Mark S Paget

• PhD
• Lecturer at University of Sussex

The major oxidative stress response in Streptomyces is controlled by the sigma factor SigR and its cognate antisigma factor RsrA, and SigR activity is tightly controlled through multiple mechanisms at both the transcriptional and posttranslational levels. Here we show that sigR has a highly unusual GTC start codon and that this leads to another lev...

Mismatch repair (MMR) is a near ubiquitous pathway, essential for the maintenance of genome stability. Members of the MutS and MutL protein families perform key steps in mismatch correction. Despite the major importance of this repair pathway, MutS–MutL are absent in almost all Actinobacteria and many Archaea. However, these organisms exhibit rates...

Supplementary Figures, Supplementary Tables, Supplementary Methods, and Supplementary References

Taxonomic tree for phylogenetic profiling in newick format. Raw NCBI profiling tree from archaeal and bacterial species extracted from NCBI in newick format, corresponding to Figure 5.

Phylogenetic tree of full NucS in newick format. Raw Maximum Likelihood and bootstrap phylogenetic tree corresponding to Supplementary Figure 5 (full NucS) in newick format.

Phylogenetic tree of C-terminal NucS in newick format. Raw Maximum Likelihood and bootstrap phylogenetic tree corresponding to Supplementary Figure 6 (NucS-CT region) in newick format.

Taxonomic distribution of NucS and MutS-MutL in reference proteomes (Big excel data file).

Detailed information for phylogenetic trees of NucS regions. Sequence details of NucS-CT and NucS-NT labels on Supplementary Figures 6-7 trees (Excel file).

Phylogenetic tree of N-terminal NucS in newick format. Raw Maximum Likelihood and bootstrap phylogenetic tree corresponding to Supplementary figure 7 (NucS-NT region) in newick format.

Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP) that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (...

Significance Initiation of transcription in bacteria relies on a multisubunit RNA polymerase in concert with a dissociable σ-subunit that confers promoter recognition and opening to reveal the DNA template strand. RbpA, a transcription activator unique to Actinobacteria and essential in Mycobacterium tuberculosis , associates tightly with σ and is...

SynopsisIn bacteria, sigma factors are dissociable protein subunits of RNA polymerase that play a key role in promoter selection and transcription initiation. Together with an essential principal sigma factor that is required for the expression of most housekeeping genes, bacteria often deploy alternative sigma factors in response to specific signa...

RbpA is a small non–DNA-binding transcription factor that associates with RNA polymerase holoenzyme and stimulates transcription in actinobacteria, including Streptomyces coelicolor and Mycobacterium tuberculosis. RbpA seems to show specificity for the vegetative form of RNA polymerase as opposed to alternative forms of the enzyme. Here, we explain...

Nicotinamide adenine dinucleotides have emerged as key signals of the cellular redox state. Yet the structural basis for allosteric gene regulation by the ratio of reduced NADH to oxidized NAD(+) is poorly understood. A key sensor among Gram-positive bacteria, Rex represses alternative respiratory gene expression until a limited oxygen supply eleva...

Diamide is an artificial disulphide-generating electrophile that mimics an oxidative shift in the cellular thiol-disulphide redox state (disulphide stress). The Gram-positive bacterium Streptomyces coelicolor senses and responds to disulphide stress through the sigma(R)-RsrA system, which comprises an extracytoplasmic function (ECF) sigma factor an...

Streptomyces coelicolor mutants lacking the zinc-responsive Zur repressor are conditionally defective in sporulation, presumably due to the overexpression of one or more Zur target genes. Gene disruption analyses revealed that deregulation of previously known Zur targets was not responsible for the sporulation phenotype. We used microarrays to iden...

Streptomyces coelicolor contains paralogous versions of seven ribosomal proteins (S14, S18, L28, L31, L32, L33, and L36), which differ in their potential to bind structural zinc. The paralogues are termed C+ or C− on the basis of the presence or absence of putative cysteine ligands. Here, mutational studies suggest that the C− version of L31 can fu...

ZAS proteins are widespread bacterial zinc-containing anti-sigma factors that regulate the activity of sigma factors in response to diverse cues. One of the best characterized ZAS proteins is RsrA from Streptomyces coelicolor, which responds to disulfide stress. Zn-RsrA binds and represses the transcriptional activity of sigmaR in the reducing envi...

RbpA is an RNA polymerase-binding protein that occurs in the actinomycete family of bacteria and is regulated by the disulphide stress-response sigma factor, sigma(R), in Streptomyces coelicolor. Here we demonstrate that rbpA null mutants exhibit a slow-growth phenotype and are particularly sensitive to the transcription inhibitor rifampicin. Strik...

The redox-sensing repressor Rex regulates transcription of respiratory genes in response to the intra cellular NADH/NAD(+) redox poise. As a step toward elucidating the molecular mechanism of NADH/NAD(+) sensing, the X-ray structure of Thermus aquaticus Rex (T-Rex) bound to effector NADH has been determined at 2.9 A resolution. The fold of the C-te...

Redox reactions pervade living cells. They are central to both anabolic and catabolic metabolism. The ability to maintain redox balance is therefore vital to all organisms. Various regulatory sensors continually monitor the redox state of the internal and external environments and control the processes that work to maintain redox homeostasis. In re...

Vancomycin is the front-line therapy for treating problematic infections caused by methicillin-resistant Staphylococcus aureus (MRSA), and the spread of vancomycin resistance is an acute problem. Vancomycin blocks cross-linking between peptidoglycan intermediates by binding to the D-Ala-D-Ala termini of bacterial cell wall precursors, which are the...

The regulation of disulphide stress in actinomycetes such as Streptomyces coelicolor is known to involve the zinc-containing anti-sigma factor RsrA that binds and inactivates the redox-regulated sigma factor sigmaR. However, it is not known how RsrA senses disulphide stress nor what role the metal ion plays. Using in vitro assays, we show that whil...

We describe the identification of Rex, a novel redox-sensing repressor that appears to be widespread among Gram-positive bacteria. In Streptomyces coelicolor Rex binds to operator (ROP) sites located upstream of several respiratory genes, including the cydABCD and rex-hemACD operons. The DNA-binding activity of Rex appears to be controlled by the r...

Members of the sigma70 family of sigma factors are components of the RNA polymerase holoenzyme that direct bacterial or plastid core RNA polymerase to specific promoter elements that are situated 10 and 35 base-pairs upstream of transcription-initiation points. Members of the sigma70 family also function as contact points for some activator protein...

Thiol-based regulatory switches play central roles in cellular responses to oxidative stress, nitrosative stress, and changes in the overall thiol-disulfide redox balance. Protein sulfhydryls offer a great deal of flexibility in the different types of modification they can undergo and the range of chemical signals they can perceive. For example, re...

The extracytoplasmic function (ECF) sigma factor sigma(R) is a global regulator of redox homeostasis in the antibiotic-producing bacterium Streptomyces coelicolor, with a similar role in other actinomycetes such as Mycobacterium tuberculosis. Normally maintained in an inactive state by its bound anti-sigma factor RsrA, sigma(R) dissociates in respo...

We have investigated a signal transduction system proposed to allow Streptomyces coelicolor to sense and respond to changes in the integrity of its cell envelope. The system consists of four proteins, encoded in an operon: sigmaE, an RNA polymerase factor; CseA (formerly ORF202), a protein of unknown function; CseB, a response regulator; and CseC,...

In the Gram-positive, antibiotic-producing bacterium Streptomyces coelicolor A3(2), the thiol-disulphide status of the hyphae is controlled by a novel regulatory system consisting of a sigma factor, sigmaR, and its cognate anti-sigma factor, RsrA. Oxidative stress induces intramolecular disulphide bond formation in RsrA, which causes it to lose aff...

In the Gram-positive bacterium, Streptomyces coelicolor A3(2), expression of the thioredoxin system is modulated by a sigma factor called sigmaR in response to changes in the cytoplasmic thiol-disulphide status, and the activity of sigmaR is controlled post-translationally by an anti-sigma factor, RsrA. In vitro, the anti-sigma factor activity of R...

In the Gram-positive bacterium, Streptomyces coelicolor A3(2), expression of the thioredoxin system is modulated by a sigma factor called σR in response to changes in the cytoplasmic thiol–disulphide status, and the activity of σR is controlled post-translationally by an anti-sigma factor, RsrA. In vitro, the anti-sigma factor activity of RsrA, whi...

On Nov 26, 1999 this sequence version replaced gi:3688547.

SigR (sigma(R)) is a sigma factor responsible for inducing the thioredoxin system in response to oxidative stress in the antibiotic-producing, Gram-positive bacterium Streptomyces coelicolor A3(2). Here we identify a redox-sensitive, sigma(R)-specific anti-sigma factor, RsrA, which binds sigma(R) and inhibits sigma(R)-directed transcription in vitr...

The extracytoplasmic function (ECF) sigma factor, sigmaE, is required for normal cell wall integrity in Streptomyces coelicolor. We have investigated the regulation of sigmaE through a transcriptional and mutational analysis of sigE and the surrounding genes. Nucleotide sequencing identified three genes located downstream of sigE; orf202, cseB and...

The sigE gene of Streptomyces coelicolor A3(2) encodes an RNA polymerase sigma factor belonging to the extracytoplasmic function (ECF) subfamily. Constructed sigE deletion and disruption mutants were more sensitive than the parent to muramidases such as hen egg white lysozyme and to the CwlA amidase from Bacillus subtilis. This correlated with an a...

We have identified an RNA polymerase sigma factor, sigmaR, that is part of a system that senses and responds to thiol oxidation in the Gram-positive, antibiotic-producing bacterium Streptomyces coelicolor A3(2). Deletion of the gene (sigR) encoding sigmaR caused sensitivity to the thiol-specific oxidant diamide and to the redox cycling compounds me...

The phsA gene encodes phenoxazinone synthase (PHS), which catalyses the penultimate step in the pathway for actinomycin biosynthesis in Streptomyces antibioticus. The phsA promoter strikingly resembles a putative Streptomyces sigma E cognate promoter, and purified E sigma E holoenzyme transcribed the phsA promoter in vitro. However, the phsA promot...

We have constructed multicopy and integrative streptomycete promoter probe vectors that employ the promoterless tyrosinase (melC) operon of Streptomyces glaucescens as the chromogenic transcriptional reporter. Each vector contains the reporter cassette, RC3, which comprises part of the melC operon flanked by transcription terminators; RC3 may be ea...