Buscar en
Enfermedades Infecciosas y Microbiología Clínica
Toda la web
Inicio Enfermedades Infecciosas y Microbiología Clínica Estructura y función de los integrones
Información de la revista
Vol. 20. Núm. 7.
Páginas 341-345 (Agosto 2002)
Compartir
Compartir
Descargar PDF
Más opciones de artículo
Vol. 20. Núm. 7.
Páginas 341-345 (Agosto 2002)
Acceso a texto completo
Estructura y función de los integrones
Structure and function of integrons
Visitas
43675
Montserrat Sabaté, Guillem Prats1
Autor para correspondencia
gprats@cs.vhebron.es

Correspondencia: Dr. G. Prats. Dirección actual: Servicio de Microbiología. Hospital de la Vall d’Hebron. P.° Vall d’Hebron, s/n. 08035 Barcelona. España.
Servicio de Microbiología. Hospital de la Santa Creu i Sant Pau. Universitat Autònoma de Barcelona. España
Este artículo ha recibido
Información del artículo
Resumen
Bibliografía
Descargar PDF
Estadísticas

Los integrones son unas piezas genéticas que han despertado gran interés porque algunos de ellos vehiculan genes de resistencia a los antimicrobianos. Desde el extremo 5’ al 3’ están formados por un fragmento que codifica una integrasa (intI) y a continuación una secuencia attI a la que se unen los genes de resistencia. Dentro de intI, en su extremo 3’, hay una secuencia promotora Pant a partir de la cual se transcriben los genes de resistencia integrados, ya que estos genes carecen de promotor.

En efecto, la integrasa reconoce en ciertos genes de resistencia (denominados genes casete) una secuencia específica denominada 59-be, que une, por recombinación, a la secuencia attI del integrón. El fragmento formado por intI-attI está altamente conservado en todos los integrones y se denomina 5’-CS.

Los integrones se han clasificado según la secuencia de su integrasa. Los detectados con más frecuencia en cepas aisladas en clínica pertenecen a la clase 1. Los integrones de la clase 1 están formados por el 5’-CS y a continuación se sitúan los diferentes genes casetes captados, por lo que constituye una zona variable y, finalmente, hay una zona conservada denominada 3’-CS formada por 2 genes uno de resistencia a compuestos de amonio cuaternario (qacEδI) y otro a sulfamidas (sul1); estos 2 genes, no son casetes y, por lo tanto, no son móviles sino fijos. La estructura de uno de estos integrones vendría representada por IntI-attI [R1+R2+…]-qacEδ1-sul1.

Probablemente, los integrones no son móviles por sí mismos, pero con frecuencia se hallan en transposones que a su vez se encuentran en plásmidos conjugativos, por lo que su movilidad horizontal está asegurada, como se constata por su amplia difusión entre las bacterias.

Palabras clave:
Integrones
Resistencia
Antimicrobianos

Integrons are genetic elements known for their role in the acquisition and expression of genes conferring antibiotic resistance. Integrons have an integrase gene (intI), an attachment site (attI), into which individual resistance genes are inserted and a promotor sequence (Pant), allowing expression of resistance genes (cassette-associated genes), which do not have promotors. Integrase recognizes 59-be, a specific sequence in certain resistance genes, which is captured by recombination at the attI attachment site. The fragment intI - attI is highly conserved in all integrons and is called 5’-CS.

Integrons have been classified according to the sequence of their integrase and the ones most frequently detected in isolated clinical strains belong to Class I. Class I integrons contain the 5’-CS region followed by gene cassettes in a variable region and finally, a conserved region known as 3’-CS containing two genes, the quaternary ammonium resistance gene (qacEδI) and the sulphonamide resistance gene (sul1); both genes are fixed in this structure. Accordingly, the structure of a Class 1 integron would be IntI - attI [R1+R2+…] - qacEδ1 - sul1.

Integrons are probably not mobile, but they are often found in transposons within conjunctive plasmids, which assures their mobility, as can be seen by their wide diffusion among bacteria.

Keywords:
Integrons
Resistance
Antimicrobials
El Texto completo está disponible en PDF
Bibliografía
[1.]
Sabaté M, Navarro F, Miró E, Campoy S, Mirelis B, Barbé J, et al. A novel complex sul1-type integron in Escherichia coli carrying the blaCTX-M-9 gene. Antimicrob Agents Chemother. En prensa.
[2.]
H.W. Stokes, R.M. Hall.
A novel family of potencially mobile DNA elements encoding site-specific gene-integration functions: integrons.
Mol Microbiol, 3 (1989), pp. 1669-1683
[3.]
P.A. White, C.J. McIver, W.D. Rawlinson.
Integrons and gene cassettes in the enterobacteriaceae.
Antimicrob Agents Chemother, 45 (2001), pp. 2658-2661
[4.]
D.A. Rowe-Magnus, A.M. Guerout, P. Ploncard, B. Dychinco, J. Davies, D. Mazel.
The evolutionary history of chromosomal super-integrons provides an ancestry for multiresistant integrons.
Microbiology, 98 (2001), pp. 652-657
[5.]
S.J. Rosser, H.K. Young.
Identification and characterization of class 1 integrons in bacteria from an aquatic environment.
J Antimicrob Chemother, 44 (1999), pp. 11-18
[6.]
A.C. Fluit, F.J. Schmitz.
Class 1 integrons, gene cassettes, mobility, and epidemiology.
Eur J Clin Microbiol Infect Dis, 18 (1999), pp. 761-770
[7.]
J. Nesvera, J. Hochmannova, M. Patek.
An integron of class 1 is present on the plasmid pCG4 from gram-positive bacterium Corynebacterium glutamicum.
FEMS Microbiol Lett, 169 (1998), pp. 391-395
[8.]
G.D. Recchia, R.M. Hall.
Gene cassettes: A new class of mobile element.
Microbiology, 141 (1995), pp. 3015-3027
[9.]
M. Ouellette, P.H. Roy.
Homology of ORFs from Tn2603 and from R46 to site-specific recombinases.
Nucleic Acids Res, 15 (1987), pp. 10055
[10.]
M.V. Francia, F. De la Cruz, M. García Lobo.
Secondary sites for integration mediated by Tn21 integrase.
Mol Microbiol, 10 (1993), pp. 823-828
[11.]
G.D. Recchia, R.M. Hall.
Plasmid evolution by acquisition of mobile gene cassettes: Plasmid pIE723 contains the aadB gene cassette precisely inserted at a secondary site in the IncQ plasmid RSF1010.
Mol Microbiol, 15 (1995), pp. 179-187
[12.]
H. Segal, V. Francia, J.M. Garcia Lobo, G. Elisha.
Reconstruction of an active integron recombination site after integration of a gene cassette at a secondary site.
Antimicrob Agents Chemother, 43 (1999), pp. 2538-2541
[13.]
R.M. Hall, D.E. Brookes, H.W. Stokes.
Site-specific insertion of genes into integrons: Role of the 59-base element and determination of the recombination cross.over point.
Mol Microbiol, 5 (1991), pp. 1941-1959
[14.]
R.M. Hall, C.M. Collins.
Mobile gene cassettes and integrons: Capture and spread of genens by site-specific recombination.
Mol Microbiol, 15 (1995), pp. 593-600
[15.]
R.M. Hall, C.M. Collins.
Antibiotic resistance in gram-negative bacteria: The role of gene cassettes and integrons. Drug Resist.
Updates, 1 (1998), pp. 109-119
[16.]
C.M. Collins, R.M. Hall.
Expression of antibiotic resistance genes in the integrated cassettes of integrons.
Antimicrob Agents Chemother, 9 (1995), pp. 165-172
[17.]
R.M. Hall, C.M. Collins, M.J. Kim, S.R. Partridge, G.D. Recchia, H.W. Stokes.
Mobile gene cassettes in evolution.
Ann N Y Acad Sci, 870 (1999), pp. 68-80
[18.]
E. Martínez, F. De la Cruz.
Genetic elements involved in Tn21 site-specific integration, a novel mechanism for the dissemination of antibiotic resistance genes.
EMBO J, 9 (1990), pp. 1275-1281
[19.]
G.D. Recchia, H.W. Stokes, R.M. Hall.
Characterization of specific and secondary recombination sites recognised by the integron DNA integrase.
Nucleic Acids Res, 22 (1994), pp. 2071-2080
[20.]
H.W. Stokes, D.B. O’Gorman, G.D. Recchia, M. Parsekhian, M. Hall.
Structure and function of 59-base element recombination sites associated with mobile gene cassettes.
Mol Microbiol, 26 (1997), pp. 731-745
[21.]
K. Hansson, O. Sköld, L. Sundström.
Non-palindromic attI sites of integrons are capable of site-specific recombination with one another and with secondary targets.
Mol Microbiol, 26 (1997), pp. 441-453
[22.]
Recchia GD. Mobile gene cassettes and integrons: Evolutionary and recombinational studies. 1996. PhD thesis, Macquarie University Sydney, Australia
[23.]
M.V. Francia, P. Avila, F. De la Cruz, M. Garcia Lobo.
A hot spot in plasmid F for site-specific recombination mediated by Tn21 integron integrase.
J Bacteriol, 179 (1997), pp. 4419-4425
[24.]
S.R. Partridge, H.J. Brown, H.W. Stokes, R.M. Hall.
Transposons Tn1696 and Tn21 and their integrons In4 and In2 have independent origins.
Antimicrob Agents Chemother, 45 (2001), pp. 1263-1270
[25.]
Y. Arakawa, M. Murakami, K. Suzuki, H. Ito, R. Wacharotayankun, S. Ohsuka, et al.
A novel integron-like element carrying the metallo-beta-lactamase gene blaIMP.
Antimicrob Agents Chemother, 39 (1995), pp. 1612-1615
[26.]
C. Verdet, G. Arlet, G. Barnaud, P.H. Lagrange, A. Philippon.
A novel integron in Salmonella enterica serovar Enteritidis, carrying the blaDHA-1 gene and its regulator gene ampR, originated from Morganella morganii.
Antimicrob Agents Chemother, 44 (2000), pp. 222-225
[27.]
D. Mazel, B. Dychinco, V. Webb, J. Davies.
A distinctive class of integron in the Vibrio cholerae genome.
Science, 280 (1998), pp. 605-608
[28.]
S.R. Partridge, G.D. Recchia, C. Scaramuzzi, C.M. Collis, H.W. Stokes, R.M. Hall.
Definition of the attI1 site of class 1 integrons.
Microbiology, 146 (2000), pp. 2855-2864
[29.]
C.A. Clark, L. Purins, P. Kaewrakon, T. Focareta, P.A. Manning.
2000. The Vibrio cholerae O1 chromosomal integron.
Microbiology, 146 (1995), pp. 2605-2612
[30.]
B.S. Nield, A.J. Holmes, M.R. Gillings, G.D. Recchia, B.C. Mabbutt, K.M. Nevalainen, et al.
Recovery of new integron classes from environmental DNA.
FEMS Microbiol Lett, 195 (2001), pp. 59-65
[31.]
B. Hochhut, Y. Lotfi, D. Mazel, S.M. Faruque, R. Woodgate, M.K. Waldor.
Molecular analysis of antibiotic resistance gene clusters in Vibrio cholerae O139 and O1 SXT constins.
Antimicrob Agents Chemother, 45 (2001), pp. 2991-3000
[32.]
R.M. Hall, H.J. Brown, D.E. Brookes, H.W. Stokes.
Integrons found in different locations have identical 5’ ends but variable 3’ ends.
J Bacteriol, 176 (1994), pp. 6286-6294
[33.]
K. Senda, Y. Arakawa, S. Ichiyama, K. Nakashima, H. Ito, S. Ohsuka, et al.
PCR detection of metallo-beta-lactamase gene bla(IMP) in gram-negative rods resistant to broad-spectrum beta-lactams.
J Clin Microbiol, 34 (1996), pp. 2909-2913
[34.]
H.J. Brown, H.W. Stokes, R.M. Hall.
The integrons In0, In2, and In5 are defective transposon derivates.
J Bacteriol, 178 (1996), pp. 4429-4437
[35.]
L. Sundström, G. Swedberg, O. Skold.
Characterization of transposon Tn5086, carrying the site-specifically inserted gene dhfrVII mediating trimethoprim resistance.
J Bacteriol, 175 (1993), pp. 1796-1805
[36.]
R.M. Hall, H.W. Stokes.
Integrons: Novel DNA elements which capture genes by site-specific recombination.
Genetica, 90 (1993), pp. 115-132
[37.]
E. Tietze, J. Brevet, H. Tschape.
Relationships among the streptothricin resistance transposons Tn1825 and Tn1826 and the trimethoprim resistance transposon Tn7.
Plasmid, 18 (1987), pp. 246-249
[38.]
H.K. Young, M.J. Qumsieh, M.L. McIntosh.
Nucleotide sequence and genetic analysis of the type Ib trimethoprim-resistant, Tn4132-encoded dihydrofolate reductase.
J Antimicrob Chemother, 34 (1994), pp. 715-725
[39.]
L. Sundström, P.H. Roy, O. Sköld.
Site-specific insertion of three structural gene cassettes in transposon Tn7.
J Bacteriol, 173 (1991), pp. 3025-3028
[40.]
M.C. Ploy, F. Denis, P. Courvalin, T. Lambert.
Molecular characterization of integrons in Acinetobacter baumannii: description of a hybrid class 2 integron.
Antimicrob Agents Chemother, 44 (2000), pp. 2684-2688
[41.]
N. Laraki, M. Galleni, I. Thamm, M.L. Riccio, G. Amicosante, J.M. Frere, et al.
Structure of In31, a bla(IMP)-containing Pseudomonas aeruginosa integrons phyletically related to In5, which carries an unusual array of genes cassettes.
Antimicrob Agents Chemother, 43 (1999), pp. 890-901
[42.]
D.A. Rowe-Magnus, D. Mazel.
Integrons: Natural tools for bacterial genome evolution.
Curr Opin Microbiol, 4 (2001), pp. 565-569
[43.]
J.F. Heidelberg, J.A. Eisen, W.C. Nelson, R.A. Clayton, M.L. Gwinn, R.J. Dodson, et al.
DNA sequence of both chromosomes of the cholera pathogen Vibrio choleare.
Nature, 406 (2000), pp. 477-483
[44.]
C.M. Collins, G.D. Recchia, M.J. Kim, H.W. Stokes, R.M. Hall.
Efficiency of recombination reactions catalyzed by Class 1 integron integrase IntI1.
J Bacteriol, 183 (2001), pp. 2535-2542
Copyright © 2002. Elsevier España, S.L.. Todos los derechos reservados
Opciones de artículo
Herramientas
es en pt

¿Es usted profesional sanitario apto para prescribir o dispensar medicamentos?

Are you a health professional able to prescribe or dispense drugs?

Você é um profissional de saúde habilitado a prescrever ou dispensar medicamentos