Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Microbiology (Reading) ; 158(Pt 5): 1183-1195, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22322962

RESUMEN

The ParB protein of Pseudomonas aeruginosa is important for growth, cell division, nucleoid segregation and different types of motility. To further understand its function we have demonstrated a vital role of the hydrophobic residues in the C terminus of ParB(P.a.). By in silico modelling of the C-terminal domain (amino acids 242-290) the hydrophobic residues L282, V285 and I289 (but not L286) are engaged in leucine-zipper-like structure formation, whereas the charged residues R290 and Q266 are implicated in forming a salt bridge involved in protein stabilization. Five parB mutant alleles were constructed and their functionality was defined in vivo and in vitro. In agreement with model predictions, the substitution L286A had no effect on mutant protein activities. Two ParBs with single substitutions L282A or V285A and deletions of two or seven C-terminal amino acids were impaired in both dimerization and DNA binding and were not able to silence genes adjacent to parS, suggesting that dimerization through the C terminus is a prerequisite for spreading on DNA. The defect in dimerization also correlated with loss of ability to interact with partner protein ParA. Reverse genetics demonstrated that a parB mutant producing ParB lacking the two C-terminal amino acids as well as mutants producing ParB with single substitution L282A or V285A had defects similar to those of a parB null mutant. Thus so far all the properties of ParB seem to depend on dimerization.


Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Unión al ADN/metabolismo , Multimerización de Proteína , Pseudomonas aeruginosa/genética , Sustitución de Aminoácidos , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Proteínas de Unión al ADN/genética , Silenciador del Gen , Leucina Zippers , Mutagénesis Sitio-Dirigida , Estructura Secundaria de Proteína , Pseudomonas aeruginosa/metabolismo , Genética Inversa , Eliminación de Secuencia
2.
Microbiology (Reading) ; 155(Pt 4): 1080-1092, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19332810

RESUMEN

Deletions leading to complete or partial removal of ParB were introduced into the Pseudomonas aeruginosa chromosome. Fluorescence microscopy of fixed cells showed that ParB mutants lacking the C-terminal domain or HTH motif formed multiple, less intense foci scattered irregularly, in contrast to the one to four ParB foci per cell symmetrically distributed in wild-type P. aeruginosa. All parB mutations affected both bacterial growth and swarming and swimming motilities, and increased the production of anucleate cells. Similar effects were observed after inactivation of parA of P. aeruginosa. As complete loss of ParA destabilized its partner ParB it was unclear deficiency of which protein is responsible for the mutant phenotypes. Analysis of four parB mutants showed that complete loss of ParB destabilized ParA whereas three mutants that retained the N-terminal 90 aa of ParB did not. As all four parB mutants demonstrate the same defects it can be concluded that either ParB, or ParA and ParB in combination, plays an important role in nucleoid distribution, growth and motility in P. aeruginosa.


Asunto(s)
Proteínas Bacterianas/genética , Segregación Cromosómica , Eliminación de Gen , Secuencias Hélice-Giro-Hélice/genética , Pseudomonas aeruginosa/crecimiento & desarrollo , Pseudomonas aeruginosa/fisiología , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Escherichia coli K12/genética , Regulación Bacteriana de la Expresión Génica , Movimiento , Fenotipo , Pseudomonas aeruginosa/genética , Transformación Bacteriana
3.
Nucleic Acids Res ; 30(4): 1046-55, 2002 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-11842117

RESUMEN

Active partitioning of low-copy number plasmids requires two proteins belonging to the ParA and ParB families and a cis-acting site which ParB acts upon. Active separation of clusters of plasmid molecules to the defined locations in the cell before cell division ensures stable inheritance of the plasmids. The central control operon of IncP-1 plasmids codes for regulatory proteins involved in the global transcriptional control of operons for vegetative replication, stable maintenance and conjugative transfer. Two of these proteins, IncC and KorB, also play a role in active partitioning, as the ParA and ParB homologues, respectively. Here we describe mapping the regions in KorB responsible for four of its different functions: dimerisation, DNA binding, repression of transcription and interaction with IncC. For DNA binding, amino acids E151 to T218 are essential, while repression depends not only on DNA binding but, additionally, on the adjacent region amino acids T218 to R255. The C-terminus of KorB is the main dimerisation domain but a secondary oligomerisation region is located centrally in the region from amino acid I174 to T218. Using three different methods (potentiation of transcriptional repression, potentiation of DNA binding and activation in the yeast two-hybrid system) we identify this region as also responsible for interactions with IncC. This IncC-KorB contact differs in location from the ParA-ParB/SopA-SopB interactions in P1/F but is similar to these systems in lying close to a masked oligomerisation determinant.


Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/fisiología , Plásmidos , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Reactivos de Enlaces Cruzados/química , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Dimerización , Glutaral/química , Datos de Secuencia Molecular , Estructura Terciaria de Proteína , Proteínas Represoras/genética , Proteínas Represoras/fisiología , Eliminación de Secuencia , Homología de Secuencia de Aminoácido , Técnicas del Sistema de Dos Híbridos
4.
Int Arch Allergy Immunol ; 106(1): 92-4, 1995 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-7812172

RESUMEN

Two female patients have been described in whom peripheral vasculitis with cold sensitivity preceded by about 5 years typical symptoms of aspirin-induced asthma. Vasculitis was immunologically mediated and took the form of either limited cutaneous scleroderma or perniosis. Antinuclear autoantibodies of SS-B specificity were present in the serum. Challenge with aspirin provoked asthma and distinct blood circulation disturbance in the hands. It is speculated that in these patients vasculitis and asthma were causally linked, and leukotrienes mediated bronchial and vascular reactions that occurred simultaneously following aspirin administration.


Asunto(s)
Asma/inducido químicamente , Vasculitis/complicaciones , Adulto , Aspirina/efectos adversos , Asma/inmunología , Autoanticuerpos/sangre , Femenino , Humanos , Persona de Mediana Edad , Vasculitis/tratamiento farmacológico , Vasculitis/inmunología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA