Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 27
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Biochemistry (Mosc) ; 76(1): 36-48, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21568838

RESUMO

Fanconi anemia (FA) is an autosomal disorder that causes genome instability. FA patients suffer developmental abnormalities, early-onset bone marrow failure, and a predisposition to cancer. The disease is manifested by defects in DNA repair, hypersensitivity to DNA crosslinking agents, and a high degree of chromosomal aberrations. The FA pathway comprises 13 disease-causing genes involved in maintaining genomic stability. The fast pace of study of the novel DNA damage network has led to the constant discovery of new FA-like genes involved in the pathway that when mutated lead to similar disorders. A majority of the FA proteins act as signal transducers and scaffolding proteins to employ other pathways to repair DNA. This review discusses what is known about the FA proteins and other recently linked FA-like proteins. The goal is to clarify how the proteins work together to carry out interstrand crosslink repair and homologous recombination-mediated repair of damaged DNA.


Assuntos
Dano ao DNA , Reparo do DNA , Anemia de Fanconi/genética , Animais , Anemia de Fanconi/metabolismo , Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Proteínas de Grupos de Complementação da Anemia de Fanconi/metabolismo , Humanos
2.
FEBS Lett ; 258(2): 244-6, 1989 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-2599091

RESUMO

It was found that DNA alkylation at the N-7 guanine with the bulky alkylating reagent, N,N,N'-tri-(beta-chloroethyl)-N'-(p-formylphenyl)propylene diamine-1,3 (TFP) is much diminished when DNA is double-stranded. We report here an application of this reaction for probing the hairpin structure in the palindrome-containing single-stranded (ss) DNA fragment of 377 bases prepared from the Eco-RI-BaMHI fragment of plasmid pBR322. 5'-Labeled ss fragment was modified with TFP and cleaved by piperidine hydrolysis at the alkylated guanine residues according to the Maxam-Gilbert procedure. Guanines in the hairpin formed by palindrome of 9 bp were protected from TFP action, while dimethyl sulfate modified all guanines.


Assuntos
DNA de Cadeia Simples , DNA , Conformação de Ácido Nucleico , Alquilantes , Sequência de Bases , DNA Bacteriano , DNA Viral , Dados de Sequência Molecular , Compostos de Mostarda Nitrogenada , Desnaturação de Ácido Nucleico , Plasmídeos
3.
DNA Cell Biol ; 9(1): 63-9, 1990.
Artigo em Inglês | MEDLINE | ID: mdl-2317271

RESUMO

A new site-directed method for inserting long single-stranded DNA fragments into any region of a duplex vector is described. Its major advantage is independence of the location of the restriction sites. The method involves the assembly of single-stranded DNA fragments by ligation to both ends of the inserted fragments of two cohesive flanks that are complementary to the target region. Short oligonucleotide templates are used to direct the ligation. The resulting fragments, designated further as omega fragments with cohesive flanks, are hybridized with a gapped DNA vector. The heteroduplexes are transformed into Escherichia coli cells without enzymatic filling and sealing of gapped DNA. As a consequence of intracellular repair and heteroduplex resolution, insertion mutants are recovered. To demonstrate the method's efficiency, we inserted a 51-nucleotide synthetic DNA fragment containing a modified glucocorticoid receptor binding site into the region of pBR322, near the transcription starting point of the tet gene. The method we developed makes possible site-directed insertion of synthetic and genome-derived DNA fragments at least 200 nucleotides long.


Assuntos
DNA de Cadeia Simples/genética , Engenharia Genética/métodos , Sequência de Bases , Reparo do DNA , Dados de Sequência Molecular , Mutação , Ácidos Nucleicos Heteroduplexes/metabolismo , Plasmídeos , Receptores de Glucocorticoides/genética , Recombinação Genética , Transfecção
4.
Mutat Res ; 249(1): 189-93, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1829790

RESUMO

The role of different DNA damages in the stimulation of homologous recombination was studied by using an in vivo plasmid recombination assay. Dimethyl sulphate (DMS) treatment of plasmid DNA induced a 20-50-fold increase in the frequency of recombinational events. DMS treatment also stimulated RecA protein binding to double-stranded DNA. In contrast, plasmid DNA containing uracil, which, like DMS, is also subject to repair, was less effective in stimulation of recombination. The ability of purified RecA protein to bind DMS-treated or uracil-containing DNA was tested by measuring its ATPase activity. The result indicates that DMS treatment, but not uracil incorporation, stimulates RecA protein binding to DNA. We conclude, that the main reason (or the first step) for stimulation of recombination by mutagens is activation of RecA binding to damaged DNA.


Assuntos
DNA Bacteriano , DNA Bacteriano/genética , Mutagênicos , Ácidos Nucleicos Heteroduplexes/metabolismo , Plasmídeos , Recombinases Rec A/metabolismo , Recombinação Genética , Ésteres do Ácido Sulfúrico/toxicidade , Adenosina Trifosfatases/metabolismo , Dano ao DNA , Reparo do DNA , DNA Bacteriano/metabolismo , Escherichia coli/metabolismo , Uracila/metabolismo
5.
Mol Biol (Mosk) ; 15(1): 252-6, 1981.
Artigo em Russo | MEDLINE | ID: mdl-7335077

RESUMO

To affect definite preselected regions of DNA, complementary denaturated DNA fragments carrying alkylating groups were used. The residues of polyfunctional alkylating agent N',N'N'-tri(beta-chloroethyl)-N'-(p-formylphenyl)propylenediamine-1,3 were attached covalently to 4-5% of bases of the T7 phage DNA (T7 DNA) restriction fragment. The alkylating DNA derivatives was found to be stable under hybridisation conditions. It was shown that the DNA fragment carrying alkylating groups is capable of highly specific interaction with complementary DNA. Thus, the alkylating derivative of the T7 DNA restriction fragment retains its capacity to hybridise with T7 DNA, however, it does not interact with the noncomplementary DNA from chick erythrocytes, it was established that the alkylating derivative of DNA fragment efficiently alkylates only the complementary DNA.


Assuntos
Alquilantes , DNA Viral/metabolismo , DNA/metabolismo , Compostos de Mostarda Nitrogenada , Animais , Galinhas , Estabilidade de Medicamentos , Eritrócitos/metabolismo , Genes , Genes Virais , Hibridização de Ácido Nucleico
6.
Mol Biol (Mosk) ; 26(1): 93-103, 1992.
Artigo em Russo | MEDLINE | ID: mdl-1508174

RESUMO

We present a computer system "DIROM" for oligonucleotide-directed mutagenesis and artificial gene design experiments planning and support. "DIROM" allows to search for optimal oligonucleotides according to such parameters as sufficient energy of oligonucleotide-target hybridization, secondary structure of oligonucleotide and target DNA, presence of alternative attachment sites in target DNA, terminal G/C pairs presence. Both single-stranded and double-stranded vector mutagenesis methods are implemented. It can be also used for optimal primer selection for polymerase chain reaction, sequencing etc. "DIROM" can search for both existent and potential carry out vector+target sequence construction. Both amino acid and nucleotide sequences can be operated.


Assuntos
Genes Sintéticos , Mutagênese Sítio-Dirigida , Software , Sequência de Aminoácidos , Sequência de Bases , Dados de Sequência Molecular , Hibridização de Ácido Nucleico
7.
Mol Biol (Mosk) ; 14(2): 261-4, 1980.
Artigo em Russo | MEDLINE | ID: mdl-7383025

RESUMO

For addressed modification of T7 phage DNA a polyalkylating derivative of T7 phage early transcript was used. The derivative was obtained by attaching polyfunctional alkylating agent N,N,N,'-tri(beta-chloroethyl)-N'-(p-formylphenyl) propylene diamine-1,3 to the transcript, their molecules being covalently bound by alkylating 4--5% of the RNA adenine and guanine residues. The polyalkylating RNA was used to form R-loops in the complementary site of T7 DNA to alkylate selectively the T7 phage early DNA. Alkylation of DNA by the modified transcript in the region of the R-loop led to the covalent binding of the transcript to the complementary site of DNA. The correct localization of this R-loop was confirmed by electron microscopy. The application of the results for the addressed mutagenesis and inactivation of selected genes is discussed.


Assuntos
DNA Viral , Hibridização de Ácido Nucleico , Fagos T/genética , Alquilação , Diaminas , Desnaturação de Ácido Nucleico , Transcrição Gênica
8.
Mol Biol (Mosk) ; 18(4): 1081-9, 1984.
Artigo em Russo | MEDLINE | ID: mdl-6095023

RESUMO

A method is suggested for chemical modification of preselected regions of plasmid DNA by complementary single-stranded restriction fragments of DNA (srf DNA), carrying alkylating reagents. The gene coding for tetracycline resistance of plasmid pBR322 was used as a target. Srf DNA was prepared by a partial digestion of a double-stranded EcoRI-BamHI restriction fragment (377 base pairs) from Tcr by E. coli exonuclease III. The residues of an alkylating reagent N,N,N'-tri(beta-chlorethyl)-N'-(p-formylphenyl) propylenediamine 1,3 (TFP) were attached covalently to 4-5% of sfr DNA bases. The alkylating derivative of the sfr DNA was hybridized with supercoiled pBR322 plasmid DNA. The hybridization conditions (37 degrees C, 40% formamide, 0,2 M NaCl, 0,1 M Tris-HCl pH 7,5, 0,001 M EDTA) under which the bases carrying TFP residues are not eliminated from the sfr DNA, and transforming activity of pBR322 DNA does not decrease were established. It was shown that about 20% of plasmid pBR322 molecules form D-loops with alkylating sfr DNA under these conditions. It was shown that sfr DNA, carrying TFP can alkylate the complementary region of plasmid DNA, forming cross-linked D-loops. A method for the site-directed mutagenesis of switching off the preselected genes or non-transcribed DNA functional regions (promotors, introns etc) integrated into plasmids of other vectors is suggested.


Assuntos
DNA Bacteriano/genética , Escherichia coli/genética , Genes Bacterianos , Plasmídeos , Alquilação , Cromatografia de Afinidade , DNA/genética , Enzimas de Restrição do DNA , DNA de Cadeia Simples/genética , Hidrólise , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico
9.
Bioorg Khim ; 11(12): 1690-2, 1985 Dec.
Artigo em Russo | MEDLINE | ID: mdl-3002395

RESUMO

A new method of discrimination of double-stranded (ds) and single-stranded (ss) regions in DNA molecules has been developed. It makes use of two alkylating reagents, a voluminous and a small-sized, the former being sensitive to the DNA conformation. A bulky reagent, N,N,N'-tri(beta-chloroethyl)-N'-(p-formylphenyl) propylendiamine-1,3 (TFP), was used to detect the hairpin structure in the palindrome-containing DNA fragment 373 nucleotides long prepared from the ds EcoRI-BamHI fragment of the plasmid pBR322. The fragment was modified by TFP and cleaved by piperidine at the alkylated guanine residues according to the Maxam-Gilbert procedure. Guanine residues in the hairpin formed by palindrome were protected from the TFP action, while dimethylsulfate modified all guanines. Application of the method for the identification of loops, stem-and-loop structures, and unwinded regions of DNA is discussed.


Assuntos
DNA/análise , Conformação de Ácido Nucleico , Alquilação , Sequência de Bases , Enzimas de Restrição do DNA , DNA de Cadeia Simples/análise , Cinética
10.
Mol Gen Mikrobiol Virusol ; (2): 12-6, 1988 Feb.
Artigo em Russo | MEDLINE | ID: mdl-2836723

RESUMO

A new method for obtaining the recombinant DNA based on heteroduplex-initiated site-directed insertion of alien nucleotide sequences is proposed. To generate a single-stranded region, plasmid DNA was nicked with restriction endonuclease in the presence of ethidium bromide with subsequent exonuclease III controlled digestion. The inserted DNA sequences flanked by nucleotide sequences complementary to single-stranded region were annealed with plasmid DNA and E. coli cells were transformed by the resulting heteroduplex molecules. The presented data show the possibility to insert as many as 200 nucleotides. The yield of recombinant DNA varied from 16 to 0.7% as the number of nucleotides inserted correspondingly varied from 15 to 200. The site of insertion does not depend crucially on the localization of the restriction site used.


Assuntos
DNA Recombinante , Ácidos Nucleicos Heteroduplexes , Hibridização de Ácido Nucleico , Plasmídeos , Sequência de Bases , Clonagem Molecular , Enzimas de Restrição do DNA , Escherichia coli/genética
11.
Genetika ; 22(10): 2398-407, 1986 Oct.
Artigo em Russo | MEDLINE | ID: mdl-3025061

RESUMO

This study is concerned with an experimental verification of hypotheses postulating the involvement of self-complementary nucleotide sequences in the formation of deletions and insertions. It was suggested that deletions can arise in the regions of self-complementary nucleotide sequences, which allows the formation of the hairpin structures in a single-stranded DNA, arising during excision repair. These hairpin structures can be eliminated by nucleases or during DNA replication. Insertions can arise as a result of homologous recombination, when a migrating DNA strand contains a self-complementary sequence which forms hairpin structure. Model experiments were carried out with the pBR322 plasmid. A plasmid DNA with premutational damage in the palindrome-containing region was constructed by in vitro dimethylsulfate modification of one strand of EcoRI-BamHI restriction fragment. The plasmid was used for transformation of Escherichia coli. Restriction mapping and nucleotide analysis of the mutant DNAs demonstrated that they all contained deletions. The end points of the deletions coincide with the palindrome. To model homologous recombination, a plasmid with D-loop was constructed. A single-stranded DNA fragment containing palindrome forming a hairpin structure was introduced into the plasmid DNA and covalently fixed in the complex. When E. coli cells were transfected with this DNA, plasmid mutants containing insertions predetermined by palindromic structure arose. The evolutionary role of mutations predetermined by primary DNA structure is discussed.


Assuntos
Sequência de Bases , DNA/genética , Modelos Genéticos , Mutação , Enzimas de Restrição do DNA , DNA Bacteriano/genética , Escherichia coli/genética , Plasmídeos
12.
Genetika ; 27(2): 210-6, 1991 Feb.
Artigo em Russo | MEDLINE | ID: mdl-1874432

RESUMO

Methods for site-directed multiple modification of DNA have been developed and used for modification of either one or two strands of plasmid DNA. Plasmid DNAs modified in the region of the tet gene were transformed into Escherichia coli cells and Tet colonies were screened. It was shown that multiple lesions in one DNA strand performed using either N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or sodium bisulfite were effectively repaired in the cell by error-free mechanism. In contrast, modification of two DNA strands led to induction of mutations. The efficiency of mutagenesis in the case of modification of a local region of one DNA strand with sodium bisulfite and modification of the other strand with MNNG was 1.1-7.9%. Mutations were analysed by restriction mapping and sequencing. All of them were G----A transitions.


Assuntos
Dano ao DNA/genética , Mutagênese Sítio-Dirigida/genética , Mutagênicos/toxicidade , Plasmídeos/genética , Metilnitronitrosoguanidina/toxicidade , Hibridização de Ácido Nucleico , Mapeamento por Restrição , Sulfitos/toxicidade , Transformação Genética/genética
13.
Genetika ; 20(8): 1244-54, 1984 Aug.
Artigo em Russo | MEDLINE | ID: mdl-6386600

RESUMO

In the preselected site of pBR322 plasmid DNA related to the Tcr gene mutations were induced by the complementary single-stranded DNA restricts carrying alkylating groups. The alterations of the DNA primary structure in the mutagenized site were studied. It was found and that in the majority of mutants with the impaired Tcr gene function, the tandem direct repeats appeared. The repeats of 7-8 base pairs were localized in a fixed site of the Tcr gene, downstream of the palindrome. It is suggested that tandem repeats appear as a result of D-loops formation when single-stranded DNA forms a hairpin structure, due to the presence of palindromes. In the light of this notion, the tentative schemes of gene conversion and genome evolution are discussed.


Assuntos
DNA Bacteriano/genética , Escherichia coli/genética , Conversão Gênica , Genes Bacterianos , Sequências Repetitivas de Ácido Nucleico , Sequência de Bases , Evolução Biológica , DNA de Cadeia Simples/genética , Mutação , Plasmídeos , Transformação Bacteriana
15.
Proc Natl Acad Sci U S A ; 93(20): 10673-8, 1996 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-8855238

RESUMO

The RecA protein-single-stranded DNA (ssDNA) filament can bind a second DNA molecule. Binding of ssDNA to this secondary site shows specificity, in that polypyrimidinic DNA binds to the RecA protein-ssDNA filament with higher affinity than polypurinic sequences. The affinity of ssDNA, which is identical in sequence to that bound in the primary site, is not always greater than that of nonhomologous DNA. Moreover, this specificity of DNA binding does not depend on the sequence of the DNA bound to the RecA protein primary site. We conclude that the specificity reflects an intrinsic property of the secondary site of RecA protein rather than an interaction between DNa molecules within nucleoprotein filament--i.e., self-recognition. The secondary DNA binding site displays a higher affinity for ssDNA than for double-stranded DNA, and the binding of ssDNA to the secondary site strongly inhibits DNA strand exchange. We suggest that the secondary binding site has a dual role in DNA strand exchange. During the homology search, it binds double-stranded DNA weakly; upon finding local homology, this site binds, with higher affinity, the ssDNA strand that is displaced during DNA strand exchange. These characteristics facilitate homologous pairing, promote stabilization of the newly formed heteroduplex DNA, and contribute to the directionality of DNA strand exchange.


Assuntos
DNA de Cadeia Simples/metabolismo , DNA/metabolismo , Recombinases Rec A/metabolismo , Recombinação Genética , Desoxirribonucleoproteínas/metabolismo , Escherichia coli , Ligação Proteica , Especificidade por Substrato
16.
EMBO J ; 17(4): 1161-8, 1998 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-9463393

RESUMO

RecA protein features two distinct DNA-binding sites. During DNA strand exchange, the primary site binds to single-stranded DNA (ssDNA), forming the helical RecA nucleoprotein filament. The weaker secondary site binds double-stranded DNA (dsDNA) during the homology search process. Here we demonstrate that this site has a second important function. It binds the ssDNA strand that is displaced from homologous duplex DNA during DNA strand exchange, stabilizing the initial heteroduplex DNA product. Although the high affinity of the secondary site for ssDNA is essential for DNA strand exchange, it renders DNA strand exchange sensitive to an excess of ssDNA which competes with dsDNA for binding. We further demonstrate that single-stranded DNA-binding protein can sequester ssDNA, preventing its binding to the secondary site and thereby assisting at two levels: it averts the inhibition caused by an excess of ssDNA and prevents the reversal of DNA strand exchange by removing the displaced strand from the secondary site.


Assuntos
DNA Bacteriano/metabolismo , DNA Bacteriano/fisiologia , Recombinases Rec A/genética , Recombinases Rec A/metabolismo , Sítios de Ligação/genética , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Nucleoproteínas/metabolismo
17.
Genes Dev ; 13(15): 2005-16, 1999 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-10444598

RESUMO

RecA protein catalyzes DNA strand exchange, a basic step of homologous recombination. Upon binding to single-stranded DNA (ssDNA), RecA protein forms a helical nucleoprotein filament. Normally, this nucleoprotein filament binds double-stranded DNA (dsDNA) and promotes exchange of base pairs between this dsDNA and the homologous ssDNA that is contained within this filament. Here, we demonstrate that this bound dsDNA can be activated by interaction with a heterologous RecA nucleoprotein filament for a novel type of strand exchange with homologous ssDNA that is external to, and, therefore, not within, the filament. We refer to this novel DNA strand exchange as being in trans. Thus, the RecA nucleoprotein filament is a protein scaffold that activates dsDNA for strand exchange with ssDNA either within the filament or external to it. This new property demonstrates that the RecA nucleoprotein filament makes dsDNA receptive for DNA strand exchange, and it defines an early step of the homology recognition mechanism.


Assuntos
DNA/metabolismo , Escherichia coli/genética , Recombinases Rec A/metabolismo , Recombinação Genética/genética , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/metabolismo , Pareamento de Bases , Sequência de Bases , Ligação Competitiva , DNA/genética , DNA de Cadeia Simples/genética , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Eletroforese em Gel de Poliacrilamida , Escherichia coli/metabolismo , Cinética , Modelos Genéticos , Mutação , Ácidos Nucleicos Heteroduplexes/genética , Hibridização de Ácido Nucleico , Ligação Proteica , Recombinases Rec A/genética , Homologia de Sequência do Ácido Nucleico , Temperatura
18.
Comput Appl Biosci ; 8(5): 425-31, 1992 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1422875

RESUMO

A computer system DIROM for oligonucleotide-directed mutagenesis and artificial gene design has been designed for better experimental planning and control. DIROM permits searching for optimal oligonucleotides with respect to certain important parameters, namely sufficient energy of oligonucleotide-target hybridization, the secondary structure of oligonucleotide and target DNA, the presence of alternate binding sites in the target DNA and terminal G/C pairs. It can also be used to plan polymerase chain reaction experiments, for optimal primer selection, in sequencing, etc. DIROM enables one to search for both existing and potential restriction sites, to perform vector + target sequence construction. The system consists of a set of original algorithms that formalize the empirical knowledge of oligonucleotide action as primers.


Assuntos
Engenharia Genética , Biologia Molecular/instrumentação , Mutagênese Sítio-Dirigida , Software , Algoritmos , Sequência de Bases , Dados de Sequência Molecular , Design de Software , Interface Usuário-Computador
19.
Mol Gen Genet ; 228(1-2): 153-9, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1679524

RESUMO

Derivatives of plasmid pBR327 with the tet gene interrupted by 165 pb or 401 bp direct repeats were constructed. In cells harboring these plasmids, deletions which restored the wild-type tet gene gave rise to tetracycline-resistant colonies, thereby allowing a simple phenotypic test for deletion formation. The frequencies of deletions in these plasmids were measured in Escherichia coli strains proficient or deficient in general recombination. The structure of plasmid DNA isolated from tetracycline-resistant transformants was analyzed by agarose gel electrophoresis, restriction mapping and sequencing. The data presented here demonstrate that deletion formation is always associated with dimerization of plasmid DNA. Dimeric plasmids were of two types. Those which carried both a deletion and a compensating duplication were the major type in a Rec+ background and were rare in recA, recF, recJ and recO backgrounds. Dimers of the second type contained deletions, but no compensating duplications, and their formation was RecA-independent. The data presented demonstrate that deletion formation mediated by long direct repeats is mainly the result of unequal crossing-over between two plasmid molecules.


Assuntos
Escherichia coli/genética , Mutação , Plasmídeos/genética , Mapeamento Cromossômico , Resistência Microbiana a Medicamentos/genética , Eletroforese em Gel de Ágar , Frequência do Gene , Família Multigênica , Polimorfismo de Fragmento de Restrição , Recombinação Genética , Proteínas Repressoras/genética , Tetraciclina
20.
Mol Gen Genet ; 228(1-2): 209-14, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1679526

RESUMO

A set of plasmids containing 42, 21 and 31 bp direct repeats was used to analyze the effect of repeat length on the frequencies of deletion formation and the structure of the deleted derivatives of different recombination-deficient Escherichia coli strains. Agarose gel electrophoresis of plasmid DNA demonstrated that the formation of deletions in these plasmids was associated with dimerization of plasmid DNA. Restriction analysis of the dimers showed that deletions at short direct repeats arose non-conservatively, that is, the formation of a deletion in one monomeric plasmid unit was not associated with a duplication in the other. Mutations in the recA, recF, recJ and recO genes had no marked effect on either the frequencies of deletion formation or the structure of dimers. In contrast, recB recC mutations greatly increased the frequencies of deletion formation, 6-fold for 42 bp, and 115-fold for 21 bp direct repeats. Conversion of DNA replication to the rolling circle mode in a recB recC strain, resulting in the formation of double-stranded ends, is suggested as the stimulatory effector.


Assuntos
Escherichia coli/genética , Genes Bacterianos , Família Multigênica , Mutação , Plasmídeos/genética , Eletroforese em Gel de Ágar , Polimorfismo de Fragmento de Restrição , Mapeamento por Restrição
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA