Manganese affects Streptococcus mutans virulence gene expression.
OBJECTIVE
Studies of trace metals in drinking water and tooth enamel have suggested a caries-promoting potential for manganese (Mn). Additionally, Mn has been shown to be essential for the expression of mutans streptococci virulence factors such as the glucan-binding lectin (GBL) of Streptococcus sobrinus. The Streptococcus mutans glucan-binding protein (Gbp) GbpC is the functional analogue of the S. sobrinus GBL. S. mutans Gbps have been shown to contribute to biofilm architecture and virulence. This study was undertaken to examine the effects of Mn on the transcription of genes encoding S. mutans Gbps, including gbpC, along with other critical S. mutans virulence genes.


METHODS
Microarray analyses suggested the potential for an Mn effect on Gbp genes. Further investigation of the Mn effects on selected genes was undertaken by performing Northern blots, Western blots, and RT-PCR under conditions of planktonic and biofilm growth in Mn-depleted media or in media containing 50 mircoM Mn.


RESULTS
Mn resulted in increased expression of gbpC and gtfB, and decreased expression of wapA, in both planktonic and biofilm cultures. The expression levels of gbpA and gbpD were also decreased in the presence of Mn, but only in biofilms. The expression of gtfC was increased in the presence of Mn only in planktonic cultures. The spaP gene was expressed more highly in Mn-supplemented planktonic cultures but less in Mn-supplemented biofilms.


CONCLUSIONS
Mn availability affects the expression of multiple S. mutans genes involved in adhesion and biofilm formation. Furthermore, these effects depend on the growth state of the organism.
Arirachakaran
P
P
Chulalongkorn University, Bangkok, Thailand.
Benjavongkulchai
E
E
Luengpailin
S
S
Ajdić
D
D
Banas
J A
JA
D000818:Animals; D001426:Bacterial Proteins / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002326:Cariogenic Agents / Q000494:pharmacology*; D002352:Carrier Proteins / Q000187:drug effects; D003731:Dental Caries / Q000382:microbiology; D015870:Gene Expression / Q000187:drug effects*; D005798:Genes, Bacterial / Q000187:drug effects / Q000235:genetics; D037102:Lectins / Q000187:drug effects; D008345:Manganese / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000187:drug effects; D040081:Protein Array Analysis / Q000379:methods; D012313:RNA / Q000302:isolation & purification; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D014131:Trace Elements / Q000494:pharmacology*; D014774:Virulence / Q000187:drug effects
D001426:Bacterial Proteins; D002326:Cariogenic Agents; D002352:Carrier Proteins; D037102:Lectins; D008562:Membrane Glycoproteins; C055764:S-layer proteins; D014131:Trace Elements; C082429:glucan-binding lectin, Streptococcus sobrinus; C037937:glucan-binding proteins; D008345:Manganese; D012313:RNA