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Full-Text Articles in Medicine and Health Sciences

Mgra Represses Biofilm Formation In Staphylococcus Aureus, Maria P. Trotonda, Sandeep Tamber, Guido Memmi, Ambrose L. Cheung Oct 2008

Mgra Represses Biofilm Formation In Staphylococcus Aureus, Maria P. Trotonda, Sandeep Tamber, Guido Memmi, Ambrose L. Cheung

Dartmouth Scholarship

MgrA is a pleiotropic regulator that controls autolysis, virulence, and efflux pump activity in Staphylococcus aureus. We recently found that mgrA mutants of strains RN6390, SH1000, and MW2 also displayed enhanced biofilm formation compared with their respective parents. The biofilms formed by mgrA mutants of RN6390 and MW2 are independent of sigB and ica loci, two genetic elements that have been previously associated with biofilm formation in S. aureus. Biofilms formed by mgrA mutants are dependent on the expression of surface proteins mediated by the sortase gene srtA. Extracellular DNA was also a crucial component of the early biofilm of …


Staphylococcus Aureus Pbp4 Is Essential For Β-Lactam Resistance In Community-Acquired Methicillin-Resistant Strains, G Memmi, S R. Filipe, M G. Pinho, Z Fu, Ambrose Cheung Aug 2008

Staphylococcus Aureus Pbp4 Is Essential For Β-Lactam Resistance In Community-Acquired Methicillin-Resistant Strains, G Memmi, S R. Filipe, M G. Pinho, Z Fu, Ambrose Cheung

Dartmouth Scholarship

Recent cases of infections caused by community-acquired methicillin-resistant Staphylococcus aureus (MRSA) (CA-MRSA) strains in healthy individuals have raised concerns worldwide. CA-MRSA strains differ from hospital-acquired MRSAs by virtue of their genomic background and increased virulence in animal models.


Repression Of Hla By Rot Is Dependent On Sae In Staphylococcus Aureus, Dongmei Li, Ambrose Cheung Jan 2008

Repression Of Hla By Rot Is Dependent On Sae In Staphylococcus Aureus, Dongmei Li, Ambrose Cheung

Dartmouth Scholarship

The regulatory locus sae is a two-component system in Staphylococcus aureus that regulates many important virulence factors, including alpha-toxin (encoded by hla) at the transcriptional level. The SarA homologs Rot and SarT were previously shown to be repressors of hla in selected S. aureus backgrounds. To delineate the interaction of rot and sae and the contribution of sarT to hla expression, an assortment of rot and sae isogenic single mutants, a rot sae double mutant, and a rot sae sarT markerless triple mutant were constructed from wild-type strain COL. Using Northern blot analysis and transcriptional reporter gene green fluorescent protein, …