TY - JOUR
T1 - Deficiency of RgpG causes major defects in cell division and biofilm formation, and deficiency of LytR-CpsAPsr family proteins leads to accumulation of cell wall antigens in culture medium by Streptococcus mutans
AU - De, Arpan
AU - Liao, Sumei
AU - Bitoun, Jacob P.
AU - Roth, Randy
AU - Beatty, Wandy L.
AU - Wu, Hui
AU - Wen, Zezhang T.
N1 - Funding Information:
We thank Alexander H. Rickard at the University of Michigan for kindly providing us with the S. mutans whole-cell antiserum. This work was supported in part by NIH/NIDCR grant DE19452 to Z.T.W. and H.W.
Publisher Copyright:
© 2017 American Society for Microbiology.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - Streptococcus mutans is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen. S. mutans strains deficient in rgpG, encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The rgpG deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the rgpG mutant existed primarily in chains of swollen, "squarish" dividing cells. Deficiency of rgpG also causes significant reduction in biofilm formation (P < 0.01). Double and triple mutants with deficiency in brpA and/or psr, genes coding for the LytR-CpsA-Psr family proteins BrpA and Psr, which were previously shown to play important roles in cell envelope biogenesis, were constructed using the rgpG mutant. There were no major differences in growth rates between the wild-type strain and the rgpG brpA and rgpG psr double mutants, but the growth rate of the rgpG brpA psr triple mutant was reduced drastically (P < 0.001). Under transmission electron microscopy, both double mutants resembled the rgpG mutant, while the triple mutant existed as giant cells with multiple asymmetric septa. When analyzed by immunoblotting, the rgpG mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the brpA and psr single mutants. These results suggest that RgpG in S. mutans plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope.
AB - Streptococcus mutans is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen. S. mutans strains deficient in rgpG, encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The rgpG deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the rgpG mutant existed primarily in chains of swollen, "squarish" dividing cells. Deficiency of rgpG also causes significant reduction in biofilm formation (P < 0.01). Double and triple mutants with deficiency in brpA and/or psr, genes coding for the LytR-CpsA-Psr family proteins BrpA and Psr, which were previously shown to play important roles in cell envelope biogenesis, were constructed using the rgpG mutant. There were no major differences in growth rates between the wild-type strain and the rgpG brpA and rgpG psr double mutants, but the growth rate of the rgpG brpA psr triple mutant was reduced drastically (P < 0.001). Under transmission electron microscopy, both double mutants resembled the rgpG mutant, while the triple mutant existed as giant cells with multiple asymmetric septa. When analyzed by immunoblotting, the rgpG mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the brpA and psr single mutants. These results suggest that RgpG in S. mutans plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope.
KW - Biofilm formation
KW - BrpA
KW - Cell division
KW - Cell wall antigens
KW - Dental caries
KW - LCP proteins
KW - Psr
KW - Rhamnose-glucose polysaccharides
KW - Streptococcus mutans
KW - TEM analysis
UR - http://www.scopus.com/inward/record.url?scp=85027457690&partnerID=8YFLogxK
U2 - 10.1128/AEM.00928-17
DO - 10.1128/AEM.00928-17
M3 - Article
C2 - 28687645
AN - SCOPUS:85027457690
VL - 83
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 17
M1 - e00928-17
ER -