scholarly journals Transmembrane topology of the AbsA1 sensor kinase of Streptomyces coelicolor

Microbiology ◽  
2009 ◽  
Vol 155 (6) ◽  
pp. 1812-1818 ◽  
Author(s):  
Nancy L. McKenzie ◽  
Justin R. Nodwell
Keyword(s):  
Response Regulator ◽  
Streptomyces Coelicolor ◽  
Antibiotic Biosynthesis ◽  
Sensor Kinase ◽  
Response Mechanism ◽  
Transmembrane Topology ◽  
C Terminus ◽  
N Terminus ◽  
Sensor Kinases ◽  
Insight Into

The sensor kinase AbsA1 (SCO3225) phosphorylates the response regulator AbsA2 (SCO3226) and dephosphorylates AbsA2∼P. The phosphorylated response regulator represses antibiotic biosynthesis operons in Streptomyces coelicolor. AbsA1 was predicted to have an atypical transmembrane topology, and the location of its signal-sensing domain is not readily obvious. To better understand this protein and to gain insight into its signal response mechanism, we determined its transmembrane topology using fusions of absA1 to egfp, which is believed to be the first application of this approach to transmembrane topology in the actinomycetes. Our results are in agreement with the in silico topological predictions and demonstrate that AbsA1 has five transmembrane domains, four near the N terminus and one near the C terminus. Unlike most sensor kinases, the largest extracellular portion of AbsA1 is at the C terminus.

scholarly journals Biochemical Activities of the absA Two-Component System of Streptomyces coelicolor

2005 ◽  
Vol 187 (2) ◽  
pp. 687-696 ◽  
Author(s):  
Nancy L. Sheeler ◽  
Susan V. MacMillan ◽  
Justin R. Nodwell
Keyword(s):  
Transcriptional Repression ◽  
Kinase Activity ◽  
Response Regulator ◽  
Streptomyces Coelicolor ◽  
Point Mutations ◽  
Stable State ◽  
Sensor Kinase ◽  
Two Component System ◽  
Antibiotic Synthesis ◽  
Cognate Response Regulator

ABSTRACT The AbsA1 sensor kinase and its cognate response regulator AbsA2 are important regulators of antibiotic synthesis in Streptomyces coelicolor. While certain point mutations in absA1 reduce or eliminate the synthesis of several antibiotics, null mutations in these genes bring about enhanced antibiotic synthesis. We show here that AbsA1, which is unusual in sequence and structure, is both an AbsA2 kinase and an AbsA2∼P phosphatase. The half-life of AbsA2∼P in solution is 68.6 min, consistent with a role in maintaining a relatively stable state of transcriptional repression or activation. We find that mutations in the absA locus that enhance antibiotic synthesis impair AbsA2 kinase activity and that mutations that repress antibiotic synthesis impair AbsA2∼P phosphatase activity. These results support a model in which the phosphorylation state of AbsA2 is determined by the balance of the kinase and phosphatase activities of AbsA1 and where AbsA2∼P represses antibiotic biosynthetic genes either directly or indirectly.

scholarly journals The RNA Polymerase Omega Factor RpoZ Is Regulated by PhoP and Has an Important Role in Antibiotic Biosynthesis and Morphological Differentiation in Streptomyces coelicolor

2011 ◽  
Vol 77 (21) ◽  
pp. 7586-7594 ◽  
Author(s):  
Fernando Santos-Beneit ◽  
Mónica Barriuso-Iglesias ◽  
Lorena T. Fernández-Martínez ◽  
Miriam Martínez-Castro ◽  
Alberto Sola-Landa ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Response Regulator ◽  
Antibiotic Production ◽  
Streptomyces Coelicolor ◽  
Morphological Differentiation ◽  
Luciferase Reporter ◽  
Antibiotic Biosynthesis ◽  
Binding Assays ◽  
Content Type ◽  
Phosphate Depletion

ABSTRACTThe RNA polymerase (RNAP) omega factor (ω) forms a complex with the α2ββ′ core of this enzyme in bacteria. We have characterized therpoZgene ofStreptomyces coelicolor, which encodes a small protein (90 amino acids) identified as the omega factor. Deletion of therpoZgene resulted in strains with a slightly reduced growth rate, although they were still able to sporulate. The biosynthesis of actinorhodin and, particularly, that of undecylprodigiosin were drastically reduced in the ΔrpoZstrain, suggesting that expression of these secondary metabolite biosynthetic genes is dependent upon the presence of RpoZ in the RNAP complex. Complementation of the ΔrpoZmutant with the wild-typerpoZallele restored both phenotype and antibiotic production. Interestingly, therpoZgene contains a PHO box in its promoter region. DNA binding assays showed that the phosphate response regulator PhoP binds to such a region. Since luciferase reporter studies showed thatrpoZpromoter activity was increased in a ΔphoPbackground, it can be concluded thatrpoZis controlled negatively by PhoP, thus connecting phosphate depletion regulation with antibiotic production and morphological differentiation inStreptomyces.

Crystallization of a complex between a novel C-terminal transmitter, HPt domain, of the anaerobic sensor kinase ArcB and the chemotaxis response regulator CheY

1998 ◽  
Vol 54 (1) ◽  
pp. 140-142 ◽  
Author(s):  
Masato Kato ◽  
Takeshi Mizuno ◽  
Toshio Hakoshima
Keyword(s):  
Response Regulator ◽  
Diffusion Method ◽  
Sensor Kinase ◽  
Signal Transduction System ◽  
Hanging Drop ◽  
Receiver Domain ◽  
C Terminus ◽  
Cell Dimensions ◽  
Two Component Signal Transduction ◽  
Unit Cell Dimensions

The histidine-containing phosphotransfer (HPt) domain at the C-terminus of the anaerobic sensor kinase ArcB has been cocrystallized with the chemotaxis response regulator CheY by a hanging-drop vapor-diffusion method. Crystals belong to space group P212121 with unit-cell dimensions a = 55.32, b = 76.29 and c = 83.89 Å, with one molecule in the crystallographic asymmetric unit. The crystals diffract to 2.7 Å resolution. This is the first crystallization of a protein–protein complex formed by a transmitter domain of sensor kinase and a receiver domain of response regulator in the two-component signal-transduction system.

scholarly journals Mycobacterium tuberculosis DosS binds H2S through its Fe3+ heme iron to regulate the Dos dormancy regulon

2021 ◽  
Author(s):  
Ritesh R Sevalkar ◽  
Joel N Glasgow ◽  
Martin Pettinati ◽  
Marcelo A Martin ◽  
Vineel P Reddy ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Response Regulator ◽  
Heme Iron ◽  
Sensor Kinase ◽  
New Paradigm ◽  
Heme Pocket ◽  
Expression Of Genes ◽  
Sensor Kinases ◽  
Dynamics Simulations ◽  
Autokinase Activity

Mycobacterium tuberculosis (Mtb) senses and responds to host-derived gasotransmitters NO and CO via heme-containing sensor kinases DosS and DosT and the response regulator DosR. Hydrogen sulfide (H2S) is an important signaling molecule in mammals, but its role in Mtb physiology is unclear. We have previously shown that exogenous H2S can modulate expression of genes in the Dos dormancy regulon via an unknown mechanism(s). Here, we tested the hypothesis that Mtb senses and responds to H2S via the DosS/T/R system. Using UV-Vis and EPR spectroscopy, we show that H2S binds directly to the ferric (Fe3+) heme of DosS (KD = 5.64 uM) but not the ferrous (Fe2+) form. No interaction with DosT was detected. Thus, the mechanism by which DosS senses H2S is different from that for sensing NO and CO, which bind only the ferrous forms of DosS and DosT. Steered Molecular Dynamics simulations show that H2S, and not the charged HS- species, can enter the DosS heme pocket. We also show that H2S increases DosS autokinase activity and subsequent phosphorylation of DosR, and H2S-mediated increases in Dos regulon gene expression is lost in Mtb lacking DosS. Finally, we demonstrate that physiological levels of H2S in macrophages can induce Dos regulon genes via DosS. Overall, these data reveal a novel mechanism whereby Mtb senses and responds to a third host gasotransmitter, H2S, via DosS-Fe3+. These findings highlight the remarkable plasticity of DosS and establish a new paradigm for how bacteria can sense multiple gasotransmitters through a single heme sensor kinase.

scholarly journals Dimerization of ubiquilin is dependent upon the central region of the protein: evidence that the monomer, but not the dimer, is involved in binding presenilins

2006 ◽  
Vol 399 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Diana L. Ford ◽  
Mervyn J. Monteiro
Keyword(s):  
Central Region ◽  
Regulatory Mechanism ◽  
Active Form ◽  
Cellular Proteins ◽  
Interacting Protein ◽  
C Terminus ◽  
N Terminus ◽  
The Stability ◽  
Insight Into

Ubiquilin proteins have been shown to interact with a wide variety of other cellular proteins, often regulating the stability and degradation of the interacting protein. Ubiquilin contains a UBL (ubiquitin-like) domain at the N-terminus and a UBA (ubiquitin-associated) domain at the C-terminus, separated by a central region containing Sti1-like repeats. Little is known about regulation of the interaction of ubiquilin with other proteins. In the present study, we show that ubiquilin is capable of forming dimers, and that dimerization requires the central region of ubiquilin, but not its UBL or the UBA domains. Furthermore, we provide evidence suggesting that monomeric ubiquilin is likely to be the active form that is involved in binding presenilin proteins. Our results provide new insight into the regulatory mechanism underlying the interaction of ubiquilin with presenilins.

scholarly journals The N Terminus of the Transmembrane Protein BP180 Interacts with the N-terminal Domain of BP230, Thereby Mediating Keratin Cytoskeleton Anchorage to the Cell Surface at the Site of the Hemidesmosome

2000 ◽  
Vol 11 (1) ◽  
pp. 277-286 ◽  
Author(s):  
Susan B. Hopkinson ◽  
Jonathan C. R. Jones
Keyword(s):  
Cell Surface ◽  
Bullous Pemphigoid ◽  
Transmembrane Protein ◽  
Terminal Fragment ◽  
C Terminus ◽  
N Terminus ◽  
Α6β4 Integrin ◽  
Two Hybrid ◽  
Insight Into

In epidermal cells, the keratin cytoskeleton interacts with the elements in the basement membrane via a multimolecular junction called the hemidesmosome. A major component of the hemidesmosome plaque is the 230-kDa bullous pemphigoid autoantigen (BP230/BPAG1), which connects directly to the keratin-containing intermediate filaments of the cytoskeleton via its C terminus. A second bullous pemphigoid antigen of 180 kDa (BP180/BPAG2) is a type II transmembrane component of the hemidesmosome. Using yeast two-hybrid technology and recombinant proteins, we show that an N-terminal fragment of BP230 can bind directly to an N-terminal fragment of BP180. We have also explored the consequences of expression of the BP230 N terminus in 804G cells that assemble hemidesmosomes in vitro. Unexpectedly, this fragment disrupts the distribution of BP180 in transfected cells but has no apparent impact on the organization of endogenous BP230 and α6β4 integrin. We propose that the BP230 N terminus competes with endogenous BP230 protein for BP180 binding and inhibits incorporation of BP180 into the cell surface at the site of the hemidesmosome. These data provide new insight into those interactions of the molecules of the hemidesmosome that are necessary for its function in integrating epithelial and connective tissue types.

Preparation and properties of three analogues of [5-leucine]enkephalin, substrates for enzyme conversion studies

1985 ◽  
Vol 50 (6) ◽  
pp. 1329-1334
Author(s):  
Jaroslav Vičar ◽  
Linda Servítová ◽  
Martin Flegel ◽  
Karel Hauzer ◽  
Tomislav Barth
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Guinea Pig ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Guinea Pig Ileum ◽  
Opioid Activity ◽  
C Terminus ◽  
N Terminus ◽  
Fragment Condensation

Analogues of [5-Leu]enkephalin, prolonged by methionine on the N-terminus or, by lysine or methionine on the C-terminus were prepared by fragment condensation, purified by ion exchange chromatography or high-pressure liquid chromatography. The substances were characterised by their opioid activity in a test on guinea-pig ileum in comparison with the activity of [5-Leu]enkephalin.

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