Rifamycins: A General View

Riva, Silvano; Silvestri, L. G.

doi:10.1146/annurev.mi.26.100172.001215

Cited by 127 publications

(46 citation statements)

References 120 publications

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“…S5A) indicating that the effect is not secondary to MreB levels. To make sure that the reduction in MreB rotation is not due to transcriptional downregulation, we also treated cells with the RNA polymerase inhibitor rifampicin (21,22), which had no detectable effect on MreB rotation (Fig. S5 B-D).…”

Section: Resultsmentioning

confidence: 99%

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly

Teeffelen

Wang

Furchtgott

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

385

398

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Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yetunidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis.bacterial cytoskeletal dynamics | cell-wall organization | peptidoglycan synthesis | cell growth C ytoskeletal proteins play an important role in bacterial morphogenesis (1). Of the bacterial cytoskeletal proteins, the widely conserved actin homolog MreB is particularly important for bacterial cells to elongate and maintain a rod-like shape. MreB forms polymers that are associated with the cell membrane and distributed along the length of the cell in many rod-shaped bacteria (2). These polymeric MreB structures are essential for the maintenance of rod-like cell shape, as their disruption leads to cell rounding. Although MreB is essential for proper morphogenesis, bacterial cell shape is ultimately determined by the shape of the peptidoglycan cell-wall sacculus, which in turn is controlled by the cell-wall synthesis machinery. The cell wall, which is composed of stiff glycan strands cross-linked by flexible peptide linkers, forms a load-bearing structure that can counteract the intracellular turgor pressure. Cell-wall assembly requires peptidoglycan subunits to be synthesized, polymerized into glycan strands by transglycosylase enzymes, and cross-linked into the existing cell-wall network by transpeptidase enzymes. MreB directly or indirectly associates with a number of proteins that have been implicated in cell-wall assembly, such that MreB is believed to act upstream of the cell-wall assembly machinery to direct the synthesis enzymes to the sites of cell-wall insertion.Previous studies have demonstrated that MreB structures are dynamic in Bacillus subtilis and Caulobacter crescentus (3-7). To date, no motor proteins have been shown to either ...

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Section: Resultsmentioning

confidence: 99%

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly

Teeffelen

Wang

Furchtgott

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

385

398

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“…The polymerases are each composed of a single subunit with a molecular size of about 100 kDa (4). These polymerases are able to promote transcription in the presence of the antibiotic rifampin (56), while the E. coli RNA polymerase is blocked by rifampin (47). The fact that P1 depends on a rifampin-sensitive RNA polymerase throughout lytic development (20a, 41) and the low molecular size of gplO (18.1 kDa) argue against the possibility that P1 encodes its own RNA polymerase.…”

Section: Discussionmentioning

confidence: 99%

Bacteriophage P1 gene 10 encodes a trans-activating factor required for late gene expression

1991

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Amber mutants of bacteriophage P1 were used to identify functions involved in late regulation of the P1 lytic growth cycle. A single function has been genetically identified to be involved in activation of the phage-specific late promoter sequence P. In vivo, P1 gene 10 amber mutants fail to trans activate a lacZ operon fusion under the transcriptional control of promoter Ps. Several P1 segments, mapping around position 95 on the P1 chromosome, were cloned into multicopy plasmid vectors. Some of the cloned DNA segments had a deleterious effect on host cells unless they were propagated in a P1 lysogenic background. By deletion and sequence analysis, the harmful effect could be delimited to a 869-bp P1 fragment, containing a 453-bp open reading frame. This open reading frame was shown to be gene 10 by sequencing the amber mutation amlO.1 and by marker rescue experiments with a number of other gene 10 amber mutants. Gene 10 codes for an 18.1-kDa protein showing an unusually high density of charged amino acid residues. No significant homology to sequences present in the EMBL/GenBank data base was found, and the protein contained none of the currently known DNA-binding motifs. An in vivo trans activation assay system, consisting of gene 10 under the transcriptional control of an inducible promoter and a gene SllacZ fusion transcribed from Ps, was used to show that gene 10 is the only phage-encoded function required for late promoter activation.The temperate bacteriophage P1 propagates on several enterobacterial species, including Escherichia coli (64). The linear DNA molecule carried in a phage particle is about 100 kb in size and has a terminal redundancy of 8 to 12% (32, 65). As a prophage, P1 is a low-copy-number plasmid of about 90 kb (3, 33).The genome of P1 is organized in relatively short transcriptional units and in this respect resembles the virulent bacteriophage T4 (43) rather than the temperate lambdoid phages (57). For example, P1 genes for both immunity control and morphogenesis are widely dispersed over the genome (50,62,63). The presence of at least 14 operator sites for the P1 cI repressor protein (8,15,16,28,29,59) and the tripartite immunity system of the phage (64) indicate the degree of complexity which P1 faces in regulating and expressing its genetic information.While the lysogenic condition of P1 has been studied intensively (for a recent review, see reference 64), relatively little is known about the regulation of the lytic growth cycle. A few functions which are under transcriptional control of the P1 cI repressor have been identified (8,10). Among those is the repL function, which is essential for the lytic replication of the phage genome (9,25,52).Recently, a new class of P1 promoters, controlling the late genes encoded by the tail fiber and the dar operons, has been identified (21,22

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“…Mutations in rpoB can produce resistance to rifampicin, a drug which blocks the initiation of RNA synthesis by binding to the RNA polymerase of normal (rpoB') E. coli strains [3,4]. In strains carrying two copies of' the gene, the sensitive rpoB' allele is dominant over most rpoB mutant alleles coding for rifampicin resistance [3,4].…”

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confidence: 99%

DNA Blockade by Rifampicin‐Inactivated Escherichia coli RNA Polymerase, and Its Amelioration by a Specific Mutation

Hayward

1976

European Journal of Biochemistry

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1. Partially diploid strains of Escherichia coli containing both rifampicin-sensitive and rifampicinresistant RNA polymerase are, in general, sensitive to the drug: of the two copies of the rpoB gene present in such strains, that which codes for sensitive enzyme is dominant.2. RNA polymerase purified from a normal sensitive strain of E. coli, and inactivated by rifampicin, can 'blockade' bacteriophage T7 DNA in vitro, inhibiting its transcription by drugresistant enzyme molecules.3. A mutation, rcs-40, reverses the normal dominance relationship in vivo, without detectably affecting the concentrations of resistant and sensitive RNA polymerase in the diploid cell. I show that rcs-40 is closely linked to the rpoB gene which codes for the rifampicin-sensitive enzyme.4. Rifampicin-sensitive RNA polymerase purified from E. coli rcs-40, although indistinguishable from the normal enzyme by many criteria, is significantly less efficient in the production of drugdependent DNA blockade.The / 3 polypeptide subunit of Escherichia coli K 12 RNA polymerase is determined by the gene rpoB, formerly known as rif [1,2]. Mutations in rpoB can produce resistance to rifampicin, a drug which blocks the initiation of RNA synthesis by binding to the RNA polymerase of normal (rpoB') E. coli strains [3,4]. In strains carrying two copies of' the gene, the sensitive rpoB' allele is dominant over most rpoB mutant alleles coding for rifampicin resistance [3,4]. For example, the strain AJ 38 (rpoB'lKLF10 rpoB70) is sensitive to the drug, although the cells contain nearly equal numbers of rifampicin-sensitive and rifampicin-resistant RNA polymerase molecules (the latter produced by the episomal rpoB70 mutant gene)Earlier reports from this laboratory [5,6] described the strain AJ41, a rifampicin-resistant derivative of AJ38. AJ41 carries a chromosomal mutation(s) which we term rcs-40, and which I here show to be closely linked to the rpoB,C operon. The strain AJ40 (rpoB+ rcs-40/F'luc+), obtained by curing AJ41 of KLFlO rpoB70 through displacement with F'lac ' [5], displays wild-type sensitivity to rifampicin. Nevertheless, when KLF10 rpoB70 is reintroduced into AJ40 and into an otherwise isogenic rcs' strain, the latter yields the usual drug-sensitive heterodiploid (AJ38), whereas AJ40 yields a resistant strain (AJ41) [6]. Evidently, rcs-40 renders rpoB' recessive to rpoB70.PI.-~ -Enzyme. DNA-dependent RNA polymerase or nucleoside triphosphate : RNA nucleotidyl transferase (EC 2.7.7.6).We showed previously [6] that AJ38 and AJ41 contain the same concentrations of drug-sensitive and of resistant RNA polymerase, and that their early responses to rifampicin challenge are identical. This leaves open a number of hypotheses [5] to explain the biochemical basis of the normal rpoB' dominance. Most simply, since rifampicin scarcely affects the binding of sensitive enzyme to DNA [7,8], the drug-inactivated polymerase could cause a blockade of DNA by binding to some or all promoters (initiation sites), thus preventing adequate transcription by drugresistan...

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Rifamycins: A General View

Cited by 127 publications

References 120 publications

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly

The bacterial actin MreB rotates, and rotation depends on cell-wall assembly

Bacteriophage P1 gene 10 encodes a trans-activating factor required for late gene expression

DNA Blockade by Rifampicin‐Inactivated Escherichia coli RNA Polymerase, and Its Amelioration by a Specific Mutation

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