Date of Award

Fall 2013

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Wayne L. Hynes

Committee Member

David Gauthier

Committee Member

Emilia Oleszak

Call Number for Print

Special Collections LD4331.B46 K67 2013


Streptococcus pyogenes, group A streptococci (GAS), causes diseases ranging from asymptomatic to life threatening. Some strains of S. pyogenes produce extracellular hyaluronate lyase (HylA), a potential virulence factor. HylA is an enzyme that degrades hyaluronic acid, which is found in the extracellular matrix of human tissues. The breakdown of the host tissue contributes to the spread of infection. The hylA gene is not constitutively expressed in vitro, which implies regulation.

A proposed regulator of hyaluronate lyase expression is RegR, a LacI/GalR like protein. A vector containing disrupted regR was electro-transformed into S. pyogenes M-type 22 strain 10403. Growth characteristics of the disrupted regR mutants, R2 and R10 differed from wild type. Enzymatic activity was measured to determine the effect of RegR on hyaluronate lyase production. Enzymatic activity of hyaluronate lyase was increased in the disrupted regR mutants compared with wild type. Transcription of hylA was also measured during the early exponential growth phase of the disrupted regR mutants and wild type. The relative amount of hylA transcript in mutant R2 was greater than wild type at hour 4. R2 showed no significant difference of hylA expression compared to wild type at T=6 hr; R10 showed no difference at T=4 or 6 hr. Changes in HylA activity and hylA expression in R2 supports the hypothesis that RegR acts as a transcriptional repressor of hyaluronate lyase within S. pyogenes M-type 22 stain 10403.


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