Properties of Acinetobacter calcoaceticus recA and its contribution to intracellular gene conversion

La, Gregg-Jolly; Ln, Ornston

doi:10.1111/j.1365-2958.1994.tb01086.x

Cited by 35 publications

(35 citation statements)

References 28 publications

(16 reference statements)

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“…In agreement with this, it was recently observed that the upstream sequence of the A. calcoaceticzls recA gene is not preceded by a LexA-binding motif (Gregg-Jolly & Ornston, 1994). The promoter regions of the recA genes of T.ferrooxidans (Ramesar etal., 1989), N .…”

Section: Discussionsupporting

confidence: 56%

The expression of the Acinetobacter calcoaceticus recA gene increases in response to DNA damage independently of RecA and of development of competence for natural transformation

Rauch¹,

Palmen²,

Burds

et al. 1996

Microbiology

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Using the lacZ operon fusion technique, the transcriptional control of the Acinetobacter calcoaceticus r e d gene was studied. A low (approximately twofold) inductive capacity was observed for compounds that damage DNA and/or inhibit DNA replication, e.g. methyl methanesulfonate, mitomycin C, UV light and nalidixic acid. Induction of the r e d gene by DNA damage was independent of functional RecA. The presence of the r e d promoter region on a multicopy plasmid had the same effect on r e d transcription as the presence of DNA-damaging agents. Thus, r e d expression in A. calcoaceticus appears to be regulated in a novel fashion, possibly involving a non-Lea-like repressor. Regulation of the r e d gene in A. calcoaceticus appears not to be part of a regulon responsible for competence for natural transformation : in cells exhibiting extremely low transformation frequencies, the level of transcription of the r e d gene was found to be comparable to the level found in cells in the state of maximal competence.

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Section: Discussionsupporting

confidence: 56%

The expression of the Acinetobacter calcoaceticus recA gene increases in response to DNA damage independently of RecA and of development of competence for natural transformation

Rauch¹,

Palmen²,

Burds

et al. 1996

Microbiology

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“…The lack of a LexA protein has also been previously reported in Bacillus fragilis (17), Thiobacillus ferrooxidans (35), Porphyromonas gingivalis (12), and Acinetobacter calcoaceticus (18). In radiation-resistant Deinococcus radiodurans LexA is present, but cleavage is not enhanced by recA expression (30 (Fig.…”

Section: Discussionmentioning

confidence: 66%

Functional Properties ofBorrelia burgdorferi recA

Liveris¹,

Mulay²,

Schwartz

2004

J Bacteriol

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Functions of the Borrelia burgdorferi RecA protein were investigated in Escherichia coli recA null mutants. Complementation with B. burgdorferi recA increased survival of E. coli recA mutants by 3 orders of magnitude at a UV dose of 2,000 J/cm 2 . The viability at this UV dose was about 10% that provided by the homologous recA gene. Expression of B. burgdorferi recA resulted in survival of E. coli at levels of mitomycin C that were lethal to noncomplemented hosts. B. burgdorferi RecA was as effective as E. coli RecA in mediating homologous recombination in E. coli. Furthermore, E. coli phage lysogens complemented with B. burgdorferi recA produced phage even in the absence of UV irradiation. The level of phage induction was 55-fold higher than the level in cells complemented with the homologous recA gene, suggesting that B. burgdorferi RecA may possess an enhanced coprotease activity. This study indicates that B. burgdorferi RecA mediates the same functions in E. coli as the homologous E. coli protein mediates. However, the rapid loss of viability and the absence of induction in recA expression after UV irradiation in B. burgdorferi suggest that recA is not involved in the repair of UV-induced damage in B. burgdorferi. The primary role of RecA in B. burgdorferi is likely to be a role in some aspect of recombination.The spirochete Borrelia burgdorferi, the causative agent of Lyme disease, has a unique genomic organization consisting of a 910,725-bp linear chromosome and at least 21 linear and circular plasmids (6, 13). Less than one-half of the 1,689 annotated open reading frames have an identifiable database match (6, 13). In addition, very few genes have been characterized biochemically. Functional studies of B. burgdorferi genes in the postgenomic era have been hampered by this spirochete's slow growth in culture and by the limited availability of genetic tools. A potentially useful strategy for circumventing these difficulties is complementation of mutants in well-characterized bacteria, such as Escherichia coli. This strategy has been employed to elucidate the functions of a number of B. burgdorferi gene products (1,5,7,8,15,20,26,32,44,49,50).Genetic recombination may play a role in B. burgdorferi persistence by generation of antigenic variation (2,31,37,45,47,52,56,57). RecA is the key protein linking genetic recombination to DNA replication and repair in bacteria (23,24). In E. coli, RecA promotes pairing and strand exchange between a single-stranded DNA molecule and a homologous doublestranded DNA molecule through a complex multistep pathway that requires a DNA-dependent ATPase function (29). In addition to this recombinase activity, an ATP-dependent coprotease activity has also been ascribed to RecA. In enterobacteria and Bacillus sp., the latter activity is part of a specialized and regulated form of DNA repair designated SOS repair (3). In E. coli, the SOS response involves the transcriptional repressor LexA, whose autocatalytic cleavage is enhanced by activated RecA following DNA damage (19). This res...

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“…Conversion is less common in bacteria, where the DNA is mostly unique, but it occurs between the rrn operons, which are members of a multigene family (9,10). In addition, conversion of the Salmonella phase 1 flagellin gene fliC to the phase 2 gene fliB in E. coli has been demonstrated (24), and the catIJF and pcaIJF genes of Acinetobacter calcoaceticus, which have nearly identical nucleotide sequences, convert each other in a recA-dependent process at rates of about 10 Ϫ6 (8,16). The following points support the hypothesis that dispersion and sequence maintenance of IVSs is due to gene conversion.…”

Section: Discussionmentioning

confidence: 99%

Salmonella typhimurium LT2 possesses three distinct 23S rRNA intervening sequences

Mattatall¹,

Sanderson²

1996

J Bacteriol

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The rrl genes for 23S rRNA of Salmonella typhimurium LT2 are known to carry intervening sequences (IVSs) at two sites, helix-25 and helix-45, which are excised by RNase III during rRNA maturation, resulting in rRNA which is fragmented but nevertheless functional. We isolated DNA fragments containing the seven rrl genes from BlnI, I-CeuI, and SpeI genomic digests following pulsed-field gel electrophoresis and used these DNA fragments as templates for PCRs utilizing primers upstream and downstream of helix-25 and helix-45. Variance in amplicon length and cycle sequencing indicated that rrlG and rrlH have IVSs in helix-25 of ϳ110 bp which are only 56% identical. rrnA, rrnB, rrnC, rrnD, rrnE, and rrnH have IVSs of ϳ90 bp in helix-45, and all have the same nucleotide sequence. Twenty-one independent wild-type strains of S. typhimurium from Salmonella Reference Collection A were analyzed for IVSs by using PCRs with genomic DNAs and by denaturing agarose electrophoresis of RNAs. Many strains resemble LT2, but some have no IVSs in helix-25 and others have IVSs in helix-45 in all seven rrl genes. However, the IVSs in individual wild-type lines are relatively stable, for several LT2 isolates separated over many years by many single-colony isolations are indistinguishable from one another, with the exception of line LB5010, which differs by one helix-25 IVS. We postulate that IVSs have entered strain LT2 by three independent lateral-transfer events and that the IVS in helix-45 was dispersed to and maintained in the same sequence in six of the seven rrl genes by the mechanism of gene conversion.The prokaryotic 50S ribosomal subunit contains contiguous 23S and 5S rRNAs; in certain genera of bacteria, such as Campylobacter (14,19,32), Leptospira (11,25,26), Rhodobacter (15, 17), Salmonella (4,12,13,29,30,33), and Yersinia (29), the 23S rRNA can be fragmented into two or more pieces. In Salmonella typhimurium LT2, 23S rRNA fragmentation is caused by RNase III excision (without repair) of novel intervening sequences (IVSs) of ϳ90 to 110 bp (4). Most IVSs do not contain open reading frames or terminal consensus sequences to facilitate any other type of excision or mobilization. For this reason, IVSs are not true introns but are related elements that disrupt the normal continuity of a gene without affecting its function. The 23S rRNA fragments maintain functionality, presumably through secondary structure and ribosomal protein interactions in the 50S subunit.S. typhimurium possesses two distinct types of IVSs, on the basis of rRNA fragment stoichiometry (4), one at about bp 550 and another at about bp 1170 in the rrl gene (for the 23S rRNA) (Escherichia coli gene numbering [23]). These positions correspond to helix-25 and helix-45 in the postulated secondary structure of the 23S rRNA of E. coli; both of these helices represent small tetraloops. IVSs partly replace these small helices with an extended helix and loop. Sequencing of two helix-45 IVSs isolated from two independent strains of S. typhimurium, ATCC 23566 (4) and 13311 (...

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Properties of Acinetobacter calcoaceticus recA and its contribution to intracellular gene conversion

Cited by 35 publications

References 28 publications

The expression of the Acinetobacter calcoaceticus recA gene increases in response to DNA damage independently of RecA and of development of competence for natural transformation

The expression of the Acinetobacter calcoaceticus recA gene increases in response to DNA damage independently of RecA and of development of competence for natural transformation

Functional Properties ofBorrelia burgdorferi recA

Salmonella typhimurium LT2 possesses three distinct 23S rRNA intervening sequences

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