IST1 insertional inactivation of the resB gene: implications for phenotypic switching in Thiobacillus ferrooxidans

Cabrejos, M María Eugenia

doi:10.1016/s0378-1097(99)00193-7

Cited by 9 publications

(11 citation statements)

References 12 publications

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“…The identification of the petI and res operons also supports a model for phenotypic switching (10) in which the reversible insertion of ISAfe1 (formerly IST1) into resB results in a mutant phenotype in which cells are unable to utilize Fe(II) as a sole energy and electron source but can still grow in the presence of reduced sulfur (2,16). Insertional inactivation of resB by ISAfe1 could lead to an incorrectly matured cytochrome c, possibly the diheme cytochrome c 4 and/or the cytochrome c 1 encoded by the petI operon, effectively knocking out uphill electron flow through complex III.…”

Section: Fig 1 Map Of the Peti And Res Operons Of A Ferrooxidansmentioning

confidence: 55%

“…The deduced characteristics of the proteins encoded by the petI operon are summarized in Table 1. Deduced characteristics of the proteins encoded by the res operon have already been described (2). It is reasonable to propose that putative cytochrome c 1 , Rieske protein, and cytochrome b form part of a membrane-associated complex III electron transport system.…”

Section: Fig 1 Map Of the Peti And Res Operons Of A Ferrooxidansmentioning

confidence: 93%

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Characterization of the petI and res Operons of Acidithiobacillus ferrooxidans

Levicán¹,

Bruscella

Guacunano³

et al. 2002

J Bacteriol

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DNA sequence analysis and bioinformatic interpretations have identified two adjacent clusters of genes potentially involved in the formation of a bc1 complex and in the maturation of a cytochrome c-type protein in two strains (ATCC 19859 and ATCC 33020) of the acidophilic, chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans (formerly Thiobacillus ferrooxidans). Reverse transcriptase-PCR experiments suggest that the two clusters are organized as operons, and ؉1 start sites of transcription for the operons have been determined by primer extension experiments. Potential promoters have been identified. The presence of these operons lends support to a recent model of reverse electron flow and is consistent with previous reports of phenotypic switching in this bacterium.Acidithiobacillus ferrooxidans, formerly Thiobacillus ferrooxidans (13), is a chemolithoautotrophic gram-negative bacterium that derives energy and electrons from the oxidation of ferrous iron and/or sulfur and various reduced sulfur compounds at pH 2 by using oxygen as the electron acceptor (11). It fixes CO 2 by the Calvin-Bassham-Benson scheme and can also fix nitrogen under microaerophilic conditions. A. ferrooxidans has been reported to be able to grow on hydrogen as an energy source both aerobically (4) and anaerobically by the dissimilatory reduction of Fe(III) (14). It has been shown to be active in the solubilization of copper and in the processing of refractory gold ores in bioleaching operations and is also a contributor to acid mine drainage.An intriguing problem is how A. ferrooxidans can generate the reduced pyridine nucleotides NADH and NADPH when using Fe(II) as the sole source of electrons and energy. The problem is that the standard reduction half-potential of the Fe 2ϩ /Fe 3ϩ couple (pH 2) is ϩ0.77 V while that of the NAD ϩ / NADH couple (pH 7) is Ϫ0.32 V. Therefore, to generate NADH, it is necessary to "push" electrons "uphill" from Fe(II) to NAD ϩ against a thermodynamically favorable gradient. It has been speculated that the energy required for this uphill electron flow could come primarily from the proton motive force resulting from an influx of protons across the A. ferrooxidans membrane since the exterior pH of the medium is 2 and that of the interior of the cell is 6.5 (12). It was further speculated that the pathway that the electrons take during uphill flow is from Fe(II) via a bc1 complex and a membranesoluble quinone to a NAD ϩ reductase complex (12). A downhill pathway of electrons in A. ferrooxidans has been described; in this pathway electrons derived from the oxidation of Fe(II) reduce oxygen to water via a series of electron carriers that remain inconclusively identified but that may include an outer membrane cytochrome (19), an iron-sulfur protein, blue copper protein rusticyanin, a cytochrome c 4 , and a terminal cytochrome aa 3 oxidase (1). This is considered the downhill pathway because electrons flow from the reduction potential of Fe 2ϩ (ϩ0.77 V) to the more positive reduction potential of O 2 , which...

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Section: Fig 1 Map Of the Peti And Res Operons Of A Ferrooxidansmentioning

confidence: 55%

Section: Fig 1 Map Of the Peti And Res Operons Of A Ferrooxidansmentioning

confidence: 93%

Characterization of the petI and res Operons of Acidithiobacillus ferrooxidans

Levicán¹,

Bruscella

Guacunano³

et al. 2002

J Bacteriol

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“…Genetic evidence has been presented for the existence of a cytochrome-containing complex functioning exclusively during iron oxidation (Cabrejos et al, 1999;Levicán et al, 2002) and it has been reported that a bc 1 complex functions only in reverse in iron-grown cells (Elbehti et al, 2000), even in the presence of an appropriate substrate (Brasseur et al, 2002). On the other hand the existence of a bc 1 complex has been proposed to be involved in the aerobic and anaerobic oxidation of sulfur and formate processes (Corbett & Ingledew, 1987;Pronk et al, 1991) and a bc 1 complex has been shown recently to function in direct mode in sulfur-grown cells (Brasseur et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Differential expression of two bc 1 complexes in the strict acidophilic chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans suggests a model for their respective roles in iron or sulfur oxidation

et al. 2007

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“…This is the site in the resB gene in which insertion of ISAfe1 has been postulated to cause a mutation that is associated with a the loss of iron-oxidizing ability (5). Reversion of this mutant to wild type is associated with the spontaneous loss of ISAfe1 from resB and is accompanied by the removal of the target site duplication, restoring the wild-type DNA sequence (5).…”

Section: Discussionmentioning

confidence: 99%

“…This repetitive element was tentatively identified as an insertion sequence and termed IST1 (renamed ISAfe1 here). Phenotypic switching was shown to be correlated with the high frequency insertion and excision of ISAfe1 into, and out of, the resB gene (5). ResB encodes a cytochrome c-type maturation protein (reviewed in reference 45), and a model was proposed in which insertion of ISAfe1 into resB eliminated the capacity of ResB to satisfactorily mature a c-type cytochrome and that this resulted, in turn, in the loss of the ability to oxidize iron but not sulfur (5).…”

mentioning

confidence: 99%

ISAfe1, an ISL3 Family Insertion Sequence fromAcidithiobacillus ferrooxidansATCC 19859

Holmes¹,

Zhao²,

Levicán³

et al. 2001

J Bacteriol

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Acidithiobacillus ferrooxidans, formerly Thiobacillus ferrooxidans (24), is a gram-negative bacterium that has been shown to be active in the solubilization of copper and in the processing of refractory gold ores in bioleaching operations (reviewed in references 21 and 36). It is also a major contributor to acid mine drainage in copper and coal mines and in certain natural environments. It is a chemolithotroph, deriving energy and electrons from the oxidation of ferrous iron and/or sulfur and various reduced sulfur compounds at pH 2 to 4, using oxygen as the ultimate electron acceptor (22). It fixes CO 2 by the Calvin-Bassham scheme. It can also anaerobically oxidize hydrogen at pH 5.5 (15). Recently, the almost complete genome sequence of A. ferrooxidans was used to detect and inventory the genes involved in amino acid metabolism (40).A mutant of A. ferrooxidans ATCC 19859 has been isolated that is able to switch reversibly, and with high frequency, between a wild-type state, in which it can oxidize both ferrous iron and sulfur compounds, and a mutant state, in which it has lost the capacity to oxidize iron (39). This phenomenon resembles other states of instability associated with the transposition of insertion sequences that have been described in other organisms and led us to investigate whether phenotypic switching might similarly be explained in A. ferrooxidans.Evidence was recently presented (5) that implicated a member of the so-called family 1 repetitive elements (50) in phenotypic switching. This repetitive element was tentatively identified as an insertion sequence and termed IST1 (renamed ISAfe1 here). Phenotypic switching was shown to be correlated with the high frequency insertion and excision of ISAfe1 into, and out of, the resB gene (5). ResB encodes a cytochrome c-type maturation protein (reviewed in reference 45), and a model was proposed in which insertion of ISAfe1 into resB eliminated the capacity of ResB to satisfactorily mature a c-type cytochrome and that this resulted, in turn, in the loss of the ability to oxidize iron but not sulfur (5).In order to describe and explain the phenomenon of phenotypic switching, we carried out a partial molecular characterization of ISAfe1. We further demonstrate that ISAfe1 can promote plasmid integration and resolution in E. coli, opening up the future possibility of exploiting E. coli to test experimentally certain characteristics of this insertion sequence. MATERIALS AND METHODSBacterial strains and media. Strains and plasmids used in this study are listed in Table 1. A. ferrooxidans ATCC 19859 was grown on Mackintosh medium or in modified 9K-ferrous iron medium (50). E. coli was grown in Luria-Bertani (LB) medium (30).Construction of plasmids. Construction of pTf85. A member of family 1 repeated DNA from A. ferrooxidans ATCC 19859 was cloned into pBR322, and the resulting plasmid was designated pTf11 (50). An internal SphI fragment of pTf1 1 was subcloned into pBR322 and termed pTf1 1-sph. pTf1 1-sph was subsequently used as a probe in a Southern blot...

show abstract

IST1 insertional inactivation of the resB gene: implications for phenotypic switching in Thiobacillus ferrooxidans

Cited by 9 publications

References 12 publications

Characterization of the petI and res Operons of Acidithiobacillus ferrooxidans

Characterization of the petI and res Operons of Acidithiobacillus ferrooxidans

Differential expression of two bc 1 complexes in the strict acidophilic chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans suggests a model for their respective roles in iron or sulfur oxidation

ISAfe1, an ISL3 Family Insertion Sequence fromAcidithiobacillus ferrooxidansATCC 19859

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