Extracellular proteolytic enzyme activity ofHistoplasma capsulatum var.duboisii

Muotoe-Okafor, Florence A.; Gugnani, H. C.; Obidoa, Onyechi

doi:10.1007/bf02373018

Cited by 13 publications

(8 citation statements)

References 19 publications

(10 reference statements)

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“…duboisii and H. capsulatum var. capsulatum (Okeke and Muller, 1991a, Okeke and Muller, 1991b, Muotoe-Okafor et al, 1996. The discrepancies observed between these studies and our work are probably due to differences in methodology, especially in the media tested.…”

Section: Discussioncontrasting

confidence: 75%

“…Dimorphic fungi consist of six phylogenetically related ascomycetes: Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, Paracoccidioides brasiliensis, Penicillium marneffei, and Sporothrix schenckii, but only few studies have shown proteolytic activity in vitro (Tsuboi et al, 1986, Sanada, 1987, Tsuboi et al, 1987, Cole et al, 1992, Carmona et al, 1995, Puccia et al, 1998, de Assis et al, 1999, Moon et al, 2006. There are also relatively few reports describing this type of activity in H. capsulatum (Okeke and Muller, 1991a, Okeke and Muller, 1991b, Muotoe-Okafor et al, 1996.…”

Section: Discussionmentioning

confidence: 99%

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Production of extracellular proteolytic activity by Histoplasma capsulatum grown in Histoplasma-macrophage medium is limited to restriction fragment length polymorphism class 1 isolates

Żarnowski

Connolly²,

Wheat³

et al. 2007

Diagnostic Microbiology and Infectious Disease

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Extracellular proteolytic activity was studied for 28 strains of Histoplasma capsulatum var. capsulatum and 2 strains of H. capsulatum var. duboisii. Secreted protease activity assessed by skim milk agarose clearance was limited solely to H. capsulatum var. capsulatum restriction fragment length polymorphism (RFLP) class 1 strains. There was a difference in proteolytic activity levels among class 1 strains. Extracellular proteolytic activity was further determined during growth of those strains in liquid medium using azodye-impregnated protein substrates. In general, the highest activities were measured when azocollagen was used, whereas azocasein and azoalbumin were cleaved less efficiently. The activity was inhibited by phenylmethylsulfonyl fluoride, 4-(2-aminoethyl) benzenesulfonyl fluoride, antipain, and chymostatin, indicating, thereby, the presence of chymotrypsin-like serine proteases. Chromatographic analyses as well as variable substrate use at different culture times revealed production of at least 2 different enzyme pools of the same serine-like protease family. Our results demonstrate a distinctive ability of RFLP class 1 isolates to produce and secrete serine proteinase-type activity. This peculiarity may be relevant to the biology and pathogenesis of this particular clade of H. capsulatum isolates. Overall, the feature of extracellular proteolytic activity production enables a convenient and unequivocal identification of RFLP class 1 isolates and, thereby, can be used in H. capsulatum strain differentiation and typing.

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Section: Discussioncontrasting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Production of extracellular proteolytic activity by Histoplasma capsulatum grown in Histoplasma-macrophage medium is limited to restriction fragment length polymorphism class 1 isolates

Żarnowski

Connolly²,

Wheat³

et al. 2007

Diagnostic Microbiology and Infectious Disease

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“…Some of the fungal virulence factors identified to date include proteases, such as the secreted aspartyl proteases from Candida albicans (20,22). Extracellular proteolytic activity has been described previously in H. capsulatum and shown to hydrolyze casein, bovine serum albumin, and collagen (21,23,24,30). However, H. capsulatum protease genes have not been identified.…”

mentioning

confidence: 99%

Secreted Dipeptidyl Peptidase IV Activity in the Dimorphic Fungal PathogenHistoplasma capsulatum

Cooper

Woods

2009

Infect Immun

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Dipeptidyl peptidase type IV (DppIV) enzymes are broadly distributed phylogenetically and display diverse functions, including intercellular signaling, immunomodulation, protein maturation and processing, metabolism, and nutrient acquisition. We identified a secreted proteolytic activity in Histoplasma capsulatum effective toward DppIV-specific substrates. In order to determine the gene(s) that encodes this activity, we identified two putative DPPIV homologs (HcDPPIVA and HcDPPIVB) in H. capsulatum based on a homology search with Aspergillus fumigatus DppIV. Comparative sequence analysis revealed that HcDppIVA is similar to secreted DppIV enzymes, while HcDppIVB clusters with intracellular DapB-like enzymes. Unexpectedly, silencing of HcDPPIVA by RNA interference (RNAi) had no effect on secreted DppIV activity and an HcDPPIVA-null deletion mutant also showed no abrogation of secreted DppIV activity. In contrast, RNAi silencing of HcDPPIVB significantly reduced the level of secreted DppIV activity. RNAi silencing of HcDPPIVB in the HcDPPIVA-null mutant had no additional effect on secreted DppIV activity, indicating that HcDPPIVA does not contribute to secreted activity. RNAi silencing of HcDPPIVB did not affect the ability to kill a murine macrophage-like cell line, RAW 264.7, indicating that this gene is not required for infection of macrophages.

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“…The aspartic protease activity was more pronounced in yeasts than in mycelia [149]. The optimum temperature and pH for maximum proteolytic activity were 35°C and 6.8, respectively.…”

Section: Aspartic Proteasesmentioning

confidence: 89%

Aspartic Proteases of Human Pathogenic Fungi are Prospective Targets for the Generation of Novel and Effective Antifungal Inhibitors

Santos

2011

CEI

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Fungi can cause life-threatening diseases, particularly in patients with weakened immunological systems. Although treatment options are available for these individuals, dose-limiting toxicity and the appearance of drug-resistant microorganisms are growing problems. Detailed structural and functional characterization of fungal proteases has led to novel insights into the workings of these fascinating catalytic machines. Identification and characterization of proteasemediated processes in human pathogenic fungi is progressing at a rapid rate. In these microorganisms, aspartic-type proteases carry out "housekeeping" tasks common to many eukaryotes as well as functions highly specific to the fungal life cycles. Consequently, the possibility of developing selective inhibitors of key aspartic proteases of pathogenic fungi into novel chemotherapeutic strategies is being vigorously explored. The present review describes the knowledge in the area of aspartic proteases produced by human fungal pathogens. As well, the effects of aspartic proteolytic inhibitors on multiple vital processes of fungal cells, with special emphasis on their roles to arrest fungal development and virulence, will be presented and discussed.

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Extracellular proteolytic enzyme activity ofHistoplasma capsulatum var.duboisii

Cited by 13 publications

References 19 publications

Production of extracellular proteolytic activity by Histoplasma capsulatum grown in Histoplasma-macrophage medium is limited to restriction fragment length polymorphism class 1 isolates

Production of extracellular proteolytic activity by Histoplasma capsulatum grown in Histoplasma-macrophage medium is limited to restriction fragment length polymorphism class 1 isolates

Secreted Dipeptidyl Peptidase IV Activity in the Dimorphic Fungal PathogenHistoplasma capsulatum

Aspartic Proteases of Human Pathogenic Fungi are Prospective Targets for the Generation of Novel and Effective Antifungal Inhibitors

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