Identification and Classification of a Two-Component System Based on Domain Structures in Bacteria and Differences in Domain Structure between Gram-Positive and Gram-Negative Bacteria

2010 ◽  
Vol 74 (4) ◽  
pp. 716-720 ◽  
Author(s):  
Sangwan KIM ◽  
Hideki HIRAKAWA ◽  
Shigeru MUTA ◽  
Satoru KUHARA
Keyword(s):  
Domain Structure ◽  
Gram Negative Bacteria ◽  
Two Component System ◽  
Gram Positive ◽  
Component System ◽  
Gram Negative ◽  
Domain Structures ◽  
Two Component

scholarly journals Regulatory Roles of the GacS/GacA Two-Component System in Plant-Associated and Other Gram-Negative Bacteria

2001 ◽  
Vol 14 (12) ◽  
pp. 1351-1363 ◽  
Author(s):  
Stephan Heeb ◽  
Dieter Haas
Keyword(s):  
Rna Binding ◽  
Enteric Bacteria ◽  
Plant Diseases ◽  
Gram Negative Bacteria ◽  
Two Component System ◽  
Component System ◽  
Gram Negative ◽  
Ecological Fitness ◽  
Two Component ◽  
Sensor Kinases

The sensor kinase GacS and the response regulator GacA are members of a two-component system that is present in a wide variety of Gram-negative bacteria and has been studied mainly in enteric bacteria and fluorescent pseudomonads. The GacS/GacA system controls the production of secondary metabolites and extracellular enzymes involved in pathogenicity to plants and animals, biocontrol of soilborne plant diseases, ecological fitness, or tolerance to stress. A current model proposes that GacS senses a still-unknown signal and activates, via a phosphorelay mechanism, the GacA transcription regulator, which in turn triggers the expression of target genes. The GacS protein belongs to the unorthodox sensor kinases, characterized by an autophosphorylation, a receiver, and an output domain. The periplasmic loop domain of GacS is poorly conserved in diverse bacteria. Thus, a common signal interacting with this domain would be unexpected. Based on a comparison with the transcriptional regulator NarL, a secondary structure can be predicted for the GacA sensor kinases. Certain genes whose expression is regulated by the GacS/GacA system are regulated in parallel by the small RNA binding protein RsmA (CsrA) at a posttranscriptional level. It is suggested that the GacS/GacA system operates a switch between primary and secondary metabolism, with a major involvement of posttranscriptional control mechanisms.

scholarly journals Potentiation of photoinactivation of Gram-positive and Gram-negative bacteria mediated by six phenothiazinium dyes by addition of azide ion

2014 ◽  
Vol 13 (11) ◽  
pp. 1541-1548 ◽  
Author(s):  
Kamola R. Kasimova ◽  
Magesh Sadasivam ◽  
Giacomo Landi ◽  
Tadeusz Sarna ◽  
Michael R. Hamblin
Keyword(s):  
Singlet Oxygen ◽  
Hydroxyl Radicals ◽  
Gram Negative Bacteria ◽  
Photodynamic Inactivation ◽  
Gram Positive ◽  
Gram Negative ◽  
Azide Ion

Antimicrobial photodynamic inactivation (APDI) using six different phenothiazinium dyes is mediated by singlet oxygen (quenched by azide) and hydroxyl radicals (potentiated by azide) depending on Gram-classification of the bacteria and whether the dye is washed from the cells.

How the PhoP/PhoQ System Controls Virulence and Mg 2+ Homeostasis: Lessons in Signal Transduction, Pathogenesis, Physiology, and Evolution

2021 ◽  
Author(s):  
Eduardo A. Groisman ◽  
Alexandre Duprey ◽  
Jeongjoon Choi
Keyword(s):  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Transcriptional Regulator ◽  
Acidic Ph ◽  
Two Component System ◽  
Component System ◽  
Gram Negative ◽  
Content Type ◽  
Two Component ◽  
Serovar Typhimurium

The PhoP/PhoQ two-component system governs virulence, Mg 2+ homeostasis, and resistance to a variety of antimicrobial agents, including acidic pH and cationic antimicrobial peptides, in several Gram-negative bacterial species. Best understood in Salmonella enterica serovar Typhimurium, the PhoP/PhoQ system consists of the sensor PhoQ and the transcriptional regulator PhoP.

scholarly journals YbfA Regulates the Sensitivity of Escherichia coli K12 to Plantaricin BM-1 via the BasS/BasR Two-Component Regulatory System

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyue Chen ◽  
Yifei Liu ◽  
Junhua Jin ◽  
Hui Liu ◽  
Yanling Hao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Metabolic Pathways ◽  
Gram Negative Bacteria ◽  
Two Component System ◽  
Proteomics Analysis ◽  
Component System ◽  
E Coli ◽  
Two Component ◽  
And Function

Plantaricin BM-1, a class IIa bacteriocin produced by Lactobacillus plantarum BM-1, shows obvious antibacterial activity against Escherichia coli. However, the mechanism underlying the action of class IIa bacteriocins against gram-negative bacteria remains to be explored. The purpose of this study was to investigate the role of YbfA, a DUF2517 domain-containing protein, in the response of Escherichia coli K12 to plantaricin BM-1. The growth curve experiment and MIC experiment showed that the sensitivity of E. coli to plantaricin BM-1 was decreased by a ybfA null mutation. Electron microscopy showed that the ybfA null mutation reduced the surface rupture and contraction caused by plantaricin BM-1, and mitigated the effect of plantaricin BM-1 on the morphology of the E. coli cell membrane. Proteomics analysis showed that 323 proteins were differentially expressed in E. coli lacking the ybfA gene (P < 0.05); 118 proteins were downregulated, and 205 proteins were upregulated. The metabolic pathways containing the upregulated proteins mainly included outer membrane proteins, integral components of the plasma membrane, regulation of cell motility, and regulation of locomotion. The metabolic pathways involving the downregulated proteins mainly included outer membrane protein glycine betaine transport, amino-acid betaine transport, and transmembrane signaling receptor activity. The results of the proteomics analysis showed that the protein expression of the BasS/BasR two-component system was significantly increased (P < 0.05). Moreover, the expression levels of downstream proteins regulated by this two-component system were also significantly increased, including DgkA, FliC, and MlaE, which are involved in cell membrane structure and function, and RT-qPCR also confirmed this result. The growth curve showed that the sensitivity of E. coli to plantaricin BM-1 was significantly increased due to deletion of the BasS/BasR two-component system. Thus, deletion of ybfA in E. coli can increase the expression of the BasS/BasR two-component system and positively regulate the structure and function of the cell membrane to reduce the sensitivity to plantaricin BM-1. This will help to explore the mechanism of action of class IIa bacteriocins against gram-negative bacteria.

scholarly journals Various novel colistin resistance mechanisms interact to facilitate adaptation of Aeromonas hydrophila to complex colistin environments

2021 ◽  
Author(s):  
Junqi Liu ◽  
Gang Xiao ◽  
Wangping Zhou ◽  
Jun Yang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Aeromonas Hydrophila ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Bacterial Survival ◽  
Colistin Resistance ◽  
Two Component System ◽  
Component System ◽  
Gram Negative ◽  
Two Component ◽  
High Level

Aeromonas hydrophila, a heterotrophic and Gram-negative bacterium, has attracted considerable attention owing to the increasing prevalence of reported infections. Colistin is a last-resort antibiotic that can treat life-threatening infections caused by multidrug-resistant gram-negative bacteria. However, the mechanisms underlying colistin resistance in A. hydrophila remain unclear. The present study reveals four novel colistin resistance mechanisms in A. hydrophila: (i) EnvZ/OmpR upregulates the expression of the arnBCADTEF operon to mediate LPS modification by 4-amino-4-deoxy-L-arabinose; (ii) EnvZ/OmpR regulates the expression of the autotransporter gene3832 to decrease outer membrane permeability in response to colistin; (iii) deletion of envZ/ompR activates PhoP/PhoQ, which functions as a substitute two-component system to mediate the addition of phosphoethanolamine to lipid A via pmrC; and (iv) the mlaFD173A mutant confers high-level colistin resistance via upregulation of the Mla pathway. The EnvZ/OmpR two-component system-mediated resistance mechanism is the leading form of colistin resistance in A. hydrophila, which enables it to rapidly generate low- to medium-level colistin resistance. As colistin concentrations in the environment continue to rise, antibiotic resistance mediated by EnvZ/OmpR becomes insufficient to ensure bacterial survival. Consequently, A. hydrophila has developed a mlaF mutation that results in high-level colistin resistance. Our findings indicate that A. hydrophila can thrive in a complex environment through various colistin resistance mechanisms.

Classification of the Genes Involved in the Two-Component System of the MossPhyscomitrella patens

2010 ◽  
Vol 74 (12) ◽  
pp. 2542-2545 ◽  
Author(s):  
Kai ISHIDA ◽  
Takafumi YAMASHINO ◽  
Hanayo NAKANISHI ◽  
Takeshi MIZUNO
Keyword(s):  
Two Component System ◽  
Component System ◽  
Two Component

scholarly journals Colistin heteroresistance in Enterobacter cloacae is mediated by PmrAB-independent 4-amino-4-deoxy-L-arabinose addition to lipid A

2019 ◽  
Author(s):  
Katie N. Kang ◽  
Dustin R. Klein ◽  
Misha I. Kazi ◽  
François Guérin ◽  
Vincent Cattoir ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Lipid A ◽  
Enterobacter Cloacae ◽  
Two Component System ◽  
Cationic Antimicrobial Peptide ◽  
Component System ◽  
Gram Negative ◽  
Nosocomial Pathogens ◽  
Majority Population ◽  
Two Component

AbstractThe Enterobacter cloacae complex (ECC) consists of closely-related, but genetically distinct bacteria commonly associated with the human microbiota. ECC have been increasingly isolated from healthcare-associated infections, demonstrating that these Enterobacteriaceae are emerging nosocomial pathogens. ECC strains can rapidly acquire multidrug resistance to conventional antibiotics. Cationic antimicrobial peptides (CAMPs) have served as therapeutic alternatives because they target the highly conserved lipid A component of the Gram-negative outer membrane to lyse the bacterial cell. Many Gram-negative Enterobacteriaceae fortify their outer membrane with cationic amine-containing moieties to protect from CAMP-inflicted lysis. The PmrAB two-component system (TCS) transcriptionally activates 4-amino-4-deoxy-L-arabinose (L-Ara4N) biosynthesis to result in amine moiety addition to lipid A in many Enterobacteriaceae such as E. coli and Salmonella. In contrast, PmrAB in E. cloacae is dispensable for CAMP resistance. Instead, fitness against CAMPs presents as heteroresistance, or a subpopulation of cells that exhibit clinically significant increases in resistance levels compared to the majority population. We demonstrate that E. cloacae lipid A is modified with L-Ara4N to induce CAMP heteroresistance and that the regulatory mechanism is independent of the PmrABEcl TCS. We show that the response regulator, PhoPEcl, directly binds to the arnBEcl promoter to induce expression of L-Ara4N biosynthesis and PmrAB-independent addition to the lipid A disaccharolipid. Therefore, we have identified a mechanism of ECC colistin heteroresistance that directly involves the PhoPQ system.ImportanceMembers of the Enterobacter cloacae complex (ECC) are Gram-negative nosocomial pathogens that have emerged within healthcare facilities around the world. ECC infections are associated with immunocompromised patients and infections are often life threatening. The cationic antimicrobial peptide, colistin (polymyxin E), is a last-line treatment option to combat Gram-negative multidrug resistant infections. However, many ECC intrinsically encode a colistin heteroresistance mechanism. Our analysis to characterize colistin heteroresistance in E. cloacae revealed that 4-amino-4-deoxy-L-arabinose is conjugated to the lipid A disaccharolipid to protect from colistin-mediated lysis. Additionally, this mechanism is directly regulated by the PhoPQEcl two-component system. Elucidation of outer membrane antimicrobial resistance modifications and their regulatory pathways in E. cloacae isolates will advance our understanding of CAMP heteroresistance.

Rapid demonstration of septic or infectious arthritis due to Gram-negative bacteria

1992 ◽  
Vol 50 (1) ◽  
pp. 686-687
Author(s):  
Jacob S. Hanker ◽  
Paul R. Gross ◽  
Beverly L. Giammara
Keyword(s):  
Chronic Arthritis ◽  
Blood Cultures ◽  
Gram Negative Bacteria ◽  
Infectious Arthritis ◽  
Bacterial Arthritis ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Blood cultures are positive in approximately only 50 per cent of the patients with nongonococcal bacterial infectious arthritis and about 20 per cent of those with gonococcal arthritis. But the concept that gram-negative bacteria could be involved even in chronic arthritis is well-supported. Gram stains are more definitive in staphylococcal arthritis caused by gram-positive bacteria than in bacterial arthritis due to gram-negative bacteria. In the latter situation where gram-negative bacilli are the problem, Gram stains are helpful for 50% of the patients; they are only helpful for 25% of the patients, however, where gram-negative gonococci are the problem. In arthritis due to gram-positive Staphylococci. Gramstained smears are positive for 75% of the patients.

Dual stain kit for the microscopic gram classification of ocular infection bacteria

1993 ◽  
Vol 51 ◽  
pp. 248-249
Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara
Keyword(s):  
Contact Lenses ◽  
Ocular Infection ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Staining ◽  
Ocular Infections ◽  
Different Types ◽  
Culture Positive ◽  
Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

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