TY - JOUR
T1 - Neuraminidase A-exposed galactose promotes Streptococcus pneumoniae biofilm formation during colonization
AU - Blanchette, Krystle A.
AU - Shenoy, Anukul T.
AU - Milner, Jeffrey
AU - Gilley, Ryan P.
AU - McClure, Erin
AU - Hinojosa, Cecilia A.
AU - Kumar, Nikhil
AU - Daugherty, Sean C.
AU - Tallon, Luke J.
AU - Ott, Sandra
AU - King, Samantha J.
AU - Ferreira, Daniela M.
AU - Gordon, Stephen B.
AU - Tettelin, Hervé
AU - Orihuela, Carlos J.
N1 - Funding Information:
Wethank Monica Alarcon and Barbara Hunter for efforts in preparing the mouse nasal septa for scanning electron microscopy. We also thank Norberto Gonzalez-Juarbe for electron microscopy imaging assistance. This work was supported by National Institutes of Health grants AI078972 and AI114800 to C.J.O. K.A.B. received support through T32DE14318-10 and T32AI7271-24. The authors of this article have no conflicts of interest. This work, including the efforts of Carlos J. Orihuela, was funded by HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID) (AI078972 and AI114800). This work, including the efforts of Krystle A. Blanchette, was funded byHHS | NIH| National Institute of Allergy and Infectious Diseases (NIAID) (T32AI7271-24). This work, including the efforts of Krystle A. Blanchette, was funded by HHS | NIH | National Institute of Dental and Craniofacial Research (NIDCR) (T32DE14318-10).
PY - 2016
Y1 - 2016
N2 - Streptococcus pneumoniae is an opportunistic pathogen that colonizes the nasopharynx. Herein we show that carbon availability is distinct between the nasopharynx and bloodstream of adult humans: glucose is absent from the nasopharynx, whereas galactose is abundant. We demonstrate that pneumococcal neuraminidase A (NanA), which cleaves terminal sialic acid residues from host glycoproteins, exposed galactose on the surface of septal epithelial cells, thereby increasing its availability during colonization. We observed that S. pneumoniae mutants deficient in NanA and β-galactosidase A (BgaA) failed to form biofilms in vivo despite normal biofilm-forming abilities in vitro. Subsequently, we observed that glucose, sucrose, and fructose were inhibitory for biofilm formation, whereas galactose, lactose, and low concentrations of sialic acid were permissive. Together these findings suggested that the genes involved in biofilm formation were under some form of carbon catabolite repression (CCR), a regulatory network in which genes involved in the uptake and metabolism of less-preferred sugars are silenced during growth with preferred sugars. Supporting this notion, we observed that a mutant deficient in pyruvate oxidase, which converts pyruvate to acetyl-phosphate under non-CCR-inducing growth conditions, was unable to form biofilms. Subsequent comparative transcriptome sequencing (RNA-seq) analyses of planktonic and biofilm-grown pneumococci showed that metabolic pathways involving the conversion of pyruvate to acetyl-phosphate and subsequently leading to fatty acid biosynthesis were consistently upregulated during diverse biofilm growth conditions. We conclude that carbon availability in the nasopharynx impacts pneumococcal biofilm formation in vivo. Additionally, biofilm formation involves metabolic pathways not previously appreciated to play an important role.
AB - Streptococcus pneumoniae is an opportunistic pathogen that colonizes the nasopharynx. Herein we show that carbon availability is distinct between the nasopharynx and bloodstream of adult humans: glucose is absent from the nasopharynx, whereas galactose is abundant. We demonstrate that pneumococcal neuraminidase A (NanA), which cleaves terminal sialic acid residues from host glycoproteins, exposed galactose on the surface of septal epithelial cells, thereby increasing its availability during colonization. We observed that S. pneumoniae mutants deficient in NanA and β-galactosidase A (BgaA) failed to form biofilms in vivo despite normal biofilm-forming abilities in vitro. Subsequently, we observed that glucose, sucrose, and fructose were inhibitory for biofilm formation, whereas galactose, lactose, and low concentrations of sialic acid were permissive. Together these findings suggested that the genes involved in biofilm formation were under some form of carbon catabolite repression (CCR), a regulatory network in which genes involved in the uptake and metabolism of less-preferred sugars are silenced during growth with preferred sugars. Supporting this notion, we observed that a mutant deficient in pyruvate oxidase, which converts pyruvate to acetyl-phosphate under non-CCR-inducing growth conditions, was unable to form biofilms. Subsequent comparative transcriptome sequencing (RNA-seq) analyses of planktonic and biofilm-grown pneumococci showed that metabolic pathways involving the conversion of pyruvate to acetyl-phosphate and subsequently leading to fatty acid biosynthesis were consistently upregulated during diverse biofilm growth conditions. We conclude that carbon availability in the nasopharynx impacts pneumococcal biofilm formation in vivo. Additionally, biofilm formation involves metabolic pathways not previously appreciated to play an important role.
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U2 - 10.1128/IAI.00277-16
DO - 10.1128/IAI.00277-16
M3 - Article
C2 - 27481242
AN - SCOPUS:84994365019
VL - 84
SP - 2922
EP - 2932
JO - Infection and Immunity
JF - Infection and Immunity
SN - 0019-9567
IS - 10
ER -