scholarly journals Coping with an Essential Poison: a Genetic Suppressor Analysis Corroborates a Key Function of c-di-AMP in Controlling Potassium Ion Homeostasis in Gram-Positive Bacteria

2018 ◽  
Vol 200 (12) ◽  
Author(s):  
Fabian M. Commichau ◽  
Jörg Stülke
Keyword(s):  
Streptococcus Pneumoniae ◽  
Ion Homeostasis ◽  
Second Messenger ◽  
Potassium Ion ◽  
Complex Media ◽  
Content Type ◽  
Potassium Homeostasis ◽  
Intracellular Potassium ◽  
Gram Positive Bacteria ◽  
Suppressor Analysis

ABSTRACT Cyclic di-AMP (c-di-AMP) is an important second messenger in bacteria. In most Firmicutes , the molecule is required for growth in complex media but also toxic upon accumulation. In an article on their current study, Zarrella and coworkers present a suppressor analysis of a Streptococcus pneumoniae strain that is unable to degrade c-di-AMP (T. M. Zarrella, D. W. Metzger, and G. Bai, J Bacteriol 200:e00045-18, 2018, https://doi.org/10.1128/JB.00045-18 ). Their study identifies new links between c-di-AMP and potassium homeostasis and supports the hypothesis that c-di-AMP serves as a second messenger to report about the intracellular potassium concentrations.

scholarly journals Recognition of Streptococcus pneumoniae and Muramyl Dipeptide by NOD2 Results in Potent Induction of MMP-9, Which Can Be Controlled by Lipopolysaccharide Stimulation

2014 ◽  
Vol 82 (12) ◽  
pp. 4952-4958 ◽  
Author(s):  
Marloes Vissers ◽  
Yvonne Hartman ◽  
Laszlo Groh ◽  
Dirk J. de Jong ◽  
Marien I. de Jonge ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Mononuclear Cells ◽  
Muramyl Dipeptide ◽  
Tissue Inhibitor Of Metalloproteinase ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Potent Inducer ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACTMatrix metallopeptidase 9 (MMP-9) is a protease involved in the degradation of extracellular matrix collagen. Evidence suggests that MMP-9 is involved in pathogenesis duringStreptococcus pneumoniaeinfection. However, not much is known about the induction of MMP-9 and the regulatory processes involved. We show here that the Gram-positive bacteria used in this study induced large amounts of MMP-9, in contrast to the Gram-negative bacteria that were used. An important pathogen-associated molecular pattern (PAMP) for Gram-positive bacteria is muramyl dipeptide (MDP). MDP is a very potent inducer of MMP-9 and showed a dose-dependent MMP-9 induction. Experiments using peripheral blood mononuclear cells (PBMCs) from Crohn's disease patients with nonfunctional NOD2 showed that MMP-9 induction byStreptococcus pneumoniaeand MDP is NOD2 dependent. Increasing amounts of lipopolysaccharide (LPS), an important PAMP for Gram-negative bacteria, resulted in decreasing amounts of MMP-9. Moreover, the induction of MMP-9 by MDP could be counteracted by simultaneously adding LPS. The inhibition of MMP-9 expression by LPS was found to be regulated posttranscriptionally, independently of tissue inhibitor of metalloproteinase 1 (TIMP-1), an endogenous inhibitor of MMP-9. Collectively, these data show thatStreptococcus pneumoniaeis able to induce large amounts of MMP-9. These high MMP-9 levels are potentially involved inStreptococcus pneumoniaepathogenesis.

scholarly journals The KupA and KupB Proteins of Lactococcus lactis IL1403 Are Novel c-di-AMP Receptor Proteins Responsible for Potassium Uptake

2019 ◽  
Vol 201 (10) ◽  
Author(s):  
Ingrid M. Quintana ◽  
Johannes Gibhardt ◽  
Asan Turdiev ◽  
Elke Hammer ◽  
Fabian M. Commichau ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
Lactococcus Lactis ◽  
Second Messenger ◽  
Cell Factory ◽  
Content Type ◽  
Potassium Homeostasis ◽  
Rna Molecules ◽  
High Affinity ◽  
Potassium Transporters

ABSTRACT Cyclic di-AMP (c-di-AMP) is a second messenger involved in diverse metabolic processes, including osmolyte uptake, cell wall homeostasis, and antibiotic and heat resistance. In Lactococcus lactis, a lactic acid bacterium which is used in the dairy industry and as a cell factory in biotechnological processes, the only reported interaction partners of c-di-AMP are the pyruvate carboxylase and BusR, the transcription regulator of the busAB operon for glycine betaine uptake. However, recent studies uncovered a major role of c-di-AMP in the control of potassium homeostasis, and potassium is the signal that triggers c-di-AMP synthesis. In this study, we have identified KupA and KupB, which belong to the Kup/HAK/KT family, as novel c-di-AMP binding proteins. Both proteins are high-affinity potassium transporters, and their transport activities are inhibited by binding of c-di-AMP. Thus, in addition to the well-studied Ktr/Trk potassium channels, KupA and KupB represent a second class of potassium transporters that are subject to inhibition by c-di-AMP. IMPORTANCE Potassium is an essential ion in every living cell. Even though potassium is the most abundant cation in cells, its accumulation can be toxic. Therefore, the level of potassium has to be tightly controlled. In many Gram-positive bacteria, the second messenger cyclic di-AMP plays a key role in the control of potassium homeostasis by binding to potassium transporters and regulatory proteins and RNA molecules. In the lactic acid bacterium Lactococcus lactis, none of these conserved c-di-AMP-responsive molecules are present. In this study, we demonstrate that the KupA and KupB proteins of L. lactis IL1403 are high-affinity potassium transporters and that their transport activity is inhibited by the second messenger c-di-AMP.

scholarly journals An Essential Poison: Synthesis and Degradation of Cyclic Di-AMP in Bacillus subtilis

2015 ◽  
Vol 197 (20) ◽  
pp. 3265-3274 ◽  
Author(s):  
Jan Gundlach ◽  
Felix M. P. Mehne ◽  
Christina Herzberg ◽  
Jan Kampf ◽  
Oliver Valerius ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Nitrogen Source ◽  
Second Messengers ◽  
Regulatory Protein ◽  
Control Cell ◽  
Model Organism ◽  
Second Messenger ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACTGram-positive bacteria synthesize the second messenger cyclic di-AMP (c-di-AMP) to control cell wall and potassium homeostasis and to secure the integrity of their DNA. In the firmicutes, c-di-AMP is essential for growth. The model organismBacillus subtilisencodes three diadenylate cyclases and two potential phosphodiesterases to produce and degrade c-di-AMP, respectively. Among the three cyclases, CdaA is conserved in nearly all firmicutes, and this enzyme seems to be responsible for the c-di-AMP that is required for cell wall homeostasis. Here, we demonstrate that CdaA localizes to the membrane and forms a complex with the regulatory protein CdaR and the glucosamine-6-phosphate mutase GlmM. Interestingly,cdaA,cdaR, andglmMform a gene cluster that is conserved throughout the firmicutes. This conserved arrangement and the observed interaction between the three proteins suggest a functional relationship. Our data suggest that GlmM and GlmS are involved in the control of c-di-AMP synthesis. These enzymes convert glutamine and fructose-6-phosphate to glutamate and glucosamine-1-phosphate. c-di-AMP synthesis is enhanced if the cells are grown in the presence of glutamate compared to that in glutamine-grown cells. Thus, the quality of the nitrogen source is an important signal for c-di-AMP production. In the analysis of c-di-AMP-degrading phosphodiesterases, we observed that both phosphodiesterases, GdpP and PgpH (previously known as YqfF), contribute to the degradation of the second messenger. Accumulation of c-di-AMP in agdpP pgpHdouble mutant is toxic for the cells, and the cells respond to this accumulation by inactivation of the diadenylate cyclase CdaA.IMPORTANCEBacteria use second messengers for signal transduction. Cyclic di-AMP (c-di-AMP) is the only second messenger known so far that is essential for a large group of bacteria. We have studied the regulation of c-di-AMP synthesis and the role of the phosphodiesterases that degrade this second messenger. c-di-AMP synthesis strongly depends on the nitrogen source: glutamate-grown cells produce more c-di-AMP than glutamine-grown cells. The accumulation of c-di-AMP in a strain lacking both phosphodiesterases is toxic and results in inactivation of the diadenylate cyclase CdaA. Our results suggest that CdaA is the critical diadenylate cyclase that produces the c-di-AMP that is both essential and toxic upon accumulation.

scholarly journals Cyclic di-AMP Oversight of Counter-Ion Osmolyte Pools Impacts Intrinsic Cefuroxime Resistance in Lactococcus lactis

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Huong Thi Pham ◽  
Wen Shi ◽  
Yuwei Xiang ◽  
Su Yi Foo ◽  
Manuel R. Plan ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lactococcus Lactis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Second Messenger ◽  
Cell Lysis ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Counter Ion

ABSTRACT The broadly conserved cyclic di-AMP (c-di-AMP) is a conditionally essential bacterial second messenger. The pool of c-di-AMP is fine-tuned through diadenylate cyclase and phosphodiesterase activities, and direct binding of c-di-AMP to proteins and riboswitches allows the regulation of a broad spectrum of cellular processes. c-di-AMP has a significant impact on intrinsic β-lactam antibiotic resistance in Gram-positive bacteria; however, the reason for this is currently unclear. In this work, genetic studies revealed that suppressor mutations that decrease the activity of the potassium (K+) importer KupB or the glutamine importer GlnPQ restore cefuroxime (CEF) resistance in diadenylate cyclase (cdaA) mutants of Lactococcus lactis. Metabolite analyses showed that glutamine is imported by GlnPQ and then rapidly converted to glutamate, and GlnPQ mutations or c-di-AMP negatively affects the pools of the most abundant free amino acids (glutamate and aspartate) during growth. In a high-c-di-AMP mutant, GlnPQ activity could be increased by raising the internal K+ level through the overexpression of a c-di-AMP-insensitive KupB variant. These results demonstrate that c-di-AMP reduces GlnPQ activity and, therefore, the level of the major free anions in L. lactis through its inhibition of K+ import. Excessive ion accumulation in cdaA mutants results in greater spontaneous cell lysis under hypotonic conditions, while CEF-resistant suppressors exhibit reduced cell lysis and lower osmoresistance. This work demonstrates that the overaccumulation of major counter-ion osmolyte pools in c-di-AMP-defective mutants of L. lactis causes cefuroxime sensitivity. IMPORTANCE The bacterial second messenger cyclic di-AMP (c-di-AMP) is a global regulator of potassium homeostasis and compatible solute uptake in many Gram-positive bacteria, making it essential for osmoregulation. The role that c-di-AMP plays in β-lactam resistance, however, is unclear despite being first identified a decade ago. Here, we demonstrate that the overaccumulation of potassium or free amino acids leads to cefuroxime sensitivity in Lactococcus lactis mutants partially defective in c-di-AMP synthesis. It was shown that c-di-AMP negatively affects the levels of the most abundant free amino acids (glutamate and aspartate) in L. lactis. Regulation of these major free anions was found to occur via the glutamine transporter GlnPQ, whose activity increased in response to intracellular potassium levels, which are under c-di-AMP control. Evidence is also presented showing that they are major osmolytes that enhance osmoresistance and cell lysis. The regulatory reach of c-di-AMP can be extended to include the main free anions in bacteria.

scholarly journals The Pneumococcal Type 1 Pilus Genes Are Thermoregulated and Are Repressed by a Member of the Snf2 Protein Family

2017 ◽  
Vol 199 (15) ◽  
Author(s):  
Alan Basset ◽  
Muriel Herd ◽  
Raecliffe Daly ◽  
Simon L. Dove ◽  
Richard Malley
Keyword(s):  
Streptococcus Pneumoniae ◽  
Feedback Loop ◽  
Respiratory Infections ◽  
Protein Family ◽  
Negative Regulator ◽  
Negative Regulators ◽  
Nasopharyngeal Colonization ◽  
Content Type ◽  
Gram Positive Bacteria

ABSTRACT In Streptococcus pneumoniae, the type 1 pilus is involved in many steps of pathogenesis, including adherence to epithelial cells, mediation of inflammation, escape from macrophages, and the formation of biofilms. The type 1 pilus genes are expressed in a bistable fashion with cells switching between “on” and “off” expression states. Bistable expression of these genes is due to their control by RlrA, a positive regulator subject to control by a positive-feedback loop. The type 1 pilus genes are also thought to be negatively regulated by a large number of repressors. Here we show that expression of the type 1 pilus genes is thermosensitive and switched off at growth temperatures below 31°C. We also report that the on expression state of the type 1 pilus genes is highly stable, a phenomenon which we show likely contributed to the erroneous identification of many proteins as negative regulators of these genes. Finally, we exploited the effect of low temperature on pilus gene expression to help identify SP_1523, an Snf2-type protein, as a novel negative regulator of the pilus genes. Our findings establish that the type 1 pilus genes are thermoregulated and are repressed by a member of the Snf2 protein family. They also refute the notion that these genes are controlled by 8 previously described negative regulators. IMPORTANCE Streptococcus pneumoniae is the leading cause of death from respiratory infections in children. Many bacterial factors contribute to pneumococcal virulence and nasopharyngeal colonization. The type 1 pneumococcal pilus plays an important role in mouse models and in epithelial adherence and is expressed in a bistable fashion. Here we show that the “on” state is highly stable, which may explain the prior misidentification of negative regulators of pilus expression. We also show that expression of pilus genes is thermosensitive: virtually no expression can be detected at temperatures found in the anterior nares of humans. We took advantage of this property to identify a negative regulator of pilus expression, a member of a family of proteins widely conserved across Gram-positive bacteria.

scholarly journals Induction of Efflux-Mediated Macrolide Resistance in Streptococcus pneumoniae

2011 ◽  
Vol 55 (7) ◽  
pp. 3413-3422 ◽  
Author(s):  
Scott T. Chancey ◽  
Xiaoliu Zhou ◽  
Dorothea Zähner ◽  
David S. Stephens
Keyword(s):  
Streptococcus Pneumoniae ◽  
Fold Increase ◽  
Amino Sugar ◽  
Transferase Activity ◽  
Neutral Sugar ◽  
Content Type ◽  
Cellular Targets ◽  
Gram Positive Bacteria ◽  
Exit Tunnel ◽  
Erythromycin A

ABSTRACTThe antimicrobial efflux system encoded by the operonmef(E)-melon the mobile genetic element MEGA inStreptococcus pneumoniaeand other Gram-positive bacteria is inducible by macrolide antibiotics and antimicrobial peptides. Induction may affect the clinical response to the use of macrolides. We developedmef(E)reporter constructs and a disk diffusion induction and resistance assay to determine the kinetics and basis ofmef(E)-melinduction. Induction occurred rapidly, with a >15-fold increase in transcription within 1 h of exposure to subinhibitory concentrations of erythromycin. A spectrum of environmental conditions, including competence and nonmacrolide antibiotics with distinct cellular targets, did not inducemef(E).Using 16 different structurally defined macrolides, induction was correlated with the amino sugar attached to C-5 of the macrolide lactone ring, not with the size (e.g., 14-, 15- or 16-member) of the ring or with the presence of the neutral sugar cladinose at C-3. Macrolides with a monosaccharide attached to C-5, known to block exit of the nascent peptide from the ribosome after the incorporation of up to eight amino acids, inducedmef(E)expression. Macrolides with a C-5 disaccharide, which extends the macrolide into the ribosomal exit tunnel, disrupting peptidyl transferase activity, did not induce it. The induction ofmef(E)did not require macrolide efflux, but the affinity of macrolides for the ribosome determined the availability for efflux and pneumococcal susceptibility. The induction ofmef(E)-melexpression by inducing macrolides appears to be based on specific interactions of the macrolide C-5 saccharide with the ribosome that alleviate transcriptional attenuation ofmef(E)-mel.

scholarly journals Dynamic Distribution of the SecA and SecY Translocase Subunits and Septal Localization of the HtrA Surface Chaperone/Protease during Streptococcus pneumoniae D39 Cell Division

mBio ◽  
2011 ◽  
Vol 2 (5) ◽  
Author(s):  
Ho-Ching Tiffany Tsui ◽  
Susan K. Keen ◽  
Lok-To Sham ◽  
Kyle J. Wayne ◽  
Malcolm E. Winkler
Keyword(s):  
Cell Division ◽  
Streptococcus Pneumoniae ◽  
Stationary Phase ◽  
Streptococcus Pyogenes ◽  
Phospholipid Content ◽  
Gram Positive ◽  
General Role ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Dividing Cells

ABSTRACT The Sec translocase pathway is the major route for protein transport across and into the cytoplasmic membrane of bacteria. Previous studies reported that the SecA translocase ATP-binding subunit and the cell surface HtrA protease/chaperone formed a single microdomain, termed “ExPortal,” in some species of ellipsoidal (ovococcus) Gram-positive bacteria, including Streptococcus pyogenes. To investigate the generality of microdomain formation, we determined the distribution of SecA and SecY by immunofluorescent microscopy in Streptococcus pneumoniae (pneumococcus), which is an ovococcus species evolutionarily distant from S. pyogenes. In the majority (≥75%) of exponentially growing cells, S. pneumoniae SecA (SecA Spn ) and SecY Spn located dynamically in cells at different stages of division. In early divisional cells, both Sec subunits concentrated at equators, which are future sites of constriction. Further along in division, SecA Spn and SecY Spn remained localized at mid-cell septa. In late divisional cells, both Sec subunits were hemispherically distributed in the regions between septa and the future equators of dividing cells. In contrast, the HtrA Spn homologue localized to the equators and septa of most (>90%) dividing cells, whereas the SrtA Spn sortase located over the surface of cells in no discernable pattern. This dynamic pattern of Sec distribution was not perturbed by the absence of flotillin family proteins, but was largely absent in most cells in early stationary phase and in ∆cls mutants lacking cardiolipin synthase. These results do not support the existence of an ExPortal microdomain in S. pneumoniae. Instead, the localization of the pneumococcal Sec translocase depends on the stage of cell division and anionic phospholipid content. IMPORTANCE Two patterns of Sec translocase distribution, an ExPortal microdomain in certain ovococcus-shaped species like Streptococcus pyogenes and a spiral pattern in rod-shaped species like Bacillus subtilis, have been reported for Gram-positive bacteria. This study provides evidence for a third pattern of Sec localization in the ovococcus human pathogen Streptococcus pneumoniae. The SecA motor and SecY channel subunits of the Sec translocase localize dynamically to different places in the mid-cell region during the division cycle of exponentially growing, but not stationary-phase, S. pneumoniae. Unexpectedly, the S. pneumoniae HtrA (HtrA Spn ) protease/chaperone principally localizes to cell equators and division septa. The coincident localization of SecA Spn , SecY Spn , and HtrA Spn to regions of peptidoglycan (PG) biosynthesis in unstressed, growing cells suggests that the pneumococcal Sec translocase directs assembly of the PG biosynthesis apparatus to regions where it is needed during division and that HtrA Spn may play a general role in quality control of proteins exported by the Sec translocase.

scholarly journals Making and Breaking of an Essential Poison: the Cyclases and Phosphodiesterases That Produce and Degrade the Essential Second Messenger Cyclic di-AMP in Bacteria

2018 ◽  
Vol 201 (1) ◽  
Author(s):  
Fabian M. Commichau ◽  
Jana L. Heidemann ◽  
Ralf Ficner ◽  
Jörg Stülke
Keyword(s):  
Protein Interactions ◽  
Catalytic Domain ◽  
Second Messenger ◽  
Structural Features ◽  
Protein Protein Interactions ◽  
Catalytic Core ◽  
Osmotic Adaptation ◽  
Content Type ◽  
Potassium Homeostasis ◽  
Potassium Transporters

ABSTRACT Cyclic di-AMP is a second-messenger nucleotide that is produced by many bacteria and some archaea. Recent work has shown that c-di-AMP is unique among the signaling nucleotides, as this molecule is in many bacteria both essential on one hand and toxic upon accumulation on the other. Moreover, in bacteria, like Bacillus subtilis, c-di-AMP controls a biological process, potassium homeostasis, by binding both potassium transporters and riboswitch molecules in the mRNAs that encode the potassium transporters. In addition to the control of potassium homeostasis, c-di-AMP has been implicated in many cellular activities, including DNA repair, cell wall homeostasis, osmotic adaptation, biofilm formation, central metabolism, and virulence. c-di-AMP is synthesized and degraded by diadenylate cyclases and phosphodiesterases, respectively. In the diadenylate cyclases, one type of catalytic domain, the diadenylate cyclase (DAC) domain, is coupled to various other domains that control the localization, the protein-protein interactions, and the regulation of the enzymes. The phosphodiesterases have a catalytic core that consists either of a DHH/DHHA1 or of an HD domain. Recent findings on the occurrence, domain organization, activity control, and structural features of diadenylate cyclases and phosphodiesterases are discussed in this review.

scholarly journals Bacterial Second Messenger Cyclic di-AMP Modulates the Competence State in Streptococcus pneumoniae

2019 ◽  
Vol 202 (4) ◽  
Author(s):  
Tiffany M. Zarrella ◽  
Jun Yang ◽  
Dennis W. Metzger ◽  
Guangchun Bai
Keyword(s):  
Streptococcus Pneumoniae ◽  
Stress Responses ◽  
Transformation Efficiency ◽  
Second Messenger ◽  
Stress Conditions ◽  
Dna Uptake ◽  
Content Type ◽  
Bacterial Physiology ◽  
Family Protein ◽  
Models Of Disease

ABSTRACT Streptococcus pneumoniae (the pneumococcus) is a naturally competent organism that causes diseases such as pneumonia, otitis media, and bacteremia. The essential bacterial second messenger cyclic di-AMP (c-di-AMP) is an emerging player in the stress responses of many pathogens. In S. pneumoniae, c-di-AMP is produced by a diadenylate cyclase, CdaA, and cleaved by phosphodiesterases Pde1 and Pde2. c-di-AMP binds a transporter of K+ (Trk) family protein, CabP, which subsequently halts K+ uptake via the transporter TrkH. Recently, it was reported that Pde1 and Pde2 are essential for pneumococcal virulence in mouse models of disease. To elucidate c-di-AMP-mediated transcription that may lead to changes in pathogenesis, we compared the transcriptomes of wild-type (WT) and Δpde1 Δpde2 strains by transcriptome sequencing (RNA-Seq) analysis. Notably, we found that many competence-associated genes are significantly upregulated in the Δpde1 Δpde2 strain compared to the WT. These genes play a role in DNA uptake, recombination, and autolysis. Competence is induced by a quorum-sensing mechanism initiated by the secreted factor competence-stimulating peptide (CSP). Surprisingly, the Δpde1 Δpde2 strain exhibited reduced transformation efficiency compared to WT bacteria, which was c-di-AMP dependent. Transformation efficiency was also directly related to the [K+] in the medium, suggesting a link between c-di-AMP function and the pneumococcal competence state. We found that a strain that possesses a V76G variation in CdaA produced less c-di-AMP and was highly susceptible to CSP. Deletion of cabP and trkH restored the growth of these bacteria in medium with CSP. Overall, our study demonstrates a novel role for c-di-AMP in the competence program of S. pneumoniae. IMPORTANCE Genetic competence in bacteria leads to horizontal gene transfer, which can ultimately affect antibiotic resistance, adaptation to stress conditions, and virulence. While the mechanisms of pneumococcal competence signaling cascades have been well characterized, the molecular mechanism behind competence regulation is not fully understood. The bacterial second messenger c-di-AMP has previously been shown to play a role in bacterial physiology and pathogenesis. In this study, we provide compelling evidence for the interplay between c-di-AMP and the pneumococcal competence state. These findings not only attribute a new biological function to this dinucleotide as a regulator of competence, transformation, and survival under stress conditions in pneumococci but also provide new insights into how pneumococcal competence is modulated.

scholarly journals Antibodies to Streptococcus pneumoniae Capsular Polysaccharide Enhance Pneumococcal Quorum Sensing

mBio ◽  
2011 ◽  
Vol 2 (5) ◽  
Author(s):  
Masahide Yano ◽  
Shruti Gohil ◽  
J. Robert Coleman ◽  
Catherine Manix ◽  
Liise-anne Pirofski
Keyword(s):  
Monoclonal Antibodies ◽  
Streptococcus Pneumoniae ◽  
Quorum Sensing ◽  
Direct Effect ◽  
Pneumococcal Disease ◽  
Effector Cell ◽  
Capsular Polysaccharide ◽  
Genetic Exchange ◽  
Content Type ◽  
Specific Antibodies

ABSTRACTThe use of pneumococcal capsular polysaccharide (PPS)-based vaccines has resulted in a substantial reduction in invasive pneumococcal disease. However, much remains to be learned about vaccine-mediated immunity, as seven-valent PPS-protein conjugate vaccine use in children has been associated with nonvaccine serotype replacement and 23-valent vaccine use in adults has not prevented pneumococcal pneumonia. In this report, we demonstrate that certain PPS-specific monoclonal antibodies (MAbs) enhance the transformation frequency of two differentStreptococcus pneumoniaeserotypes. This phenomenon was mediated by PPS-specific MAbs that agglutinate but do not promote opsonic effector cell killing of the homologous serotypeinvitro. Compared to the autoinducer, competence-stimulating peptide (CSP) alone, transcriptional profiling of pneumococcal gene expression after incubation with CSP and one such MAb to the PPS of serotype 3 revealed changes in the expression of competence (com)-related and bacteriocin-like peptide (blp) genes involved in pneumococcal quorum sensing. This MAb was also found to induce a nearly 2-fold increase in CSP2-mediated bacterial killing or fratricide. These observations reveal a novel, direct effect of PPS-binding MAbs on pneumococcal biology that has important implications for antibody immunity to pneumococcus in the pneumococcal vaccine era. Taken together, our data suggest heretofore unsuspected mechanisms by which PPS-specific antibodies could affect genetic exchange and bacterial viability in the absence of host cells.IMPORTANCECurrent thought holds that pneumococcal capsular polysaccharide (PPS)-binding antibodies protect against pneumococcus by inducing effector cell opsonic killing of the homologous serotype. While such antibodies are an important part of how pneumococcal vaccines protect against pneumococcal disease, PPS-specific antibodies that do not exhibit this activity but are highly protective against pneumococcus in mice have been identified. This article examines the effect of nonopsonic PPS-specific monoclonal antibodies (MAbs) on the biology ofStreptococcus pneumoniae. The results showed that in the presence of a competence-stimulating peptide (CSP), such MAbs increase the frequency of pneumococcal transformation. Further studies with one such MAb showed that it altered the expression of genes involved in quorum sensing and increased competence-induced killing or fratricide. These findings reveal a novel, previously unsuspected mechanism by which certain PPS-specific antibodies exert a direct effect on pneumococcal biology that has broad implications for bacterial clearance, genetic exchange, and antibody immunity to pneumococcus.

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