scholarly journals The cyanobacterial taxis protein HmpF regulates type IV pilus activity in response to light

2021 ◽  
Vol 118 (12) ◽  
pp. e2023988118
Author(s):  
Thomas V. Harwood ◽  
Esthefani G. Zuniga ◽  
HoJun Kweon ◽  
Douglas D. Risser
Keyword(s):  
Direct Interaction ◽  
Filamentous Cyanobacterium ◽  
Unicellular Cyanobacterium ◽  
Protein Protein Interaction ◽  
Type Iv ◽  
Carbonyl Cyanide ◽  
Chemotaxis Proteins ◽  
Surface Motility ◽  
Favorable Light ◽  
Insight Into

Motility is ubiquitous in prokaryotic organisms including the photosynthetic cyanobacteria where surface motility powered by type 4 pili (T4P) is common and facilitates phototaxis to seek out favorable light environments. In cyanobacteria, chemotaxis-like systems are known to regulate motility and phototaxis. The characterized phototaxis systems rely on methyl-accepting chemotaxis proteins containing bilin-binding GAF domains capable of directly sensing light, and the mechanism by which they regulate the T4P is largely undefined. In this study we demonstrate that cyanobacteria possess a second, GAF-independent, means of sensing light to regulate motility and provide insight into how a chemotaxis-like system regulates the T4P motors. A combination of genetic, cytological, and protein–protein interaction analyses, along with experiments using the proton ionophore carbonyl cyanide m-chlorophenyl hydrazine, indicate that the Hmp chemotaxis-like system of the model filamentous cyanobacterium Nostoc punctiforme is capable of sensing light indirectly, possibly via alterations in proton motive force, and modulates direct interaction between the cyanobacterial taxis protein HmpF, and Hfq, PilT1, and PilT2 to regulate the T4P motors. Given that the Hmp system is widely conserved in cyanobacteria, and the finding from this study that orthologs of HmpF and T4P proteins from the distantly related model unicellular cyanobacterium Synechocystis sp. strain PCC6803 interact in a similar manner to their N. punctiforme counterparts, it is likely that this represents a ubiquitous means of regulating motility in response to light in cyanobacteria.

scholarly journals Interspecies signaling generates exploratory motility in Pseudomonas aeruginosa

2019 ◽  
Author(s):  
Dominique H. Limoli ◽  
Niles P. Donegan ◽  
Elizabeth A. Warren ◽  
Ambrose L. Cheung ◽  
George A. O’Toole
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Chronic Illnesses ◽  
Community Members ◽  
Type Iv ◽  
Secreted Factors ◽  
Surrounding Environment ◽  
Modify Surface ◽  
Surface Motility ◽  
The Individual ◽  
Insight Into

AbstractMicrobes often live in multispecies communities where interactions among community members impact both the individual constituents and the surrounding environment. Here, we developed a system to visualize interspecies behaviors at initial encounters. By imaging two prevalent pathogens known to be coisolated from chronic illnesses, Pseudomonas aeruginosa and Staphylococcus aureus, we observed P. aeruginosa can modify surface motility in response to secreted factors from S. aureus. Upon sensing S. aureus, P. aeruginosa transitioned from collective to single-cell motility with an associated increase in speed and directedness – a behavior we refer to as ‘exploratory motility’. Through modulation of cAMP, explorer cells moved preferentially towards S. aureus and invaded S. aureus colonies through the action of the type IV pili. These studies reveal previously undescribed motility behaviors and lend insight into how P. aeruginosa senses and responds to other species. Identifying strategies to harness these interactions may open avenues for new antimicrobial strategies.

Retinoschisis and Norrie Disease: A missing link

2021 ◽  
Author(s):  
Rahini Rajendran ◽  
Sudha Dhandayuthapani ◽  
Subbulakshmi Chidambaram ◽  
Hemavathy Nagarajan ◽  
Umashankar Vetrivel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Functional Relationship ◽  
Direct Interaction ◽  
Specific Protein ◽  
Knock Out ◽  
Norrie Disease ◽  
Protein Protein Interaction ◽  
Protein Interactome ◽  
Molecular Relationships

Abstract Objective: Retinoschisis and Norrie disease are X-linked recessive retinal disorders caused by mutations in RS1 and NDP genes respectively. Both are likely to be monogenic and no locus heterogeneity has been reported. However, there are reports showing overlapping features of Norrie disease and retinoschisis in a NDP knock-out mouse model and also the involvement of both the genes in retinoschisis patients. Yet, the exact molecular relationships between the two disorders have still not been understood. The study investigated the association between retinoschisin (RS1) and norrin (NDP) using in vitro and in silico approaches. Specific protein-protein interaction between RS1 and NDP was analyzed in human retina by co-immunoprecipitation assay and MALDI-TOF mass spectrometry. STRING database was used to explore the functional relationship. Result: Co-immunoprecipitation demonstrated lack of a direct interaction between RS1 and NDP and was further substantiated by mass spectrometry. However, STRING revealed a potential indirect functional association between the two proteins. Progressively, our analyses indicate that FZD4 protein interactome via PLIN2 as well as the MAP kinase signaling pathway to be a likely link bridging the functional relationship between retinoschisis and Norrie disease.

Nuclear location of PLA2-I in proliferative cells

1998 ◽  
Vol 111 (7) ◽  
pp. 985-994 ◽  
Author(s):  
J.M. Fayard ◽  
C. Tessier ◽  
J.F. Pageaux ◽  
M. Lagarde ◽  
C. Laugier
Keyword(s):  
Binding Sites ◽  
Culture Medium ◽  
Aristolochic Acid ◽  
Direct Interaction ◽  
Nuclear Level ◽  
Proliferative Effect ◽  
Stromal Cell Line ◽  
Normal Rat ◽  
Nuclear Location ◽  
Insight Into

We have previously demonstrated that pancreatic PLA2 (PLA2-I) stimulates the proliferation of UIII cells, a stromal cell line derived from normal rat uterus. In order to gain further insight into the mechanism of action of PLA2-I, we have investigated the intracellular processing of PLA2-I. Either highly proliferative or growth arrested UIII cells were analyzed. Growth arrested cells were obtained from a contact inhibited monolayer or from aristolochic acid-treated cultures. Using cellular fractionation, western blotting, immunocytochemistry and confocal microscopy, we demonstrate that endogenous PLA2-I was mainly located in the nucleus in highly proliferative cells whereas its location was cytoplasmic in non proliferative cells. When non confluent UIII cells were incubated with nanomolar amounts of exogenous PLA2-I, the enzyme was internalized and, in the majority of cells, appeared within the nucleus. Both internalization and nuclear location of exogenous PLA2-I were suppressed by the addition of aristolochic acid to the culture medium. Binding experiments performed on purified nuclear preparations showed the presence of specific cooperative binding sites for PLA2-I. Collectively our data suggest that the proliferative effect exerted by pancreatic PLA2 in UIII cells is mediated by a direct interaction of the enzyme at the nuclear level. Putative mechanisms and targets are discussed.

scholarly journals Cyanobacteria use micro-optics to sense light direction

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Nils Schuergers ◽  
Tchern Lenn ◽  
Ronald Kampmann ◽  
Markus V Meissner ◽  
Tiago Esteves ◽  
...  
Keyword(s):  
Light Intensity ◽  
Light Source ◽  
Type Iv Pili ◽  
Small Cells ◽  
Unicellular Cyanobacterium ◽  
Light Sensing ◽  
High Resolution Image ◽  
Type Iv ◽  
Micro Optics ◽  
Synechocystis Sp

Bacterial phototaxis was first recognized over a century ago, but the method by which such small cells can sense the direction of illumination has remained puzzling. The unicellular cyanobacterium Synechocystis sp. PCC 6803 moves with Type IV pili and measures light intensity and color with a range of photoreceptors. Here, we show that individual Synechocystis cells do not respond to a spatiotemporal gradient in light intensity, but rather they directly and accurately sense the position of a light source. We show that directional light sensing is possible because Synechocystis cells act as spherical microlenses, allowing the cell to see a light source and move towards it. A high-resolution image of the light source is focused on the edge of the cell opposite to the source, triggering movement away from the focused spot. Spherical cyanobacteria are probably the world’s smallest and oldest example of a camera eye.

scholarly journals Comparative proteomics—network analysis of proteins responsible for ursolic acid–induced cytotoxicity in colorectal cancer cells

Tumor Biology ◽  
2017 ◽  
Vol 39 (3) ◽  
pp. 101042831769501 ◽  
Author(s):  
Qiaoyan Cai ◽  
Jing Lin ◽  
Ling Zhang ◽  
Jiumao Lin ◽  
Lili Wang ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cells ◽  
Ursolic Acid ◽  
Protein Interactions ◽  
Direct Interaction ◽  
Interaction Network ◽  
Two Dimensional Gel Electrophoresis ◽  
Cellular Targets ◽  
Protein Protein Interaction ◽  
Colorectal Cancer Cells

Ursolic acid is a key active compound present in many medicinal herbs that have been widely used in traditional Chinese medicine for the clinical treatment of various cancers. However, the precise mechanisms of its antitumor activity have been poorly understood. To identify the cellular targets of ursolic acid, two-dimensional gel electrophoresis combined with mass spectrometry was performed in this study, which identified 15 proteins with significantly altered levels in protein expression. This demonstrated that ursolic acid–induced cytotoxicity in colorectal cancer cells involves dysregulation in protein folding, signal transduction, cell proliferation, cell cycle, and apoptosis. Corresponding protein regulation was also confirmed by Western blotting. Furthermore, the study of functional association between these 15 proteins revealed that 10 were closely related in a protein–protein interaction network, whereby the proteins either had a direct interaction with each other or were associated via only one intermediary protein. In this instance, the ATP5B/CALR/HSP90B1/HSPB1/HSPD1-signaling network was revealed as the predominant target which was associated with the majority of the observed protein–protein interactions. As a result, the identified targets may be useful in explaining the anticancer mechanisms of ursolic acid and as potential targets for colorectal cancer therapy.

scholarly journals Genetic analysis of surface motility in Acinetobacter baumannii

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2534-2544 ◽  
Author(s):  
Katy M. Clemmer ◽  
Robert A. Bonomo ◽  
Philip N. Rather
Keyword(s):  
Quorum Sensing ◽  
Acinetobacter Baumannii ◽  
Null Allele ◽  
De Novo ◽  
Type Iv ◽  
Lytic Transglycosylase ◽  
Outer Membrane Porin ◽  
Surfactant Production ◽  
Surface Motility

The Gram-negative pathogen Acinetobacter baumannii strain M2 was found to exhibit a robust surface motility on low-percentage (0.2–0.4 %) agar plates. These patterns of motility were dramatically different depending on whether Difco or Eiken agar was used. Motility was observed in many, but not all, clinical and environmental isolates. The use of drop collapse assays to demonstrate surfactant production was unsuccessful, and the role of surfactants in A. baumannii M2 motility remains unclear. Surface motility was impaired by an insertion in pilT, encoding a gene product that is often required for retraction of the type IV pilus. Motility was also dependent on quorum sensing, as a null allele in the abaI autoinducer synthase decreased motility, and the addition of exogenous N-(3-hydroxy)-dodecanoylhomoserine lactone (3-OH C12-HSL) restored motility to the abaI mutant. Transposon mutagenesis was used to identify additional genes required for motility and revealed loci encoding various functions: non-ribosomal synthesis of a putative lipopeptide, a sensor kinase (BfmS), a lytic transglycosylase, O-antigen biosynthesis (RmlB), an outer membrane porin (OmpA) and de novo purine biosynthesis (PurK). Two of the above genes required for motility were highly activated by quorum sensing, and may explain, in part, the requirement for quorum sensing in motility.

scholarly journals Synergistic defects in pre-rRNA processing from mutations in the U3-specific protein Rrp9 and U3 snoRNA

2020 ◽  
Vol 48 (7) ◽  
pp. 3848-3868 ◽  
Author(s):  
Guillaume Clerget ◽  
Valérie Bourguignon-Igel ◽  
Nathalie Marmier-Gourrier ◽  
Nicolas Rolland ◽  
Ludivine Wacheul ◽  
...  
Keyword(s):  
Protein Interaction Network ◽  
18S Rrna ◽  
Direct Interaction ◽  
Interaction Network ◽  
Specific Protein ◽  
Rrna Processing ◽  
Protein Protein Interaction ◽  
U3 Snorna ◽  
Ssu Processome ◽  
Protein Protein Interaction Network

Abstract U3 snoRNA and the associated Rrp9/U3-55K protein are essential for 18S rRNA production by the SSU-processome complex. U3 and Rrp9 are required for early pre-rRNA cleavages at sites A0, A1 and A2, but the mechanism remains unclear. Substitution of Arg 289 in Rrp9 to Ala (R289A) specifically reduced cleavage at sites A1 and A2. Surprisingly, R289 is located on the surface of the Rrp9 β-propeller structure opposite to U3 snoRNA. To understand this, we first characterized the protein-protein interaction network of Rrp9 within the SSU-processome. This identified a direct interaction between the Rrp9 β-propeller domain and Rrp36, the strength of which was reduced by the R289A substitution, implicating this interaction in the observed processing phenotype. The Rrp9 R289A mutation also showed strong synergistic negative interactions with mutations in U3 that destabilize the U3/pre-rRNA base-pair interactions or reduce the length of their linking segments. We propose that the Rrp9 β-propeller and U3/pre-rRNA binding cooperate in the structure or stability of the SSU-processome. Additionally, our analysis of U3 variants gave insights into the function of individual segments of the 5′-terminal 72-nt sequence of U3. We interpret these data in the light of recently reported SSU-processome structures.

scholarly journals Type IV pilin is glycosylated in Pseudomonas syringae pv. tabaci 6605 and is required for surface motility and virulence

2012 ◽  
Vol 13 (7) ◽  
pp. 764-774 ◽  
Author(s):  
LINH CHI NGUYEN ◽  
FUMIKO TAGUCHI ◽  
QUANG MINH TRAN ◽  
KANA NAITO ◽  
MASANOBU YAMAMOTO ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iv ◽  
Type Iv Pilin ◽  
Surface Motility

scholarly journals Canstatin induces apoptosis in gastric cancer xenograft growth in mice through the mitochondrial apoptotic pathway

2014 ◽  
Vol 34 (2) ◽  
Author(s):  
Ya-Nan Xing ◽  
Peng Deng ◽  
Hui-Mian Xu
Keyword(s):  
Gastric Cancer ◽  
Xenograft Model ◽  
Inhibitory Effect ◽  
Collagen Type Iv ◽  
Valuable Insight ◽  
Apoptotic Pathway ◽  
Type Iv ◽  
Collagenous Domain ◽  
Insight Into ◽  
Gastric Cancer Xenograft

Canstatin, the non-collagenous domain of collagen type IV α-chains, belongs to a series of collagen-derived angiogenic inhibitors. In this study, the inhibitory effect of recombinant canstatin on tumour growth was investigated using a gastric cancer xenograft model. The volume and weight of tumours in mice treated with canstatin were lower than that in mice treated with PBS. Accordingly, the survival rate of these mice was significantly higher than that of mice bearing tumours treated with PBS. Moreover, valuable insight into the mechanisms mediated by canstatin was obtained.

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