Cytoskeleton-related structures in tetrahymena thermophila: microfilaments at the apical and division-furrow rings

1981 ◽  
Vol 51 (1) ◽  
pp. 241-253
Author(s):  
M. Jerka-Dziadosz
Keyword(s):  
Cell Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Tetrahymena Thermophila ◽  
Apical Region ◽  
Basal Bodies ◽  
Wild Type ◽  
Fixation Procedure ◽  
Contractile Ring ◽  
Dividing Cells

A ring consisting of microfilaments was found in the apical region of Tetrahymena thermophila wild-type strain B and janus mutant. This ring, about 0.4 micrometer wide and 0.2 micrometer thick, is located at the bases of the anterior, non-ciliated basal bodies of the apical ciliary couplets. The apical ring is made of fine filaments showing a banded pattern, the distance between bands depending on the fixation procedure and ranging from 30–200 nm. The bands are made of small beads fastened to the filaments. The microfilaments of the apical ring are attached to the bases of the basel bodies. No connection with the cell membrane was found. In dividing cells in the incipient furrow region of filamentous band originates from the epiplasmic fibrogranular meshwork. This contractile ring is about 0.4 micrometer wide and 0.8 micrometer thick. It is formed by circumferentially aligned microfibrils. During constriction the contractile ring remains associated with the epiplasmic layer, which in turn adheres to the inner alveolar membrane. The microfilaments of both the apical and the division-furrow rings have diameters ranging from about 3.8-7.I nm.

scholarly journals C-5(6) Sterol Desaturase from Tetrahymena thermophila: Gene Identification and Knockout, Sequence Analysis, and Comparison to Other C-5(6) Sterol Desaturases

2009 ◽  
Vol 8 (8) ◽  
pp. 1287-1297 ◽  
Author(s):  
Alejandro D. Nusblat ◽  
Sebastián R. Najle ◽  
Mariela L. Tomazic ◽  
Antonio D. Uttaro ◽  
Clara B. Nudel
Keyword(s):  
Type Strain ◽  
Deletion Mutant ◽  
Wild Type Strain ◽  
Tetrahymena Thermophila ◽  
Gene Replacement ◽  
Gene Identification ◽  
Wild Type ◽  
Reverse Transcription Pcr ◽  
Gene Coding ◽  
Transmembrane Regions

ABSTRACT The gene coding for a C-5(6) sterol desaturase in Tetrahymena thermophila, DES5A, has been identified by the knockout of the TTHERM_01194720 sequence. Macronucleus transformation was achieved by biolistic bombardment and gene replacement through phenotypic assortment, using paromomycin as the selective agent. A knockout cell line (KO270) showed a phenotype consistent with that of the DES5A deletion mutant. KO270 converted only 6% of the added sterol into the C-5 unsaturated derivative, while the wild type accumulated 10-fold larger amounts under similar conditions. The decreased desaturation activity is specific for the C-5(6) position of lathosterol and cholestanol; other desaturations, namely C-7(8) and C-22(23), were not affected. Analysis by reverse transcription-PCR reveals that DES5A is transcribed both in the presence and absence of cholestanol in wild-type cells, whereas the transcribed gene was not detected in KO270. The growth of KO270 was undistinguishable from that of the wild-type strain. Des5Ap resembles known C-5(6) sterol desaturases, displaying the three typical histidine motifs, four hydrophobic transmembrane regions, and two other highly conserved domains of unknown function. A phylogenetic analysis placed T. thermophila's enzyme and Paramecium orthologues in a cluster together with functionally characterized C-5 sterol desaturases from vertebrates, fungi, and plants, although in a different branch.

scholarly journals Effect of Hook Subunit Concentration on Assembly and Control of Length of the Flagellar Hook ofSalmonella

1999 ◽  
Vol 181 (18) ◽  
pp. 5808-5813 ◽  
Author(s):  
Kazumasa Muramoto ◽  
Shigeru Makishima ◽  
Shin-Ichi Aizawa ◽  
Robert M. Macnab
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Basal Bodies ◽  
Wild Type ◽  
Hook Length ◽  
Capping Protein ◽  
Protein Levels ◽  
Junction Protein ◽  
And Control ◽  
Control Protein

ABSTRACT The flagellar hook of Salmonella is a filamentous polymer made up of subunits of the protein FlgE. Hook assembly is terminated when the length reaches about 55 nm. After our recent study of the effect of cellular levels of the hook length control protein FliK, we have now analyzed the effect of cellular levels of FlgE itself. When FlgE was overproduced in a wild-type strain, afliC (flagellin) mutant, or a fliD(hook-associated protein 2 [HAP2], filament capping protein) mutant, the hooks remained at the wild-type length. In a fliK (hook length control protein) mutant, which produces long hooks (polyhooks), the overproduction of FlgE resulted in extraordinarily long hooks (superpolyhooks). In a flgK (HAP1, first hook-filament junction protein) mutant or a flgL (HAP3, second hook-filament junction protein) mutant, the overproduction of FlgE also resulted in longer than normal hooks. Thus, at elevated hook protein levels not only FliK but also FlgK and FlgL are necessary for the proper termination of hook elongation. When FlgE was severely underproduced, basal bodies without hooks were often observed. However, those hooks that were seen were of wild-type length, demonstrating that FlgE underproduction decreases the probability of the initiation of hook assembly but not the extent of hook elongation.

scholarly journals Novel Toluene Elimination System in a Toluene-Tolerant Microorganism

2000 ◽  
Vol 182 (22) ◽  
pp. 6451-6455 ◽  
Author(s):  
Hideki Kobayashi ◽  
Katsuyuki Uematsu ◽  
Hisako Hirayama ◽  
Koki Horikoshi
Keyword(s):  
Membrane Proteins ◽  
Cell Membrane ◽  
Outer Membrane ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Wild Type ◽  
Sensitive Mutant

ABSTRACT In studies of Pseudomonas putida IH-2000, a toluene-tolerant microorganism, membrane vesicles (MVs) were found to be released from the outer membrane when toluene was added to the culture. These MVs were found to be composed of phospholipids, lipopolysaccharides (LPS), and very low amounts of outer membrane proteins. The MVs also contained a higher concentration of toluene molecules (0.172 ± 0.012 mol/mol of lipid) than that found in the cell membrane. In contrast to the wild-type strain, the toluene-sensitive mutant strain 32, which differs from the parent strain in LPS and outer membrane proteins, did not release MVs from the outer membrane. The toluene molecules adhering to the outer membrane are eliminated by the shedding of MVs, and this system appears to serve as an important part of the toluene tolerance system of IH-2000.

Proportional control of organelle position by a mechanism which similarly monitors cell size of wild type and conical form-mutant Tetrahymena

Development ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 261-274
Author(s):  
Denis H. Lynn
Keyword(s):  
Cell Size ◽  
Tetrahymena Thermophila ◽  
Cell Length ◽  
Basal Bodies ◽  
Wild Type ◽  
Cell Type ◽  
Cell Width ◽  
Dividing Cells ◽  
Conical Form

Distance between mouthparts of dividing cells of wild type and conical form-mutant Tetrahymena thermophila (formerly T. pyriformis syngen 1) is directly proportional to cell size. This distance is related to cell length in both wild type and conical cells although the proportionality is different in each cell type. However, for both wild type and conical cells the distance between mouthparts is directly and similarly proportional to the product of cell length and cell width which is an estimate of cell size. Evidence has been obtained which suggests that the new mouthparts are positioned with reference to the anterior mouthparts rather than to either pole of the cell. Determination of the site of the new mouthparts is not related to the number of basal bodies between the two sets of mouthparts.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Mab_3083c Is a Homologue of RNase J and Plays a Role in Colony Morphotype, Aggregation, and Sliding Motility of Mycobacterium abscessus

2021 ◽  
Vol 9 (4) ◽  
pp. 676
Author(s):  
Ting-Yu Liu ◽  
Sheng-Hui Tsai ◽  
Jenn-Wei Chen ◽  
Yu-Ching Wang ◽  
Shiau-Ting Hu ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Opportunistic Pathogen ◽  
Mycobacterium Abscessus ◽  
Colony Morphology ◽  
Clinical Strain ◽  
Immunocompromised Patients ◽  
Clinical Infection ◽  
Wild Type ◽  
Sliding Motility

Mycobacterium abscessus is an opportunistic pathogen causing human diseases, especially in immunocompromised patients. M. abscessus strains with a rough morphotype are more virulent than those with a smooth morphotype. Morphotype switch may occur during a clinical infection. To investigate the genes involved in colony morphotype switching, we performed transposon mutagenesis in a rough clinical strain of M. abscessus. A morphotype switching mutant (smooth) named mab_3083c::Tn was obtained. This mutant was found to have a lower aggregative ability and a higher sliding motility than the wild type strain. However, its glycopeptidolipid (GPL) content remained the same as those of the wild type. Complementation of the mutant with a functional mab_3083c gene reverted its morphotype back to rough, indicating that mab_3083c is associated with colony morphology of M. abscessus. Bioinformatic analyses showed that mab_3083c has a 75.4% identity in amino acid sequence with the well-characterized ribonuclease J (RNase J) of M. smegmatis (RNase JMsmeg). Complementation of the mutant with the RNase J gene of M. smegmatis also switched its colony morphology from smooth back to rough. These results suggest that Mab_3083c is a homologue of RNase J and involved in regulating M. abscessus colony morphotype switching.

scholarly journals Mutations of folC cause increased susceptibility to sulfamethoxazole in Mycobacterium tuberculosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruiqi Wang ◽  
Kun Li ◽  
Jifang Yu ◽  
Jiaoyu Deng ◽  
Yaokai Chen
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Clinical Isolates ◽  
Aminobenzoic Acid ◽  
Wild Type ◽  
Dihydropteroate Synthase ◽  
Expression Levels ◽  
Encoding Gene ◽  
Increased Susceptibility

AbstractPrevious studies showed that mutation of folC caused decreased expression of the dihydropteroate synthase encoding gene folP2 in Mycobacterium tuberculosis (M. tuberculosis). We speculated that mutation of folC in M. tuberculosis might affect the susceptibility to sulfamethoxazole (SMX). To prove this, 53 clinical isolates with folC mutations were selected and two folC mutants (I43A, I43T) were constructed based on M. tuberculosis H37Ra. The results showed that 42 of the 53 clinical isolates (79.2%) and the two lab-constructed folC mutants were more sensitive to SMX. To probe the mechanism by which folC mutations make M. tuberculosis more sensitive to SMX, folP2 was deleted in H37Ra, and expression levels of folP2 were compared between H37Ra and the two folC mutants. Although deletion of folP2 resulted in increased susceptibility to SMX, no difference in folP2 expression was observed. Furthermore, production levels of para-aminobenzoic acid (pABA) were compared between the folC mutants and the wild-type strain, and results showed that folC mutation resulted in decreased production of pABA. Taken together, we show that folC mutation leads to decreased production of pABA in M. tuberculosis and thus affects its susceptibility to SMX, which broadens our understanding of mechanisms of susceptibilities to antifolates in this bacterium.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

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