Faculty Opinions recommendation of DiiA is a novel dimorphic cell wall protein of Streptococcus pneumoniae involved in invasive disease.

ABSTRACTStreptococcus pneumoniae(Spn) is an asymptomatic colonizer of the human nasopharynx but can also cause invasive diseases in the inner ear, meninges, lung and blood. Although various mechanisms contribute to the effective clearance ofSpn, opsonophagocytosis by neutrophils is perhaps most critical. Upon phagocytosis,Spnis exposed to various degradative molecules, including a family of neutrophil serine proteases (NSPs) that are stored within intracellular granules. Despite the critical importance of NSPs in killingSpn, the bacterial proteins that are degraded by NSPs leading toSpndeath are still unknown. In this report, we identify a 90kDa protein in a purified cell wall (CW) preparation, aminopeptidase N (PepN) that is degraded by the NSP, neutrophil elastase (NE). Since PepN lacked a canonical signal sequence or LPxTG motif, we created a mutant expressing a FLAG tagged version of the protein and confirmed its localization to the CW compartment. We determined that not only is PepN abona fideCW protein, but also is a substrate of NE in the context of intactSpncells. Furthermore, in comparison to wild-type TIGR4Spn, a mutant strain lacking PepN demonstrated a significant hyper-resistance phenotypein vitroin the presence of purified NE as well as in opsonophagocytic assays with purified human neutrophilsex vivo. Taken together, this is the first study to demonstrate that PepN is a CW-localized protein and a substrate of NE that contributes to the effective killing ofSpnby NSPs and human neutrophils.IMPORTANCENeutrophils are innate immune cells needed to effectively clearStreptococcus pneumoniae(Spn). Neutrophil serine proteases (NSPs) are important for killing phagocytosedSpn, however, the identity of theSpnproteins that are degraded by NSPs are unknown. This study identifies aSpncell wall protein, aminopeptidase N (PepN) that is degraded by the NSP, neutrophil elastase (NE). We demonstrate that PepN is abona fidecell wall protein and mutants lacking PepN are significantly more resistant than wild-type to killing by purified NE and human neutrophils. This study demonstrates that PepN is a NE substrate and its degradation contributes to effectiveSpnkilling. By better understanding how neutrophils killSpn, we aim to inform the development of improved therapeutic interventions.

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Nasopharyngeal Colonization and Invasive Disease Are Enhanced by the Cell Wall Hydrolases LytB and LytC of Streptococcus pneumoniae

PLoS ONE ◽

10.1371/journal.pone.0023626 ◽

2011 ◽

Vol 6 (8) ◽

pp. e23626 ◽

Cited By ~ 38

Author(s):

Elisa Ramos-Sevillano ◽

Miriam Moscoso ◽

Pedro García ◽

Ernesto García ◽

Jose Yuste

Keyword(s):

Cell Wall ◽

Streptococcus Pneumoniae ◽

Invasive Disease ◽

Nasopharyngeal Colonization ◽

Cell Wall Hydrolases

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Attachment of capsular polysaccharide to the cell wall of Streptococcus pneumoniae type 2 is required for invasive disease

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0602148103 ◽

2006 ◽

Vol 103 (22) ◽

pp. 8505-8510 ◽

Cited By ~ 94

Author(s):

J. K. Morona ◽

R. Morona ◽

J. C. Paton

Keyword(s):

Cell Wall ◽

Streptococcus Pneumoniae ◽

Capsular Polysaccharide ◽

Invasive Disease

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Characterization of PIR 32, a candida albicans cell wall protein. (c2009)

10.26756/th.2009.55 ◽

2009 ◽

Author(s):

Wael G. Bahnan

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Cell Wall Protein

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The Craterostigma plantagineum protein kinase CpWAK1 interacts with pectin and integrates different environmental signals in the cell wall

Planta ◽

10.1007/s00425-021-03609-0 ◽

2021 ◽

Vol 253 (5) ◽

Author(s):

Peilei Chen ◽

Valentino Giarola ◽

Dorothea Bartels

Keyword(s):

Cell Wall ◽

Stress Responses ◽

Expression Profiles ◽

Phylogenetic Analyses ◽

Cell Wall Protein ◽

Biological Processes ◽

Environmental Signals ◽

High Affinity ◽

Craterostigma Plantagineum ◽

Receptor Kinases

Abstract Main conclusion The cell wall protein CpWAK1 interacts with pectin, participates in decoding cell wall signals, and induces different downstream responses. Abstract Cell wall-associated protein kinases (WAKs) are transmembrane receptor kinases. In the desiccation-tolerant resurrection plant Craterostigma plantagineum, CpWAK1 has been shown to be involved in stress responses and cell expansion by forming a complex with the C. plantagineum glycine-rich protein1 (CpGRP1). This prompted us to extend the studies of WAK genes in C. plantagineum. The phylogenetic analyses of WAKs from C. plantagineum and from other species suggest that these genes have been duplicated after species divergence. Expression profiles indicate that CpWAKs are involved in various biological processes, including dehydration-induced responses and SA- and JA-related reactions to pathogens and wounding. CpWAK1 shows a high affinity for “egg-box” pectin structures. ELISA assays revealed that the binding of CpWAKs to pectins is modulated by CpGRP1 and it depends on the apoplastic pH. The formation of CpWAK multimers is the prerequisite for the CpWAK–pectin binding. Different pectin extracts lead to opposite trends of CpWAK–pectin binding in the presence of Ca2+ at pH 8. These observations demonstrate that CpWAKs can potentially discriminate and integrate cell wall signals generated by diverse stimuli, in concert with other elements, such as CpGRP1, pHapo, Ca2+[apo], and via the formation of CpWAK multimers.

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Characterization and sequence analysis of a developmentally regulated putative cell wall protein gene isolated from soybean.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)47573-4 ◽

1987 ◽

Vol 262 (17) ◽

pp. 8367-8376

Author(s):

J C Hong ◽

R T Nagao ◽

J L Key

Keyword(s):

Cell Wall ◽

Sequence Analysis ◽

Protein Gene ◽

Cell Wall Protein ◽

Developmentally Regulated

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Structural and Functional Insights into Peptidoglycan Access for the Lytic Amidase LytA of Streptococcus pneumoniae

mBio ◽

10.1128/mbio.01120-13 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 31

Author(s):

Peter Mellroth ◽

Tatyana Sandalova ◽

Alexey Kikhney ◽

Francisco Vilaplana ◽

Dusan Hesek ◽

...

Keyword(s):

Cell Wall ◽

Streptococcus Pneumoniae ◽

Solution Structure ◽

Substrate Binding ◽

Substrate Recognition ◽

Lytic Activity ◽

Site Directed Mutagenesis ◽

Binding Motif ◽

Content Type ◽

Peptidoglycan Synthesis

ABSTRACT The cytosolic N-acetylmuramoyl-l-alanine amidase LytA protein of Streptococcus pneumoniae, which is released by bacterial lysis, associates with the cell wall via its choline-binding motif. During exponential growth, LytA accesses its peptidoglycan substrate to cause lysis only when nascent peptidoglycan synthesis is stalled by nutrient starvation or β-lactam antibiotics. Here we present three-dimensional structures of LytA and establish the requirements for substrate binding and catalytic activity. The solution structure of the full-length LytA dimer reveals a peculiar fold, with the choline-binding domains forming a rigid V-shaped scaffold and the relatively more flexible amidase domains attached in a trans position. The 1.05-Å crystal structure of the amidase domain reveals a prominent Y-shaped binding crevice composed of three contiguous subregions, with a zinc-containing active site localized at the bottom of the branch point. Site-directed mutagenesis was employed to identify catalytic residues and to investigate the relative impact of potential substrate-interacting residues lining the binding crevice for the lytic activity of LytA. In vitro activity assays using defined muropeptide substrates reveal that LytA utilizes a large substrate recognition interface and requires large muropeptide substrates with several connected saccharides that interact with all subregions of the binding crevice for catalysis. We hypothesize that the substrate requirements restrict LytA to the sites on the cell wall where nascent peptidoglycan synthesis occurs. IMPORTANCE Streptococcus pneumoniae is a human respiratory tract pathogen responsible for millions of deaths annually. Its major pneumococcal autolysin, LytA, is required for autolysis and fratricidal lysis and functions as a virulence factor that facilitates the spread of toxins and factors involved in immune evasion. LytA is also activated by penicillin and vancomycin and is responsible for the lysis induced by these antibiotics. The factors that regulate the lytic activity of LytA are unclear, but it was recently demonstrated that control is at the level of substrate recognition and that LytA required access to the nascent peptidoglycan. The present study was undertaken to structurally and functionally investigate LytA and its substrate-interacting interface and to determine the requirements for substrate recognition and catalysis. Our results reveal that the amidase domain comprises a complex substrate-binding crevice and needs to interact with a large-motif epitope of peptidoglycan for catalysis.

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