PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-3 (3)
 

Clipboard (0)
None

Select a Filter Below

Journals
Authors
more »
Year of Publication
Document Types
1.  Selective Membrane Disruption: Mode of Action of C16G2, a Specifically Targeted Antimicrobial Peptide ▿ 
The specifically targeted antimicrobial peptide (STAMP) C16G2 was developed to target the cariogenic oral pathogen Streptococcus mutans. Because the design of this peptide was novel, we sought to better understand the mechanism through which it functioned. Compared to antimicrobial peptides (AMPs) with wide spectra of activity, the STAMP C16G2 has demonstrated specificity for S. mutans in a mixed-culture environment, resulting in the complete killing of S. mutans while having minimal effect on the other streptococci. In the current study, we sought to further confirm the selectivity of C16G2 and also compare its membrane activity to that of melittin B, a classical toxic AMP, in order to determine the STAMP's mechanism of cell killing. Disruption of S. mutans cell membranes by C16G2 was demonstrated by increased SYTOX green uptake and ATP efflux from the cells similar to those of melittin B. Treatment with C16G2 also resulted in a loss of membrane potential as measured by DiSC(3)5 fluorescence. In comparison, the individual moieties of C16G2 demonstrated no specificity and limited antimicrobial activity compared to those of the STAMP C16G2. The data suggest that C16G2 has a mechanism of action similar to that of traditional AMPs and kills S. mutans through disruption of the cell membrane, allowing small molecules to leak out of the cell, which is followed by a loss of membrane potential and cell death. Interestingly, this membrane activity is rapid and potent against S. mutans, but not other noncariogenic oral streptococci.
doi:10.1128/AAC.00342-11
PMCID: PMC3122425  PMID: 21518845
2.  Transcriptional Profiles of Treponema denticola in Response to Environmental Conditions 
PLoS ONE  2010;5(10):e13655.
The periodontal pathogen T. denticola resides in a stressful environment rife with challenges, the human oral cavity. Knowledge of the stress response capabilities of this invasive spirochete is currently very limited. Whole genome expression profiles in response to different suspected stresses including heat shock, osmotic downshift, oxygen and blood exposure were examined. Most of the genes predicted to encode conserved heat shock proteins (HSPs) were found to be induced under heat and oxygen stress. Several of these HSPs also seem to be important for survival in hypotonic solutions and blood. In addition to HSPs, differential regulation of many genes encoding metabolic proteins, hypothetical proteins, transcriptional regulators and transporters was observed in patterns that could betoken functional associations. In summary, stress responses in T. denticola exhibit many similarities to the corresponding stress responses in other organisms but also employ unique components including the induction of hypothetical proteins.
doi:10.1371/journal.pone.0013655
PMCID: PMC2965109  PMID: 21048920
3.  Construction and Characterization of a cheA Mutant of Treponema denticola 
Journal of Bacteriology  2002;184(11):3130-3134.
The Treponema denticola cheA gene, encoding the central kinase of the general chemotaxis pathway, was analyzed for its role in chemotaxis and tissue penetration. The cheA gene was interrupted by insertion of an ermF-ermAM gene cassette. Reverse transcription-PCR confirmed that the other downstream chemotaxis genes within the same operon (cheW, cheX, and cheY) were still expressed in the cheA mutant strain. Lack of cheA resulted in decreased swarming on soft-agar swarm plates and failure to respond chemotactically to a mixture of nutrients. Behavioral analyses using video microscopy revealed that the cheA mutant exhibited coordinated cell movement. The cellular reversal frequency, however, was severely reduced, indicating that CheA in T. denticola mainly controls cellular reversal and that active chemotaxis signaling input is not required for coordination of flagellar rotation at both cell poles.
doi:10.1128/JB.184.11.3130-3134.2002
PMCID: PMC135053  PMID: 12003957

Results 1-3 (3)