Biomedical subjects

Robin S Simmonds

Publications and source records attributed to Robin S Simmonds.

6 recordsLinked to original sources

PubMed2004

The streptococcolytic enzyme zoocin A is a penicillin-binding protein.

Zoocin A is a streptococcolytic enzyme produced by Streptococcus equi subsp. zooepidemicus 4881 that has an unknown site of action on the peptidoglycans of susceptible organisms. Analysis of a mutant strain in which the genes for zoocin A and resistance to zoocin A were inactivated revealed that this strain was more susceptible to beta-lactam antibiotics than the parental organism. Purified zoocin A had weak beta-lactamase activity, bound radioactive penicillin covalently, and its streptococcolytic activity was inhibited by penicillin. Thus, zoocin A is a penicillin-binding protein and presumably is a D-alanyl endopeptidase.

Anti-Bacterial Agents↗

PubMed2004

NMR evidence for independent domain structures in zoocin A, an antibacterial exoenzyme.

NMR was used to obtain spectroscopic evidence supporting a two domain model for zoocin A in which an N-terminal catalytic domain is linked by a threonine-proline rich linker to a target recognition domain responsible for recognizing the cell wall of bacteria susceptible to the bacteriolytic action of the enzyme. When cloned and separately expressed, each domain retains the folding found in the whole enzyme. Additionally, spectroscopy suggests that the target recognition domain has a conformation typical of a soluble globular protein, while the catalytic domain aggregates at low millimolar concentrations.

Anti-Bacterial Agents↗

PubMed2004

Evaluation of porB PCR-amplicon restriction endonuclease analysis as a method to determine porB variable-region sequences in nonserotypeable meningococci.

porB PCR-amplicon restriction endonuclease analysis is a rapid, simple method developed to assess porB variation in nonserotypeable meningococci isolated during New Zealand's epidemic of meningococcal disease. Most nonserotypeable meningococci isolated between 1990 and 1999 inclusively either were type 4 (40.5%) or contained the porB variable region 1 (VR1)-19, VR2-D, VR3-7, and VR4-14a sequences (45.1%).

Amino Acid Sequence↗

PubMed2004

Multilocus restriction typing method to predict the sequence type of meningococci.

A multilocus restriction typing (MLRT) method was developed to reduce the number of sequencing reactions required to determine the clonal relationships among serogroup B meningococci causing an epidemic in New Zealand. MLRT was a rapid, simple, and inexpensive method, and the results had an excellent correlation with multilocus sequence typing results.

Alleles↗

PubMed2004

Development of a laboratory scale clean-in-place system to test the effectiveness of "natural" antimicrobials against dairy biofilms.

A laboratory scale system, partially reproducing dairy plant conditions, was developed to quantify the effectiveness of chlorine and alternative sanitizers in reducing the number of viable bacteria attached to stainless steel surfaces. Stainless steel tubes fouled in a continuous flow reactor were exposed to a standard clean-in-place regime (water rinse, 1% sodium hydroxide at 70 degrees C for 10 min, water rinse, 0.8% nitric acid at 70 degrees C for 10 min, water rinse) followed by exposure to either chlorine (200 ppm) or combinations of nisin (500 ppm), lauricidin (100 ppm), and the lactoperoxidase system (LPS) (200 ppm) for 10 min or 2, 4, 8, 18, or 24 h. There was significant variation in the effectiveness of the alkaline-acid wash steps in reducing cell numbers (log reduction between 0 and 2). Following a 10-min treatment, none of the sanitizers significantly reduced the number of attached cells. Two hours of exposure to chlorine, nisin + the LPS, or lauricidin + the LPS achieved 2.8, 2.2, and 1.6 log reductions, respectively. Exposure times > 2 h did not further decrease the number of viable bacteria attached to the stainless steel. The effectiveness of combinations of nisin, lauricidin, and the LPS was similar to that of chlorine (P > 0.05), and these sanitizers could be used to decontaminate the surfaces of small-volume or critical hard-to-clean milk processing equipment.

Animals↗

PubMed2003

Expression of the genes for lysostaphin and lysostaphin resistance in streptococci.

To determine if the genes for lysostaphin endopeptidase (end) and lysostaphin resistance (epr) function in streptococci, we transferred these genes from Staphylococcus simulans biovar staphylolyticus into two strains of Streptococcus equi subsp. zooepidemicus. The end-containing streptococci were able to produce and process proendopeptidase. Strains containing epr were more resistant to lysis by the streptococcolytic enzyme zoocin A and amino acid analysis of the peptidoglycans of the epr-containing streptococci revealed insertion of serines in their cross bridges. This is the first report of the transfer of a femABX-like immunity factor resulting in a physiologically useful effect in a different genus.

Bacterial Proteins↗