Identification of
            <i>Bdellovibrio bacteriovorus</i>
            HD100 Bd0714 as a Nudix dGTPase

Steyert, Susan R.; Messing, Simon; Amzel, L. Mario; Gabelli, Sandra B.; Piñeiro, Silvia A.

doi:10.1128/jb.01009-08

Cited by 12 publications

(16 citation statements)

References 28 publications

(12 reference statements)

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“…Pineiro and co-workers [43] mutagenised a Bdellovibrio nudix hydrolase gene Bd0714 but found that it had no effect upon the predatory growth of the bacteria, our studies support this showing that in comparison to attack-phase growth Bd0714 was up-regulated in HI growth, but showed no change in expression at 30 minutes post-predation.…”

Section: Resultssupporting

confidence: 75%

The First Bite— Profiling the Predatosome in the Bacterial Pathogen Bdellovibrio

et al. 2010

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Bdellovibrio bacteriovorus is a Gram-negative bacterium that is a pathogen of other Gram-negative bacteria, including many bacteria which are pathogens of humans, animals and plants. As such Bdellovibrio has potential as a biocontrol agent, or living antibiotic. B. bacteriovorus HD100 has a large genome and it is not yet known which of it encodes the molecular machinery and genetic control of predatory processes. We have tried to fill this knowledge-gap using mixtures of predator and prey mRNAs to monitor changes in Bdellovibrio gene expression at a timepoint of early-stage prey infection and prey killing in comparison to control cultures of predator and prey alone and also in comparison to Bdellovibrio growing axenically (in a prey-or host independent “HI” manner) on artificial media containing peptone and tryptone. From this we have highlighted genes of the early predatosome with predicted roles in prey killing and digestion and have gained insights into possible regulatory mechanisms as Bdellovibrio enter and establish within the prey bdelloplast. Approximately seven percent of all Bdellovibrio genes were significantly up-regulated at 30 minutes of infection- but not in HI growth- implicating the role of these genes in prey digestion. Five percent were down-regulated significantly, implicating their role in free-swimming, attack-phase physiology. This study gives the first post- genomic insight into the predatory process and reveals some of the important genes that Bdellovibrio expresses inside the prey bacterium during the initial attack.

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Section: Resultssupporting

confidence: 75%

The First Bite— Profiling the Predatosome in the Bacterial Pathogen Bdellovibrio

et al. 2010

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“…RT-PCR analyses carried out on RNA samples taken at intervals from synchronous B. bacteriovorus infections were used to monitor the expression of mreB1/mreB2 and mreCD. The RT-PCR had the number of amplification steps limited, so as not proceed to saturation and can therefore be used as a semiquantitative measure of gene expression across a B. bacteriovorus infection cycle, as confirmed previously in comparison to quantitative RT-PCR (10,34). Multiple sets of reactions on a minimum of two independently prepared RNA sample sets are summarized in Fig.…”

Section: Resultsmentioning

confidence: 95%

Manipulating Each MreB ofBdellovibrio bacteriovorusGives Diverse Morphological and Predatory Phenotypes

et al. 2010

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We studied the two mreB genes, encoding actinlike cytoskeletal elements, in the predatory bacterium Bdellovibrio bacteriovorus. This bacterium enters and replicates within other Gram-negative bacteria by attackphase Bdellovibrio squeezing through prey outer membrane, residing and growing filamentously in the prey periplasm forming an infective "bdelloplast," and septating after 4 h, once the prey contents are consumed. This lifestyle brings challenges to the Bdellovibrio cytoskeleton. Both mreB genes were essential for viable predatory growth, but C-terminal green fluorescent protein tagging each separately with monomeric tealfluorescent protein (mTFP) gave two strains with phenotypic changes at different stages in predatory growth and development. MreB1-mTFP cells arrested growth early in bdelloplast formation, despite successful degradation of prey nucleoid. A large population of stalled bdelloplasts formed in predatory cultures and predation proceeded very slowly. A small proportion of bdelloplasts lysed after several days, liberating MreB1-mTFP attack-phase cells of wild-type morphology; this process was aided by subinhibitory concentrations of an MreB-specific inhibitor, A22. MreB2-mTFP, in contrast, was predatory at an almost wild-type rate but yielded attack-phase cells with diverse morphologies, including spherical, elongated, and branched, the first time such phenotypes have been described. Wild-type predatory rates were seen for all but spherical morphotypes, and septation of elongated morphotypes was achieved by the addition of A22.The predatory bacterium Bdellovibrio bacteriovorus shows novel filamentous growth within the periplasm of the Gramnegative prey bacterium on which it feeds. This study focuses on the cytoskeletal protein MreB and the role that two homologues of it play in B. bacteriovorus predatory or host-dependent (HD) growth. The HD B. bacteriovorus life cycle can be split into two phases: an attack phase and a growth phase (Fig.

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“…In summary, 8-oxo-dGMP is surrounded by 12 types of hydrogen bonds. The hydrogen-bonding interactions with the pyrimidine moiety and the ␣-phosphate group in MutT-8-oxo-dGMP are similar to those with the corresponding pyrimidine moieties and ␣-phosphate groups in the structures of BdRppH-GTP-Mg 2ϩ and BdRppH-dGTP (BdRppH- (7,44). This may derive from these structural differences, in addition to the unfavorable syn conformation of (d)GTPs in BdRppH-(d)GTPs.…”

Section: Resultsmentioning

confidence: 92%

Structural and Dynamic Features of the MutT Protein in the Recognition of Nucleotides with the Mutagenic 8-Oxoguanine Base

Nakamura

Meshitsuka

Kitagawa

et al. 2010

Journal of Biological Chemistry

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Escherichia coli MutT hydrolyzes 8-oxo-dGTP to 8-oxodGMP, an event that can prevent the misincorporation of 8-oxoguanine opposite adenine in DNA. Of the several enzymes that recognize 8-oxoguanine, MutT exhibits high substrate specificity for 8-oxoguanine nucleotides; however, the structural basis for this specificity is unknown. The crystal structures of MutT in the apo and holo forms and in the binary and ternary forms complexed with the product 8-oxodGMP and 8-oxo-dGMP plus Mn 2؉ , respectively, were determined. MutT strictly recognizes the overall conformation of 8-oxo-dGMP through a number of hydrogen bonds. This recognition mode revealed that 8-oxoguanine nucleotides are discriminated from guanine nucleotides by not only the hydrogen bond between the N7-H and O␦ (N119) atoms but also by the syn glycosidic conformation that 8-oxoguanine nucleotides prefer. Nevertheless, these discrimination factors cannot by themselves explain the roughly 34,000-fold difference between the affinity of MutT for 8-oxo-dGMP and dGMP. When the binary complex of MutT with 8-oxo-dGMP is compared with the ligand-free form, ordering and considerable movement of the flexible loops surrounding 8-oxodGMP in the binary complex are observed. These results indicate that MutT specifically recognizes 8-oxoguanine nucleotides by the ligand-induced conformational change.Although spontaneous mutations are indispensable to the evolutionary process of living organisms, they can also be lethal to the organism. Among the various modified bases in DNA, RNA, and nucleotides, 8-oxoguanine (8-oxoG), 2 a damaged form of guanine (G) generated by reactive oxygen species, is known to have highly mutagenic potency because of its mispairing with adenine. Therefore, organisms have an error avoidance pathway for preventing mutations caused by 8-oxoG. The Escherichia coli MutT protein (129 amino acids, M r ϭ 14,900) hydrolyzes 8-oxo-dGTP and 8-oxo-GTP to their corresponding nucleoside monophosphates and inorganic pyrophosphate in the presence of Mg 2ϩ (1, 2). Because 8-oxodGTP and 8-oxo-GTP can be misincorporated opposite adenine by DNA and RNA polymerases, the hydrolysis of the damaged nucleotides by MutT can avoid replicational and transcriptional errors. In DNA, 8-oxoG paired with cytosine is excised by MutM, an 8-oxoG DNA glycosylase, whereas MutY, an adenine DNA glycosylase, removes adenine paired with 8-oxoG (3-6).The substrate specificities of enzymes that recognize 8-oxoG are quite varied. MutT exhibits high substrate specificity for 8-oxoG nucleotides; that is, the K m for 8-oxo-dGTP is 14,000-fold lower than that for dGTP (7). In contrast, human MutT homologue 1 (hMTH1) hydrolyzes not only 8-oxo-dGTP but also several oxidized purine nucleotides such as 2-oxo-dATP, 2-oxo-ATP, 8-oxo-dATP, and 8-oxo-ATP. In terms of the hydrolysis of 8-oxo-dGTP, the K m of hMTH1 for 8-oxo-dGTP is only 17-fold lower than that for dGTP (8, 9). The solution structure of hMTH1 as determined by NMR has revealed its overall architecture and possible substrate-binding region ...

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Identification of Bdellovibrio bacteriovorus HD100 Bd0714 as a Nudix dGTPase

Cited by 12 publications

References 28 publications

The First Bite— Profiling the Predatosome in the Bacterial Pathogen Bdellovibrio

The First Bite— Profiling the Predatosome in the Bacterial Pathogen Bdellovibrio

Manipulating Each MreB ofBdellovibrio bacteriovorusGives Diverse Morphological and Predatory Phenotypes

Structural and Dynamic Features of the MutT Protein in the Recognition of Nucleotides with the Mutagenic 8-Oxoguanine Base

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