Genome structure in the vole bacillus, Mycobacterium microti, a member of the Mycobacterium tuberculosis complex with a low virulence for humans

Frota, Cristiane Cunha; Hunt, Debbie M.; Buxton, Roger S.; Rickman, Lisa; Hinds, Jason; Kremer, Kristin; Soolingen, Dick van; Colston, M. Joseph

doi:10.1099/mic.0.26660-0

Cited by 47 publications

(35 citation statements)

References 38 publications

(60 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We noticed that in M. bovis, the region upstream of espA and the adjacent gene [Rv3617 (ephA) in M. tuberculosis] was much shorter than in M. tuberculosis, (465 bp rather than 1,357 bp); in fact, ephA is deleted from M. bovis. This deletion has been annotated as RD8 in M. bovis BCG by Gordon et al (22) and as RD9 by Behr et al (6), and this deletion has also been previously noted in Mycobacterium africanum cluster II (10) and in Mycobacterium microti (10,17). This implies that sequences upstream of Ϫ465 bp relative to the translational start of espA, which includes the EAR, are not required for virulence since M. bovis is, of course, virulent.…”

Section: Figmentioning

confidence: 92%

Long-Range Transcriptional Control of an Operon Necessary for Virulence-Critical ESX-1 Secretion in Mycobacterium tuberculosis

Hunt¹,

Sweeney²,

Mori³

et al. 2012

J Bacteriol

Self Cite

View full text Add to dashboard Cite

bThe ESX-1 secretion system of Mycobacterium tuberculosis has to be precisely regulated since the secreted proteins, although required for a successful virulent infection, are highly antigenic and their continued secretion would alert the immune system to the infection. The transcription of a five-gene operon containing espACD-Rv3613c-Rv3612c, which is required for ESX-1 secretion and is essential for virulence, was shown to be positively regulated by the EspR transcription factor. Thus, transcription from the start site, found to be located 67 bp upstream of espA, was dependent upon EspR enhancer-like sequences far upstream (between 884 and 1,004 bp), which we term the espA activating region (EAR). The EAR contains one of the known binding sites for EspR, providing the first in vivo evidence that transcriptional activation at the espA promoter occurs by EspR binding to the EAR and looping out DNA between this site and the promoter. Regulation of transcription of this operon thus takes place over long regions of the chromosome. This regulation may differ in some members of the M. tuberculosis complex, including Mycobacterium bovis, since deletions of the intergenic region have removed the upstream sequence containing the EAR, resulting in lowered espA expression. Consequent differences in expression of ESX-1 in these bacteria may contribute to their various pathologies and host ranges. The virulence-critical nature of this operon means that transcription factors controlling its expression are possible drug targets.A critical factor in the interaction of Mycobacterium tuberculosis, the causative agent of tuberculosis, with its host cell is the ESX-1 secretion system (for reviews, see references 1, 7, and 50). This system, also termed type VII secretion, transports proteins into host cells and is necessary for the virulence of M. tuberculosis (26,37,53). ESX-1 has been implicated in immune modulation, with the major secreted substrates being the potent antigens ESAT-6 and CFP-10 (also designated EsxA and EsxB) (9, 23, 32, 52). The genes encoding these proteins, together with core components of the system, are located within the region of difference 1 (RD1) locus, which is absent in the attenuated vaccine strain Mycobacterium bovis BCG (9, 18, 31). Unlike type II and IV secretion systems in other bacteria, which are produced in a regulated manner only during infection, the expression of the ESX-1 system itself does not appear to be induced in vivo (47, 54). However, in addition to the genes located in RD1, a separate locus (Rv3616c-Rv3615c-Rv3614c, also designated espA, espC, and espD) is required for ESX-1 function (15, 30). Like the esxA and esxB genes coding for ESAT-6 and CFP-10, the espA and espC genes in this second region are among the most highly expressed in vitro (49) and are necessary for ESX-1 secretion activity, with the EspA and EspC proteins themselves being ESX-1 substrates. Thus, a notable feature of the ESX-1 secretion system is the mutually dependent nature of protein export; i.e., the secretion ...

show abstract

Section: Figmentioning

confidence: 92%

Long-Range Transcriptional Control of an Operon Necessary for Virulence-Critical ESX-1 Secretion in Mycobacterium tuberculosis

Hunt¹,

Sweeney²,

Mori³

et al. 2012

J Bacteriol

Self Cite

View full text Add to dashboard Cite

show abstract

“…M. bovis BCG has a major deletion, designated RD1, in this region (Fig. 3), and different strains of Mycobacterium microti, a member of the M. tuberculosis complex that causes tuberculosis in voles, also have a variety of major deletions in this area (15). These deletions include esxA and esxB and contribute to the attenuation of these strains in mice as revealed by RD1 complementation studies (29).…”

Section: Discussionmentioning

confidence: 99%

Generation of Attenuated Mycobacterium bovis Strains by Signature-Tagged Mutagenesis for Discovery of Novel Vaccine Candidates

et al. 2005

View full text Add to dashboard Cite

Mycobacterium bovis, a member of the Mycobacterium tuberculosis complex, has a particularly wide host range and causes tuberculosis in most mammals, including humans. A signature tag mutagenesis approach, which employed illegitimate recombination and infection of guinea pigs, was applied to M. bovis to discover genes important for virulence and to find potential vaccine candidates. Fifteen attenuated mutants were identified, four of which produced no lesions when inoculated separately into guinea pigs. One of these four mutants had nine deleted genes including mmpL4 and sigK and, in guinea pigs with aerosol challenge, provided protection against tuberculosis at least equal to that of M. bovis BCG. Seven mutants had mutations near the esxA (esat-6) locus, and immunoblot analysis of these confirmed the essential role of other genes at this locus in the secretion of EsxA (ESAT-6) and EsxB (CFP10). Mutations in the eight other attenuated mutants were widely spread through the chromosome and included pks1, which is naturally inactivated in clinical strains of M. tuberculosis. Many genes identified were different from those found by signature tag mutagenesis of M. tuberculosis by use of a mouse infection model and illustrate how the use of different approaches enables identification of a wider range of attenuating mutants.Tuberculosis exacts enormous human suffering and death on a global basis and is also a widespread cause of animal morbidity and mortality. The primary human pathogen is Mycobacterium tuberculosis, although in many regions a significant amount of human disease results from infection with the very closely related organisms Mycobacterium africanum and the major animal pathogen Mycobacterium bovis. Together with a few less important species, these organisms are collectively referred to as the M. tuberculosis complex. The high degree of similarity in the pathogenesis of disease caused by these pathogens and the recent findings from genomic studies that the vast majority of genes within these species are identical or nearly so (16,22) clearly indicate that the majority of their virulence genes are shared in common. There is particular interest in discovering the identity of these genes, so that new strategies including improved vaccines and antibacterials can be developed for combating tuberculosis.Over the last 15 years, there has been continual development of molecular genetic techniques that can be applied to the M. tuberculosis complex (2). This enabled the discovery of individual tuberculosis virulence genes from 1995 onwards (7, 38) and led to the application over the last 5 years of a number of global techniques for identifying large numbers of genes that are essential for virulence or whose expression is altered during different stages of infection and disease. Among these global techniques, signature tag mutagenesis (18) is widely recognized as a powerful tool for investigating pathogenic organisms because of its ability to directly identify mutants that have reduced virulence (24). This identific...

show abstract

“…An AscI site is lost when the Rv1747 gene was deleted so that an ϳ7-kb fragment that hybridized with the pknE probe and an ϳ10-kb fragment that hybridized with the fad1 probe were replaced by an ϳ15-kb fragment (data not shown). Genomic DNA was isolated and used to probe M. tuberculosis DNA microarrays as described previously (14).…”

Section: Methodsmentioning

confidence: 99%

An ABC Transporter Containing a Forkhead-Associated Domain Interacts with a Serine-Threonine Protein Kinase and Is Required for Growth of Mycobacterium tuberculosis in Mice

Curry¹,

Whalan²,

Hunt³

et al. 2005

Infect Immun

Self Cite

View full text Add to dashboard Cite

Forkhead-associated (FHA) domains are modular phosphopeptide recognition motifs with a striking preference for phosphothreonine-containing epitopes. FHA domains have been best characterized in eukaryotic signaling pathways but have been identified in six proteins in Mycobacterium tuberculosis, the causative organism of tuberculosis. One of these, coded by gene Rv1747, is an ABC transporter and the only one to contain two such modules. A deletion mutant of Rv1747 is attenuated in a mouse intravenous injection model of tuberculosis where the bacterial load of the mutant is 10-fold lower than that of the wild type in both lungs and spleen. In addition, growth of the mutant in mouse bone marrow-derived macrophages and dendritic cells is significantly impaired. In contrast, growth of this mutant in vitro was indistinguishable from that of the wild type. The mutant phenotype was lost when the mutation was complemented by the wild-type allele, confirming that it was due to mutation of Rv1747. Using yeast two-hybrid analysis, we have shown that the Rv1747 protein interacts with the serine-threonine protein kinase PknF. This interaction appears to be phospho-dependent since it is abrogated in a kinase-dead mutant and by mutations in the presumed activation loop of PknF and in the first FHA domain of Rv1747. These results demonstrate that the protein coded by Rv1747 is required for normal virulent infection by M. tuberculosis in mice and, since it interacts with a serine-threonine protein kinase in a kinase-dependent manner, indicate that it forms part of an important phospho-dependent signaling pathway.

show abstract

Genome structure in the vole bacillus, Mycobacterium microti, a member of the Mycobacterium tuberculosis complex with a low virulence for humans

Cited by 47 publications

References 38 publications

Long-Range Transcriptional Control of an Operon Necessary for Virulence-Critical ESX-1 Secretion in Mycobacterium tuberculosis

Long-Range Transcriptional Control of an Operon Necessary for Virulence-Critical ESX-1 Secretion in Mycobacterium tuberculosis

Generation of Attenuated Mycobacterium bovis Strains by Signature-Tagged Mutagenesis for Discovery of Novel Vaccine Candidates

An ABC Transporter Containing a Forkhead-Associated Domain Interacts with a Serine-Threonine Protein Kinase and Is Required for Growth of Mycobacterium tuberculosis in Mice

Contact Info

Product

Resources

About