scholarly journals Evaluation of P1' substrate specificity of staphylococcal SplB protease.

2014 ◽  
Vol 61 (1) ◽  
Author(s):  
Katarzyna Pustelny ◽  
Natalia Stach ◽  
Benedykt Wladyka ◽  
Adam Dubin ◽  
Grzegorz Dubin
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Substrate Specificity ◽  
Kinetic Data ◽  
Proteolytic Enzymes ◽  
Physiological Role ◽  
Human Pathogen ◽  
Extracellular Proteases ◽  
Hydrolysis Of

Staphylococcus aureus is a dangerous human pathogen characterized by growing antibiotic resistance. Virulence of S. aureus relies on a variety of secreted and cell surface associated virulence factors among which certain proteolytic enzymes play an important role. Amid staphylococcal extracellular proteases, those encoded by the spl operon remain poorly characterized, both in terms of enzymology and their physiological role. Initial data demonstrated that Spl proteases exhibit restricted substrate specificity. This study describes development of convenient protein FRET substrates for SplB protease and characterization of the substrate preference of the protease at the P1' position. Kinetic data on hydrolysis of a panel of substrates substituted at the said position is provided.

Phylogeny Characterization of Seb Gene Encoding Enterotoxins in Staphylococcus aureus Isolated from Raw Milk and Cheese

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Fatima N. Aziz ◽  
Laith Abdul Hassan Mohammed-Jawad
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Raw Milk ◽  
Staphylococcal Enterotoxin B ◽  
Human Pathogen ◽  
Conventional Pcr ◽  
Biochemical Tests ◽  
Specific Primers ◽  
Gene Encoding

Food poisoning due to the bacteria is a big global problem in economically and human's health. This problem refers to an illness which is due to infection or the toxin exists in nature and the food that use. Milk is considered a nutritious food because it contains proteins and vitamins. The aim of this study is to detect and phylogeny characterization of staphylococcal enterotoxin B gene (Seb). A total of 200 milk and cheese samples were screened. One hundred ten isolates of Staphylococcus aureus pre-confirmed using selective and differential media with biochemical tests. Genomic DNA was extracted from the isolates and the SEB gene detects using conventional PCR with specific primers. Three staphylococcus aureus isolates were found to be positive for Seb gene using PCR and confirmed by sequencing. Sequence homology showed variety range of identity starting from (100% to 38%). Phylogenetic tree analyses show that samples (6 and 5) are correlated with S. epidermidis. This study discovered that isolates (A6-RLQ and A5-RLQ) are significantly clustered in a group with non- human pathogen Staphylococcus agnetis.

scholarly journals Comparative studies on O-acetylhomoserine sulfhydrylase: physiological role and characterization of the Aspergillus nidulans enzyme.

1993 ◽  
Vol 40 (3) ◽  
pp. 421-428 ◽  
Author(s):  
J Brzywczy ◽  
S Yamagata ◽  
A Paszewski
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Substrate Specificity ◽  
Aspergillus Nidulans ◽  
Comparative Studies ◽  
Alternative Pathway ◽  
Physiological Role ◽  
Oligomeric Protein ◽  
Cysteine Synthesis ◽  
Sulfhydryl Compounds

O-acetylhomoserine sulfhydrylase (OAH SHLase) from Aspergillus nidulans is an oligomeric protein with a broad substrate specificity with regard to sulfhydryl compounds. As its Saccharomyces cerevisiae counterpart the enzyme also reacts with O-acetylserine and is inhibited by carbonyl reagents but not by antiserum raised against the yeast enzyme. In contrast to Saccharomyces cerevisiae the enzyme is not essential for Aspergillus nidulans as indicated by the completely prototrophic phenotype of OAH SHLase-negative mutants. Its major physiological role in Aspergillus nidulans seems to be recycling of the thiomethyl group of methylthio-adenosine but it is also a constituent of the alternative pathway of cysteine synthesis.

scholarly journals Thermosensitive PBP2a requires extracellular folding factors PrsA and HtrA1 for Staphylococcus aureus MRSA β-lactam resistance

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Mélanie Roch ◽  
Emmanuelle Lelong ◽  
Olesya O. Panasenko ◽  
Roberto Sierra ◽  
Adriana Renzoni ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Protein Folding ◽  
Antibiotic Resistance ◽  
Active Site ◽  
Complete Loss ◽  
Folding Pathway ◽  
Human Pathogen ◽  
Clinical Challenge ◽  
Aggregation Activity ◽  
Horizontal Acquisition

AbstractStaphylococcus aureus is a major human pathogen and represents a clinical challenge because of widespread antibiotic resistance. Methicillin resistant Staphylococcus aureus (MRSA) is particularly problematic and originates by the horizontal acquisition of mecA encoding PBP2a, an extracellular membrane anchored transpeptidase, which confers resistance to β-lactam antibiotics by allosteric gating of its active site channel. Herein, we show that dual disruption of PrsA, a lipoprotein chaperone displaying anti-aggregation activity, together with HtrA1, a membrane anchored chaperone/serine protease, resulted in severe and synergistic attenuation of PBP2a folding that restores sensitivity to β-lactams such as oxacillin. Purified PBP2a has a pronounced unfolding transition initiating at physiological temperatures that leads to irreversible precipitation and complete loss of activity. The concordance of genetic and biochemical data highlights the necessity for extracellular protein folding factors governing MRSA β-lactam resistance. Targeting the PBP2a folding pathway represents a particularly attractive adjuvant strategy to combat antibiotic resistance.

Characterization of the Serratia marcescens SdeCDE multidrug efflux pump studied via gene knockout mutagenesis

2008 ◽  
Vol 54 (5) ◽  
pp. 411-416 ◽  
Author(s):  
Sanela Begic ◽  
Elizabeth A. Worobec
Keyword(s):  
Antibiotic Resistance ◽  
Substrate Specificity ◽  
Serratia Marcescens ◽  
Efflux Pump ◽  
Gene Knockout ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Active Efflux ◽  
Major Mechanism

Serratia marcescens is an important nosocomial agent having high antibiotic resistance. A major mechanism for S. marcescens antibiotic resistance is active efflux. To ascertain the substrate specificity of the S. marcescens SdeCDE efflux pump, we constructed pump gene deletion mutants. sdeCDE knockout strains showed no change in antibiotic susceptibility in comparison with the parental strains for any of the substrates, with the exception of novobiocin. In addition, novobiocin was the only antibiotic to be accumulated by sdeCDE-deficient strains. Based on the substrates used in our study, we conclude that SdeCDE is a Resistance–Nodulation–Cell Division family pump with limited substrate specificity.

Characterization of staphylococci contaminating automated teller machines in Hong Kong

2011 ◽  
Vol 140 (8) ◽  
pp. 1366-1371 ◽  
Author(s):  
M. ZHANG ◽  
M. O'DONONGHUE ◽  
M. V. BOOST
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Benzalkonium Chloride ◽  
Tetracycline Resistance ◽  
Chlorhexidine Digluconate ◽  
Coagulase Negative Staphylococci ◽  
Automated Teller Machines ◽  
Resistance Determinants

SUMMARYEnvironmental staphylococcal contamination was investigated by culture of 400 automated teller machines (ATMs). Isolates were characterized for antibiotic and antiseptic susceptibility, carriage of antiseptic resistance genes (QAC genes), and spa types. MRSA, which was similar to local clinical isolates, was present on two (0·5%) of the 62 (15·5%) ATMs that yielded Staphylococcus aureus. QAC genes were more common in coagulase-negative staphylococci (qacA/B 26·0%, smr 14%) than S. aureus (11·3% qacA/B, 1·6% smr). QAC-positive isolates had significantly higher minimum inhibitory concentrations/minimum bactericidal concentrations to benzalkonium chloride and chlorhexidine digluconate. QAC gene presence was significantly associated with methicillin and tetracycline resistance. Survival of staphylococci, including MRSA, on common access sites may be facilitated by low disinfectant concentrations, which select for disinfectant-tolerant strains, while co-selecting for antibiotic-resistance determinants. Disinfection procedures should be performed correctly to help prevent spread of resistant pathogens from reservoirs in the community.

THE PROTEOLYTIC ENZYMES OF MICROORGANISMS: III. SOME CHARACTERISTICS OF EXTRACELLULAR PROTEASES PRODUCED IN SUBMERGED CULTURE

1950 ◽  
Vol 28c (6) ◽  
pp. 600-612 ◽  
Author(s):  
W. B. McConnell
Keyword(s):  
Low Temperatures ◽  
Free Amino ◽  
Submerged Culture ◽  
Culture Medium ◽  
Proteolytic Enzymes ◽  
Amino Groups ◽  
Extracellular Proteases ◽  
Egg Albumin ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of

Some of the general characteristics of the proteases liberated into the culture medium by molds and actinomycetes grown in submerged culture have been studied. Species of Alternaria, Streptomyces, Mortierella, and Gliocladium were used. The enzymes resemble trypsin in that they are most active at a pH slightly above 7 and are inhibited by a preparation of egg albumin. They are stable at low temperatures but suffer marked losses in activity when stored for 16 hr. above 40 °C. The most rapid hydrolysis of gelatin occurs at temperatures between 40 °C. and 50 °C. The enzymes from different organisms show definite differences with respect to their ability to attack different proteins, gelatin and casein being in general the most readily digested. The protease systems from different organisms also vary with respect to the extent to which they can digest gelatin; some enzymes are able to release about three times as many amino groups from gelatin as others. The limit of the hydrolysis is not dependent upon substrate concentration but is slightly affected by the concentration of enzyme. The enzymes were effective in liberating free amino acids from gelatin.

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