Up-regulation of competence- but not stress-responsive proteins accompanies an altered metabolic phenotype in Streptococcus mutans biofilms.
Mature biofilm and planktonic cells of Streptococcus mutans cultured in a neutral pH environment were subjected to comparative proteome analysis. Of the 242 protein spots identified, 48 were significantly altered in their level of expression (P<0.050) or were unique to planktonic or biofilm-grown cells. Among these were four hypothetical proteins as well as proteins known to be associated with the maintenance of competence or found to possess a cin-box-like element upstream of their coding gene. Most notable among the non-responsive genes were those encoding the molecular chaperones DnaK, GroEL and GroES, which are considered to be up-regulated by sessile growth. Analysis of the rest of the proteome indicated that a number of cellular functions associated with carbon uptake and cell division were down-regulated. The data obtained were consistent with the hypothesis that a reduction in the general growth rate of mature biofilms of S. mutans in a neutral pH environment is associated with the maintenance of transformation without the concomitant stress response observed during the transient state of competence in bacterial batch cultures.
Rathsam
Catherine
C
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Eaton
Ruth E
RE
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Simpson
Christine L
CL
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Browne
Gina V
GV
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Berg
Tracey
T
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Harty
Derek W S
DWS
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
Jacques
N A
NA
Institute of Dental Research, Westmead Millennium Institute and Westmead Centre for Oral Health, PO Box 533, Wentworthville, NSW 2145, Australia.
D000222:Adaptation, Physiological / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis*; D018441:Biofilms; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013295:Streptococcus mutans / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*
D001426:Bacterial Proteins; D020543:Proteome