  
Exposure Technique ◽  
Structural Aspects

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.

scholarly journals A Study of Catechin Photostability Using Photolytic Processing

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 293
Author(s):  
Jeu-Ming P. Yuann ◽  
Shwu-Yuan Lee ◽  
Meei-Ju Yang ◽  
Shiuh-Tsuen Huang ◽  
Chien-Wei Cheng ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Superoxide Anion ◽  
Anion Radical ◽  
Alkaline Solutions ◽  
Light Illumination ◽  
Drug Resistant ◽  
Alkaline Ph ◽  
Radical Species ◽  
Alkaline Conditions ◽  
Photolytic Reaction

Catechin exhibits numerous physiological characteristics. In this study, we determined the photosensitivity of catechin to various lights under alkaline conditions, and the mechanisms by which catechin generates free radical species and polymerizes via a photoreaction. In addition to this, the application of catechin photolysis was investigated. A solution of catechin is transparent, but turns yellowish under blue light illumination (BLI) in neutral or weak alkaline solutions. When catechin is subjected to BLI, a dimeric catechin (proanthocyanidin) and a superoxide anion radical (O2•−) are generated in a photolytic reaction. When ascorbic acid or gallic acid is added to catechin and the mixture is subjected to BLI at alkaline pH, fewer catechin dimers and less O2•− are produced, because both acids inhibit the photosensitive oxidation of catechin. When AlCl3 is added to catechin and the mixture is subjected to BLI at pH 8, a photolytic reaction is suppressed by AlCl3, and AlCl3 acts as a catalyst for the disconnection of proanthocyanidin during photolysis. Under alkaline conditions, catechin generates O2•− via photosensitive oxidation, which suppresses the growth of Acinetobacter baumannii (A. baumannii) by at least 4 logs, and deactivates its multi-drug-resistant strain. This study shows that catechin photolysis is a process of oxidation, and that it can be safely applied as a tool for environmental applications.

Kinetic study on the liquefaction of wood and its three cell wall component in polyhydric alcohols

2014 ◽  
Vol 113 ◽  
pp. 1596-1600 ◽  
Author(s):  
Hairong Zhang ◽  
Huijuan Yang ◽  
Haijun Guo ◽  
Chao Huang ◽  
Lian Xiong ◽  
...  
Keyword(s):  
Cell Wall ◽  
Kinetic Study ◽  
Cell Wall Component ◽  
Polyhydric Alcohols

scholarly journals CpxP, a Stress-Combative Member of the Cpx Regulon

1998 ◽  
Vol 180 (4) ◽  
pp. 831-839 ◽  
Author(s):  
Paul N. Danese ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Envelope Protein ◽  
Periplasmic Protein ◽  
Dependent Manner ◽  
Alkaline Ph ◽  
Signal Transduction System ◽  
Two Component ◽  
Mutant Strains ◽  
Alkaline Conditions ◽  
Two Component Signal Transduction

ABSTRACT The CpxA/R two-component signal transduction system ofEscherichia coli can combat a variety of extracytoplasmic protein-mediated toxicities. The Cpx system performs this function, in part, by increasing the synthesis of the periplasmic protease, DegP. However, other factors are also employed by the Cpx system for this stress-combative function. In an effort to identify these remaining factors, we screened a collection of random lacZ operon fusions for those fusions whose transcription is regulated by CpxA/R. Through this approach, we have identified a new locus,cpxP, whose transcription is stimulated by activation of the Cpx pathway. cpxP specifies a periplasmic protein that can combat the lethal phenotype associated with the synthesis of a toxic envelope protein. In addition, we show that cpxPtranscription is strongly induced by alkaline pH in a CpxA-dependent manner and that cpxP and cpx mutant strains display hypersensitivity to growth in alkaline conditions.

Sign in / Sign up

Export Citation Format

Share Document