Functional characterization of cell-wall-associated protein WapA in Streptococcus mutans

Zhu, Lin; Kreth, Jens; Cross, Sarah E.; Gimzewski, James K.; Shi, Wenyuan; Qi, Fengxia

doi:10.1099/mic.0.28883-0

Cited by 61 publications

(51 citation statements)

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“…in vivo and in situ conditions and has been used to determine the mechanical properties and molecular forces of bacterial cells Schär-Zammaretti & Ubbink, 2003a, b;van der Mei et al, 2000;Zhu et al, 2006). The force-measuring aspect of AFM unveils the inter-and intra-molecular forces (van der Aa et al, 2001) through recording the force-displacement curves as illustrated by the schematic in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Mechanical properties of macromolecules at the microbial surface are commonly probed by studying the tip-cell interactions observed in force spectroscopy experiments (van der Aa et al, 2001). Tip-cell-surface transient and local interactions serve as a reasonable model for probing adhesive properties at the surface of microbial cells (Pelling et al, 2005;van der Aa et al, 2001;Zhu et al, 2006). This Table 1.…”

Section: Discussionmentioning

confidence: 99%

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Nanomechanical properties of glucans and associated cell-surface adhesion of Streptococcus mutans probed by atomic force microscopy under in situ conditions

et al. 2007

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This study used atomic force microscopy (AFM) to probe the local cell-surface interactions associated with the glucan polymers of Streptococcus mutans, the macromolecules most commonly attributed to the virulence of this microbe. In situ force spectroscopy was used to quantitatively probe and correlate cell-surface adhesion and dynamics with S. mutans UA140 wild-type and five glucosyltransferase mutants. Adhesion between the tooth surface and S. mutans is largely mediated by glucan production from sucrose via three glucosyltransferases (Gtfs; GtfB, GtfC and GtfD). To monitor the contribution of these particular Gtfs, isogenic mutants of S. mutans were constructed by specific gene inactivation and compared to the wild-type under sucrose and non-sucrose conditions. We report direct measurement of the mechanical properties associated with glucan macromolecules demonstrating that the local adhesion strength increases in a time-dependent process, with a decrease in the average number of rupture events. This finding suggests that S. mutans attaches mainly through glucans to surfaces in the presence of sucrose. In addition, a possible role of the Gtf proteins in sucrose-independent attachment is supported by the decreased adhesion properties of the GtfBCD mutant compared to the wild-type.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Nanomechanical properties of glucans and associated cell-surface adhesion of Streptococcus mutans probed by atomic force microscopy under in situ conditions

et al. 2007

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“…Interestingly, the expression of one ortholog of spxA (SMU.2084c) that encodes a transcriptional regulator known to positively regulate genes in response to oxidative stress (41) was increased about 1.5-fold, whereas SMU.1548c, encoding a histidine kinase of a TCS, was downregulated approximately 30%. Interestingly, the ackA mutant exhibited a 2-fold increase in the level of transcription of wapA (SMU.987), encoding a cell wall-associated protein implicated in sucrose-independent aggregation and biofilm formation (42). Previously, a wapA mutant of S. mutans UA140 was shown to have substantially impaired biofilm formation under low-sucrose conditions (42).…”

Section: Figmentioning

confidence: 99%

“…Interestingly, the ackA mutant exhibited a 2-fold increase in the level of transcription of wapA (SMU.987), encoding a cell wall-associated protein implicated in sucrose-independent aggregation and biofilm formation (42). Previously, a wapA mutant of S. mutans UA140 was shown to have substantially impaired biofilm formation under low-sucrose conditions (42). These changes in expression of wapA and spx are thus consistent with the observed alterations in biofilm formation and oxidative stress tolerance, respectively, by the ackA mutant.…”

Section: Figmentioning

confidence: 99%

Genetics and Physiology of Acetate Metabolism by the Pta-Ack Pathway of Streptococcus mutans

Kim

Ahn

Burne

2015

Appl Environ Microbiol

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In the dental caries pathogen Streptococcus mutans, phosphotransacetylase (Pta) catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate (AcP), which can be converted to acetate by acetate kinase (Ack), with the concomitant generation of ATP. A ⌬ackA mutant displayed enhanced accumulation of AcP under aerobic conditions, whereas little or no AcP was observed in the ⌬pta or ⌬pta ⌬ackA mutant. The ⌬pta and ⌬pta ⌬ackA mutants also had diminished ATP pools compared to the size of the ATP pool for the parental or ⌬ackA strain. Surprisingly, when exposed to oxidative stress, the ⌬pta ⌬ackA strain appeared to regain the capacity to produce AcP, with a concurrent increase in the size of the ATP pool compared to that for the parental strain. The ⌬ackA and ⌬pta ⌬ackA mutants exhibited enhanced (p)ppGpp accumulation, whereas the strain lacking Pta produced less (p)ppGpp than the wild-type strain. The ⌬ackA and ⌬pta ⌬ackA mutants displayed global changes in gene expression, as assessed by microarrays. All strains lacking Pta, which had defects in AcP production under aerobic conditions, were impaired in their abilities to form biofilms when glucose was the growth carbohydrate. Collectively, these data demonstrate the complex regulation of the Pta-Ack pathway and critical roles for these enzymes in processes that appear to be essential for the persistence and pathogenesis of S. mutans. Streptococcus mutans is a facultatively anaerobic, Gram-positive bacterium with fermentative metabolism. Human dental caries is associated with increased proportions of multiple acid-tolerant species in tooth biofilms, but S. mutans shows a particularly strong association with the initiation and progression of this common infectious disease (1, 2). The pathogenic potential of S. mutans is highly dependent on its ability to form biofilms, to use a variety of carbohydrates to produce organic acids that dissolve tooth mineral, and to tolerate stresses commonly encountered in oral biofilms. In particular, tolerance of a variety of reactive oxygen species (ROS), including superoxide ions and hydrogen peroxide, is considered critical for S. mutans to overcome antagonism by oral commensals and host defenses (3, 4).S. mutans has a partial tricarboxylic acid (TCA) cycle and lacks cytochromes, so the primary route for ATP generation by this organism is through the Embden-Meyerhof-Parnas pathway (4-7). Under anaerobic conditions and with growth in the presence of an excess of a preferred carbohydrate, the pyruvate generated by glycolysis is acted on by lactate dehydrogenase (LDH), which is allosterically activated by fructose-1,6-bisphosphate (F-1,6-BP), to produce lactate and regenerate NAD (4, 8). If carbohydrate is limiting, S. mutans produces a pyruvate formate lyase enzyme, which converts pyruvate to acetyl coenzyme A (acetyl-CoA) and formate (Fig. 1). However, the pyruvate formate lyase (PFL) enzyme of S. mutans is inactivated by oxygen, so under aerobic conditions and if catabolite repression is alleviated (M. Watts and R. A....

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“…To validate the results of the microarray data, 10 randomly selected genes (Table 2) were subjected in triplicate to quantitative RT-PCR utilizing Sybr green detection in a Rotor Gene 6000 (Corbett) (75). For each sample (WT, ⌬310 mutant, and WT/Zn 2ϩ ), 2 g of total RNA was used for first-strand cDNA synthesis with a commercial RT kit (Promega) as recommended by the manufacturer, and the primers (Table 2) were designed according to the published genomic sequence of 05ZYH33 (8).…”

Section: Vol 190 2008 Functional Definition and Regulation Of Zur Imentioning

confidence: 99%

Functional Definition and Global Regulation of Zur, a Zinc Uptake Regulator in a Streptococcus suis Serotype 2 Strain Causing Streptococcal Toxic Shock Syndrome

Feng

Zhang

et al. 2008

J Bacteriol

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Zinc is an essential trace element for all living organisms and plays pivotal roles in various cellular processes. However, an excess of zinc is extremely deleterious to cells. Bacteria have evolved complex machineries (such as efflux/influx systems) to control the concentration at levels appropriate for the maintenance of zinc homeostasis in cells and adaptation to the environment. The Zur (zinc uptake regulator) protein is one of these functional members involved in the precise control of zinc homeostasis. Here we identified a zur homologue designated 310 from Streptococcus suis serotype 2, strain 05ZYH33, a highly invasive isolate causing streptococcal toxic shock syndrome. Biochemical analysis revealed that the protein product of gene 310 exists as a dimer form and carries zinc ions. An isogenic gene replacement mutant of gene 310, the ⌬310 mutant, was obtained by homologous recombination. Physiological tests demonstrated that the ⌬310 mutant is specifically sensitive to Zn 2؉ , while functional complementation of the ⌬310 mutant can restore its duration capability, suggesting that 310 is a functional member of the Zur family. Two-dimensional electrophoresis indicated that nine proteins in the ⌬310 mutant are overexpressed in comparison with those in the wild type. DNA microarray analyses suggested that 121 genes in the ⌬310 mutant are affected, of which 72 genes are upregulated and 49 are downregulated. The transcriptome of S. suis serotype 2 with high Zn 2؉ concentrations also showed 117 differentially expressed genes, with 71 upregulated and 46 downregulated. Surprisingly, more than 70% of the genes differentially expressed in the ⌬310 mutant were the same as those in S. suis serotype 2 that were differentially expressed in response to high Zn 2؉ concentration, consistent with the notion that 310 is involved in zinc homeostasis. We thus report for the first time a novel zinc-responsive regulator, Zur, from Streptococcus suis serotype 2.Streptococcus suis 2 is a gram-positive pathogenic bacterium capable of infecting both piglets and humans and causing serious diseases such as arthritis, meningitis, and septicemia (58). It has spread to nearly 20 countries, resulting in more than 400 human cases of severe infection worldwide (38). In particular, two recent outbreaks (in 1998 and 2005) of severe human S. suis serotype 2 infections in China were characterized by streptococcal toxic shock syndrome, implying that highly invasive variants of S. suis serotype 2 might be emerging in Asia (63,72). Virulence factors related to the pathogenesis of S. suis serotype 2 have been partially elucidated and include capsular polysaccharide (56), suilysin (37), muraminidase-released protein (42), and extracellular factor (59). Very recently, our group (8) reported the whole genome sequences of two virulent S. suis serotype 2 isolates (05ZYH33 and 98HAH12).Similar to other transition metals such as iron, manganese,

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Functional characterization of cell-wall-associated protein WapA in Streptococcus mutans

Cited by 61 publications

References 40 publications

Nanomechanical properties of glucans and associated cell-surface adhesion of Streptococcus mutans probed by atomic force microscopy under in situ conditions

Nanomechanical properties of glucans and associated cell-surface adhesion of Streptococcus mutans probed by atomic force microscopy under in situ conditions

Genetics and Physiology of Acetate Metabolism by the Pta-Ack Pathway of Streptococcus mutans

Functional Definition and Global Regulation of Zur, a Zinc Uptake Regulator in a Streptococcus suis Serotype 2 Strain Causing Streptococcal Toxic Shock Syndrome

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