Identification and characterization of a putative serine protease expressed in vivo by Mycobacterium avium subsp. paratuberculosis

Rm, Cameron; Stevenson, Karen; Nf, Inglis; Klausen, Joan; Jm, Sharp

doi:10.1099/13500872-140-8-1977

Cited by 33 publications

(20 citation statements)

References 27 publications

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“…3). These sequences, along with the serine motif, have been proposed to comprise a His-Asp-Ser active site in HtrA homologs (3).…”

Section: Resultsmentioning

confidence: 99%

“…4. Of these homologs, HtrA (DegP) from E. coli has been purified and shown to have a serine endopeptidase activity (31), in keeping with the presence of the conserved serine protease catalytic domain (the motif GNSGGAL) (3,30,31) which is also present in AlgW. Furthermore, all members of this family of proteins, including AlgW, contain several highly conserved regions, two of which contain invariant His residues and an Asp residue (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Two distinct loci affecting conversion to mucoidy in Pseudomonas aeruginosa in cystic fibrosis encode homologs of the serine protease HtrA

et al. 1996

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Conversion to a mucoid, exopolysaccharide alginate-overproducing phenotype in Pseudomonas aeruginosa is associated with chronic respiratory infections in cystic fibrosis. Mucoidy is caused by muc mutations that derepress the alternative factor AlgU, which in turn activates alginate biosynthetic and ancillary regulatory genes. Here we report the molecular characterization of two newly identified genes, algW and mucD, that affect expression of mucoidy. The algW gene, mapping at 69 min, was isolated on the basis of its ability to suppress mucoidy and reduce transcription of the alginate biosynthetic gene algD. The predicted primary structure of AlgW displayed similarity to HtrA (DegP), a serine protease involved in proteolysis of abnormal proteins and required for resistance to oxidative and heat stress in enteric bacteria. Inactivation of algW on the chromosome of the wild-type nonmucoid strain PAO1 caused increased sensitivity to heat, H 2 O 2 , and paraquat, a redox cycling compound inducing intracellular levels of superoxide. This mutation also permitted significant induction of alginate production in the presence of subinhibitory concentrations of paraquat. Two new genes, mucC and mucD, were identified immediately downstream of the previously characterized portion (algU mucA mucB) of the gene cluster at 67.5 min encoding the alternative factor AlgU and its regulators. Interestingly, the predicted gene product of mucD also showed similarities to HtrA. Inactivation of mucD on the PAO1 chromosome resulted in conversion to the mucoid phenotype. The mutation in mucD also caused increased sensitivity to H 2 O 2 and heat killing. However, in contrast to algW mutants, no increase in susceptibility to paraquat was observed in mucD mutants. These findings indicate that algW and mucD play partially overlapping but distinct roles in P. aeruginosa resistance to reactive oxygen intermediates and heat. In addition, since mutations in mucD and algW cause conversion to mucoidy or lower the threshold for its induction by reactive oxygen intermediates, these factors may repress alginate synthesis either directly by acting on AlgU or its regulators or indirectly by removing physiological signals that may activate this stress response system.Pseudomonas aeruginosa is an opportunistic pathogen causing acute infections in individuals with compromised defense mechanisms, such as burned or neutropenic patients. Another notorious and in many aspects unique infection caused by P. aeruginosa is its characteristic association with the respiratory tract of patients with cystic fibrosis (CF) (8,41,53). This chronic infection differs from the acute disseminated disease by being localized almost exclusively to the lumen of the respiratory tract (1,26,53). Furthermore, the protracted colonization of the respiratory tract is accompanied by a distinct set of phenotypic changes of the bacterium (8, 53). For example, P. aeruginosa strains colonizing CF patients often convert to a mucoid, exopolysaccharide alginate-overproducing phenotype (17), los...

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“…3). These sequences, along with the serine motif, have been proposed to comprise a His-Asp-Ser active site in HtrA homologs (3).…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Two distinct loci affecting conversion to mucoidy in Pseudomonas aeruginosa in cystic fibrosis encode homologs of the serine protease HtrA

et al. 1996

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“…Since PepA has been shown to be expressed by M. avium subsp. paratuberculosis in infected sheep (14), PepA is likely to be expressed by M. tuberculosis growing in macrophages and to play an important role in facilitating survival. Rv1566c is homologous to the p60 invasion-associated protein of Listeria monocytogenes (37).…”

Section: Discussionmentioning

confidence: 99%

Identification of Genes Encoding Exported Mycobacterium tuberculosis Proteins Using a Tn 552′phoA In Vitro Transposition System

et al. 2000

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“…flgal-CA fusion protein was purified by affinity chromatography using a 4 ml column of aminobenzyl 1-thio-fl-galactopyranoside (ABTG) agarose (Sigma) as previously described (Cameron et al, 1994). GST-CA was purified by affinity chromatography using a 4 ml column of glutathione-Sepharose (Pharmacia) as recommended by the manufacturers.…”

Section: Methodsmentioning

confidence: 99%

Epithelial tumour cells in the lungs of sheep with pulmonary adenomatosis are major sites of replication for Jaagsiekte retrovirus

Palmarini

Dewar

Heras

et al. 1995

Journal of General Virology

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Sheep pulmonary adenomatosis (SPA) is a naturally occurring contagious lung tumour of sheep which has been associated aetiologically with a type D-and Brelated retrovirus (Jaagsiekte retrovirus; JSRV). To improve understanding of the aetio-pathogenesis of SPA, the distribution and the sites of JSRV replication in sheep with naturally or experimentally induced SPA or in unaffected controls were identified. New immunological reagents were produced and a blocking enzymelinked immunosorbent assay (B-ELISA) and an immunohistochemical technique for the detection of JSRV major capsid protein at the tissue and cellular levels were developed. JSRV was detected only in the respiratory tract of sheep affected by pulmonary adenomatosis and specifically in the transformed epithelial cells of the alveoli of SPA-affected sheep.

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Identification and characterization of a putative serine protease expressed in vivo by Mycobacterium avium subsp. paratuberculosis

Cited by 33 publications

References 27 publications

Two distinct loci affecting conversion to mucoidy in Pseudomonas aeruginosa in cystic fibrosis encode homologs of the serine protease HtrA

Two distinct loci affecting conversion to mucoidy in Pseudomonas aeruginosa in cystic fibrosis encode homologs of the serine protease HtrA

Identification of Genes Encoding Exported Mycobacterium tuberculosis Proteins Using a Tn 552′phoA In Vitro Transposition System

Epithelial tumour cells in the lungs of sheep with pulmonary adenomatosis are major sites of replication for Jaagsiekte retrovirus

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