Item – Theses Canada

​
OCLC number
56371135
Link(s) to full text
LAC copy
LAC copy
Author
Lackovic, Kresimir P.(Kresimir Petar),1976-
Title
Involvement of an amino acid transporter in the acid tolerance of Streptococcus mutans.
Degree
M. Sc. -- University of Toronto, 2003
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [2004]
Description
2 microfiches.
Notes
Includes bibliographical references.
Abstract
'Streptococcus mutans', an etiological agent of dental caries, can tolerate and dominate the acidic environment of carious sites (as low as pH 3.0). For this, 'S. mutans' has acid protective mechanisms. To study these mechanisms, acid-sensitive mutants, GTX-B and KLGLUP2 were created by inactivation of a gene designated 'gluP'. Computer analysis suggested that the substrate of the system was a polar amino acid. C14 amino acid transport suggested that the substrate was L-aspartate and competing substrates including glutamate and glutamine. Potassium stimulated the transport of aspartate and glutamate. Significant differences between the parent and mutants were observed in the unadapted and adapted acid tolerance response. Complete operon disruption resulted in a mutant with increased doubling time at neutral and mildly acidic pH. Addition of KPO4 to the growth medium resulted in increased growth yields in all strains. This work demonstrates that amino acid transport via this system is linked to K+ utilization and that inactivation of the system results in diminished growth rates and acid tolerance. Supported by Grant MT-15431 from The Canadian Institute of Health Research.
ISBN
0612785203
9780612785205