scholarly journals The Presence of Two Receptor-Binding Proteins Contributes to the Wide Host Range of Staphylococcal Twort-Like Phages

2016 ◽  
Vol 82 (19) ◽  
pp. 5763-5774 ◽  
Author(s):  
Ippei Takeuchi ◽  
Keita Osada ◽  
Aa Haeruman Azam ◽  
Hiroaki Asakawa ◽  
Kazuhiko Miyanaga ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Range ◽  
Receptor Binding ◽  
Polyclonal Antibody ◽  
Binding Proteins ◽  
Host Recognition ◽  
Resistant Bacteria ◽  
Tail Fiber ◽  
Content Type ◽  
Wide Host Range

ABSTRACTThanks to their wide host range and virulence, staphylococcal bacteriophages (phages) belonging to the genusTwortlikevirus(staphylococcal Twort-like phages) are regarded as ideal candidates for clinical application forStaphylococcus aureusinfections due to the emergence of antibiotic-resistant bacteria of this species. To increase the usability of these phages, it is necessary to understand the mechanism underlying host recognition, especially the receptor-binding proteins (RBPs) that determine host range. In this study, we found that the staphylococcal Twort-like phage ΦSA012 possesses at least two RBPs. Genomic analysis of five mutant phages of ΦSA012 revealed point mutations inorf103, in a region unique to staphylococcal Twort-like phages. Phages harboring mutated ORF103 could not infectS. aureusstrains in which wall teichoic acids (WTAs) are glycosylated with α-N-acetylglucosamine (α-GlcNAc). A polyclonal antibody against ORF103 also inhibited infection by ΦSA012 in the presence of α-GlcNAc, suggesting that ORF103 binds to α-GlcNAc. In contrast, a polyclonal antibody against ORF105, a short tail fiber component previously shown to be an RBP, inhibited phage infection irrespective of the presence of α-GlcNAc. Immunoelectron microscopy indicated that ORF103 is a tail fiber component localized at the bottom of the baseplate. From these results, we conclude that ORF103 binds α-GlcNAc in WTAs, whereas ORF105, the primary RBP, is likely to bind the WTA backbone. These findings provide insight into the infection mechanism of staphylococcal Twort-like phages.IMPORTANCEStaphylococcusphages belonging to the genusTwortlikevirus(called staphylococcal Twort-like phages) are considered promising agents for control ofStaphylococcus aureusdue to their wide host range and highly lytic capabilities. Although staphylococcal Twort-like phages have been studied widely for therapeutic purposes, the host recognition process of staphylococcal Twort-like phages remains unclear. This work provides new findings about the mechanisms of host recognition of the staphylococcal Twort-like phage ΦSA012. The details of the host recognition mechanism of ΦSA012 will allow us to analyze the mechanisms of infection and expand the utility of staphylococcal Twort-like phages for the control ofS. aureus.

scholarly journals Alteromonas Myovirus V22 Represents a New Genus of Marine Bacteriophages Requiring a Tail Fiber Chaperone for Host Recognition

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Rafael Gonzalez-Serrano ◽  
Matthew Dunne ◽  
Riccardo Rosselli ◽  
Ana-Belen Martin-Cuadrado ◽  
Virginie Grosboillot ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Receptor Binding ◽  
Binding Proteins ◽  
Fluorescent Protein ◽  
Sequence Similarity ◽  
Functional Characterization ◽  
Size Exclusion ◽  
Host Recognition ◽  
Tail Fiber ◽  
Microbial Composition

ABSTRACT Marine phages play a variety of critical roles in regulating the microbial composition of our oceans. Despite constituting the majority of genetic diversity within these environments, there are relatively few isolates with complete genome sequences or in-depth analyses of their host interaction mechanisms, such as characterization of their receptor binding proteins (RBPs). Here, we present the 92,760-bp genome of the Alteromonas-targeting phage V22. Genomic and morphological analyses identify V22 as a myovirus; however, due to a lack of sequence similarity to any other known myoviruses, we propose that V22 be classified as the type phage of a new Myoalterovirus genus within the Myoviridae family. V22 shows gene homology and synteny with two different subfamilies of phages infecting enterobacteria, specifically within the structural region of its genome. To improve our understanding of the V22 adsorption process, we identified putative RBPs (gp23, gp24, and gp26) and tested their ability to decorate the V22 propagation strain, Alteromonas mediterranea PT11, as recombinant green fluorescent protein (GFP)-tagged constructs. Only GFP-gp26 was capable of bacterial recognition and identified as the V22 RBP. Interestingly, production of functional GFP-gp26 required coexpression with the downstream protein gp27. GFP-gp26 could be expressed alone but was incapable of host recognition. By combining size-exclusion chromatography with fluorescence microscopy, we reveal how gp27 is not a component of the final RBP complex but instead is identified as a new type of phage-encoded intermolecular chaperone that is essential for maturation of the gp26 RBP. IMPORTANCE Host recognition by phage-encoded receptor binding proteins (RBPs) constitutes the first step in all phage infections and the most critical determinant of host specificity. By characterizing new types of RBPs and identifying their essential chaperones, we hope to expand the repertoire of known phage-host recognition machineries. Due to their genetic plasticity, studying RBPs and their associated chaperones can shed new light onto viral evolution affecting phage-host interactions, which is essential for fields such as phage therapy or biotechnology. In addition, since marine phages constitute one of the most important reservoirs of noncharacterized genetic diversity on the planet, their genomic and functional characterization may be of paramount importance for the discovery of novel genes with potential applications.

scholarly journals A Putative Cro-Like Repressor Contributes to Arylomycin Resistance in Staphylococcus aureus

2015 ◽  
Vol 59 (6) ◽  
pp. 3066-3074 ◽  
Author(s):  
Arryn Craney ◽  
Floyd E. Romesberg
Keyword(s):  
Staphylococcus Aureus ◽  
Ex Vivo ◽  
Transcriptional Regulator ◽  
Signal Peptidase ◽  
Health Concern ◽  
Resistant Bacteria ◽  
Type I ◽  
Wall Teichoic Acid ◽  
Content Type ◽  
Wide Range

ABSTRACTAntibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogenStaphylococcus aureus. To understand the origins of the limited activity againstS. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand howS. aureusresponds to the arylomycins, we profiled the transcriptional response ofS. aureusNCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistanceex vivodemonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate howS. aureuscopes with secretion stress and how it evolves resistance to the inhibition of SPase.

scholarly journals Susceptibility of Methicillin-Resistant Staphylococcus aureus to Five Quinazolinone Antibacterials

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Sara Ceballos ◽  
Choon Kim ◽  
Yuanyuan Qian ◽  
Shahriar Mobashery ◽  
Mayland Chang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Amino Acid ◽  
Binding Proteins ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Content Type ◽  
Penicillin Binding Proteins

ABSTRACT The in vitro activities of five quinazolinone antibacterials, compounds Q1 to Q5, were tested against 210 strains of methicillin-resistant Staphylococcus aureus (MRSA). The MIC50/MIC90 values (in μg/ml) were as follows: Q1, 0.5/2; Q2, 1/4; Q3, 2/4; Q4, 0.06/0.25; and Q5, 0.125/0.5. Several strains with high MIC values (from 8 to >32 μg/ml) for some of these compounds exhibited amino acid changes in the penicillin-binding proteins, which are targeted by these antibacterials.

scholarly journals Mutant and Recombinant Phages Selected from In Vitro Coevolution Conditions Overcome Phage-Resistant Listeria monocytogenes

2020 ◽  
Vol 86 (22) ◽  
Author(s):  
Tracey Lee Peters ◽  
Yaxiong Song ◽  
Daniel W. Bryan ◽  
Lauren K. Hudson ◽  
Thomas G. Denes
Keyword(s):  
Listeria Monocytogenes ◽  
Host Range ◽  
Foodborne Pathogen ◽  
Resistant Bacteria ◽  
Phage Resistance ◽  
Short Term ◽  
Content Type ◽  
Life Threatening ◽  
The Impact

ABSTRACT Bacteriophages (phages) are currently available for use by the food industry to control the foodborne pathogen Listeria monocytogenes. Although phage biocontrols are effective under specific conditions, their use can select for phage-resistant bacteria that repopulate phage-treated environments. Here, we performed short-term coevolution experiments to investigate the impact of single phages and a two-phage cocktail on the regrowth of phage-resistant L. monocytogenes and the adaptation of the phages to overcome this resistance. We used whole-genome sequencing to identify mutations in the target host that confer phage resistance and in the phages that alter host range. We found that infections with Listeria phages LP-048, LP-125, or a combination of both select for different populations of phage-resistant L. monocytogenes bacteria with different regrowth times. Phages isolated from the end of the coevolution experiments were found to have gained the ability to infect phage-resistant mutants of L. monocytogenes and L. monocytogenes strains previously found to be broadly resistant to phage infection. Phages isolated from coinfected cultures were identified as recombinants of LP-048 and LP-125. Interestingly, recombination events occurred twice independently in a locus encoding two proteins putatively involved in DNA binding. We show that short-term coevolution of phages and their hosts can be utilized to obtain mutant and recombinant phages with adapted host ranges. These laboratory-evolved phages may be useful for limiting the emergence of phage resistance and for targeting strains that show general resistance to wild-type (WT) phages. IMPORTANCE Listeria monocytogenes is a life-threatening bacterial foodborne pathogen that can persist in food processing facilities for years. Phages can be used to control L. monocytogenes in food production, but phage-resistant bacterial subpopulations can regrow in phage-treated environments. Coevolution experiments were conducted on a Listeria phage-host system to provide insight into the genetic variation that emerges in both the phage and bacterial host under reciprocal selective pressure. As expected, mutations were identified in both phage and host, but additionally, recombination events were shown to have repeatedly occurred between closely related phages that coinfected L. monocytogenes. This study demonstrates that in vitro evolution of phages can be utilized to expand the host range and improve the long-term efficacy of phage-based control of L. monocytogenes. This approach may also be applied to other phage-host systems for applications in biocontrol, detection, and phage therapy.

scholarly journals Identification of Bacteriophages for Biocontrol of the Kiwifruit Canker Phytopathogen Pseudomonas syringae pv. actinidiae

2014 ◽  
Vol 80 (7) ◽  
pp. 2216-2228 ◽  
Author(s):  
Rebekah A. Frampton ◽  
Corinda Taylor ◽  
Angela V. Holguín Moreno ◽  
Sandra B. Visnovsky ◽  
Nicola K. Petty ◽  
...  
Keyword(s):  
Host Range ◽  
Pseudomonas Syringae ◽  
Management Strategies ◽  
Pulse Field ◽  
Resistant Bacteria ◽  
Bacterial Canker ◽  
Content Type ◽  
Narrow Host Range ◽  
Pulse Field Gel Electrophoresis ◽  
Isolation And Characterization

ABSTRACTPseudomonas syringaepv. actinidiae is a reemerging pathogen which causes bacterial canker of kiwifruit (Actinidiasp.). Since 2008, a global outbreak ofP. syringaepv. actinidiae has occurred, and in 2010 this pathogen was detected in New Zealand. The economic impact and the development of resistance inP. syringaepv. actinidiae and other pathovars against antibiotics and copper sprays have led to a search for alternative management strategies. We isolated 275 phages, 258 of which were active againstP. syringaepv. actinidiae. Extensive host range testing onP. syringaepv. actinidiae, other pseudomonads, and bacteria isolated from kiwifruit orchards showed that most phages have a narrow host range. Twenty-four were analyzed by electron microscopy, pulse-field gel electrophoresis, and restriction digestion. Their suitability for biocontrol was tested by assessing stability and the absence of lysogeny and transduction. A detailed host range was performed, phage-resistant bacteria were isolated, and resistance to other phages was examined. The phages belonged to theCaudoviralesand were analyzed based on morphology and genome size, which showed them to be representatives ofMyoviridae,Podoviridae, andSiphoviridae. Twenty-oneMyoviridaemembers have similar morphologies and genome sizes yet differ in restriction patterns, host range, and resistance, indicating a closely related group. Nine of theseMyoviridaemembers were sequenced, and each was unique. The most closely related sequenced phages were a group infectingPseudomonas aeruginosaand characterized by phages JG004 and PAK_P1. In summary, this study reports the isolation and characterization ofP. syringaepv. actinidiae phages and provides a framework for the intelligent formulation of phage biocontrol agents against kiwifruit bacterial canker.

scholarly journals JD419, a Staphylococcus aureus Phage With a Unique Morphology and Broad Host Range

2021 ◽  
Vol 12 ◽  
Author(s):  
Tingting Feng ◽  
Sebastian Leptihn ◽  
Ke Dong ◽  
Belinda Loh ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Host Range ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Complete Characterization ◽  
Resistant Bacteria ◽  
Broad Host Range ◽  
Gene Engineering ◽  
Mrsa Strains

Phage therapy represents a possible treatment option to cure infections caused by multidrug-resistant bacteria, including methicillin and vancomycin-resistant Staphylococcus aureus, to which most antibiotics have become ineffective. In the present study, we report the isolation and complete characterization of a novel phage named JD219 exhibiting a broad host range able to infect 61 of 138 clinical strains of S. aureus tested, which included MRSA strains as well. The phage JD419 exhibits a unique morphology with an elongated capsid and a flexible tail. To evaluate the potential of JD419 to be used as a therapeutic phage, we tested the ability of the phage particles to remain infectious after treatment exceeding physiological pH or temperature. The activity was retained at pH values of 6.0–8.0 and below 50°C. As phages can contain virulence genes, JD419’s complete genome was sequenced. The 45509 bp genome is predicted to contain 65 ORFs, none of which show homology to any known virulence or antibiotic resistance genes. Genome analysis indicates that JD419 is a temperate phage, despite observing rapid replication and lysis of host strains. Following the recent advances in synthetic biology, JD419 can be modified by gene engineering to remove prophage-related genes, preventing potential lysogeny, in order to be deployed as a therapeutic phage.

scholarly journals Innolysins: A novel approach to engineer endolysins to kill Gram-negative bacteria

2018 ◽  
Author(s):  
Athina Zampara ◽  
Martine C. Holst Sørensen ◽  
Dennis Grimon ◽  
Fabio Antenucci ◽  
Yves Briers ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Receptor Binding ◽  
Binding Proteins ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Proof Of Concept ◽  
Gram Negative ◽  
E Coli ◽  
Phage Receptor ◽  
Alternative Antimicrobials

ABSTRACTBacteriophage-encoded endolysins degrading the essential peptidoglycan of bacteria are promising alternative antimicrobials to handle the global threat of antibiotic resistant bacteria. However, endolysins have limited use against Gram-negative bacteria, since their outer membrane prevents access to the peptidoglycan. Here we present Innolysins, a novel concept for engineering endolysins that allows the enzymes to pass through the outer membrane, hydrolyse the peptidoglycan and kill the target bacterium. Innolysins combine the enzymatic activity of endolysins with the binding capacity of phage receptor binding proteins (RBPs). As our proof of concept, we used phage T5 endolysin and receptor binding protein Pb5, which binds irreversibly to the phage receptor FhuA involved in ferrichrome transport inEscherichia coli. In total, we constructed twelve Innolysins fusing endolysin with Pb5 or the binding domain of Pb5 with or without flexible linkers in between. While the majority of the Innolysins maintained their muralytic activity, Innolysin#6 also showed bactericidal activity againstE. colireducing the number of bacteria by 1 log, thus overcoming the outer membrane barrier. Using anE. coli fhuAdeletion mutant, we demonstrated that FhuA is required for bactericidal activity, supporting that the specific binding of Pb5 to its receptor onE. coliis needed for the endolysin to access the peptidoglycan. Accordingly, Innolysin#6 was able to kill other bacterial species that carry conserved FhuA homologs such asShigella sonneiandPseudomonas aeruginosa. In summary, the Innolysin approach expands recent protein engineering strategies allowing customization of endolysins by exploiting phage RBPs to specifically target Gram-negative bacteria.IMPORTANCEThe extensive use of antibiotics has led to the emergence of antimicrobial resistant bacteria responsible for infections causing more than 50,000 deaths per year across Europe and the US. In response, the World Health Organization has stressed an urgent need to discover new antimicrobials to control in particular Gram-negative bacterial pathogens, due to their extensive multi-drug resistance. However, the outer membrane of Gram-negative bacteria limits the access of many antibacterial agents to their targets. Here, we developed a new approach, Innolysins that enable endolysins to overcome the outer membrane by exploiting the binding specificity of phage receptor binding proteins. As proof of concept, we constructed Innolysins againstE. coliusing the endolysin and the receptor binding protein of phage T5. Given the rich diversity of phage receptor binding proteins and their different binding specificities, our proof of concept paves the route for creating an arsenal of pathogen specific alternative antimicrobials.

scholarly journals A Tail Fiber Protein and a Receptor-Binding Protein Mediate ICP2 Bacteriophage Interactions with Vibrio cholerae OmpU

2021 ◽  
Author(s):  
Andrea N.W. Lim ◽  
Minmin Yen ◽  
Kimberley D. Seed ◽  
David W. Lazinski ◽  
Andrew Camilli
Keyword(s):  
Host Range ◽  
Vibrio Cholerae ◽  
Receptor Binding ◽  
Mutant Phenotype ◽  
Tail Fiber ◽  
Missense Mutations ◽  
Wild Type ◽  
Mutant Strains ◽  
Stool Samples ◽  
Receptor Binding Protein

ICP2 is a virulent bacteriophage (phage) that preys on Vibrio cholerae. ICP2 was first isolated from cholera patient stool samples. Some of these stools also contained ICP2-resistant isogenic V. cholerae strains harboring missense mutations in the trimeric outer membrane porin protein OmpU, identifying it as the ICP2 receptor. In this study, we identify the ICP2 proteins that mediate interactions with OmpU by selecting for ICP2 host-range mutants within infant rabbits infected with a mixture of wild type and OmpU mutant strains. ICP2 host-range mutants, that can now infect OmpU mutant strains, had missense mutations in putative tail fiber gene gp25 and putative adhesin gp23. Using site-specific mutagenesis we show that single or double mutations in gp25 are sufficient to generate the host-range mutant phenotype. However, at least one additional mutation in gp23 is required for robust plaque formation on specific OmpU mutants. Mutations in gp23 alone were insufficient to give a host-range mutant phenotype. All ICP2 host-range mutants retained the ability to plaque on wild type V. cholerae cells. The strength of binding of host-range mutants to V. cholerae correlated with plaque morphology, indicating that the selected mutations in gp25 and gp23 restore molecular interactions with the receptor. We propose that ICP2 host-range mutants evolve by a two-step process where, first, gp25 mutations are selected for their broad host-range, albeit accompanied by low level phage adsorption. Subsequent selection occurs for gp23 mutations that further increase productive binding to specific OmpU alleles, allowing for near wild type efficiencies of adsorption and subsequent phage multiplication. Importance Concern over multidrug-resistant bacterial pathogens, including Vibrio cholerae, has led to a renewed interest in phage biology and their potential for phage therapy. ICP2 is a genetically unique virulent phage isolated from cholera patient stool samples. It is also one of three phages in a prophylactic cocktail shown to be effective in animal models of infection and the only one of the three that requires a protein receptor (OmpU). This study identifies an ICP2 tail fiber and a receptor binding protein and examines how ICP2 responds to the selective pressures of phage-resistant OmpU mutants. We found that this particular co-evolutionary arms race presents fitness costs to both ICP2 and V. cholerae.

scholarly journals Proteomic Identification ofsaeRS-Dependent Targets Critical for Protective Humoral Immunity against Staphylococcus aureus Skin Infection

2015 ◽  
Vol 83 (9) ◽  
pp. 3712-3721 ◽  
Author(s):  
Fan Zhao ◽  
Brian L. Cheng ◽  
Susan Boyle-Vavra ◽  
Maria-Luisa Alegre ◽  
Robert S. Daum ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Polyclonal Antibody ◽  
Protective Immunity ◽  
Dominant Role ◽  
Recurrent Infection ◽  
Antibody Responses ◽  
Content Type ◽  
Proteomic Approach ◽  
Protective Antibodies ◽  
Antibody Levels

RecurrentStaphylococcus aureusskin and soft tissue infections (SSTIs) are common despite detectable antibody responses, leading to the belief that the immune response elicited by these infections is not protective. We recently reported thatS. aureusUSA300 SSTI elicits antibodies that protect against recurrent SSTI in BALB/c but not C57BL/6 mice, and in this study, we aimed to uncover the specificity of the protective antibodies. Using a proteomic approach, we found thatS. aureusSSTI elicited broad polyclonal antibody responses in both BALB/c and C57BL/6 mice and identified 10S. aureusantigens against which antibody levels were significantly higher in immune BALB/c serum. Four of the 10 antigens identified are regulated by thesaeRSoperon, suggesting a dominant role forsaeRSin protection. Indeed, infection with USA300Δsaefailed to protect against secondary SSTI with USA300, despite eliciting a strong polyclonal antibody response against antigens whose expression is not regulated bysaeRS. Moreover, the antibody repertoire after infection with USA300Δsaelacked antibodies specific for 10saeRS-regulated antigens, suggesting that all or a subset of these antigens are necessary to elicit protective immunity. Infection with USA300Δhlaelicited modest protection against secondary SSTI, and complementation of USA300Δsaewithhlarestored protection but incompletely. Together, these findings support a role for both Hla and othersaeRS-regulated antigens in eliciting protection and suggest that host differences in immune responses tosaeRS-regulated antigens may determine whetherS. aureusinfection elicits protective or nonprotective immunity against recurrent infection.

scholarly journals Spodoptera frugiperda (J. E. Smith) Aminopeptidase N1 Is a Functional Receptor of the Bacillus thuringiensis Cry1Ca Toxin

2018 ◽  
Vol 84 (17) ◽  
Author(s):  
Isabel Gómez ◽  
Daniel E. Rodríguez-Chamorro ◽  
Gabriela Flores-Ramírez ◽  
Ricardo Grande ◽  
Fernando Zúñiga ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Receptor Binding ◽  
Spodoptera Frugiperda ◽  
Binding Proteins ◽  
Membrane Vesicles ◽  
Amino Acid Residues ◽  
Content Type ◽  
Different Populations ◽  
Domain Iii ◽  
Functional Receptor

ABSTRACT Bacillus thuringiensis Cry1Ca is toxic to different Spodoptera species. The aims of this work were to identify the Cry1Ca-binding proteins in S. frugiperda, to provide evidence on their participation in toxicity, and to identify the Cry1Ca amino acid residues involved in receptor binding. Pulldown assays using Spodoptera frugiperda brush border membrane vesicles (BBMV) identified aminopeptidase N (APN), APN1, and APN2 isoforms as Cry1Ca-binding proteins. Cry1Ca alanine substitutions in all residues of domain III β16 were characterized. Two β16 nontoxic mutants (V505A and S506A) showed a correlative defect on binding to the recombinant S. frugiperda APN1 (SfAPN1). Finally, silencing the expression of APN1 transcript, by double-stranded RNA (dsRNA) feeding, showed that silenced larvae are more tolerant of the Cry1Ca toxin, which induced less than 40% mortality in silenced larvae whereas nonsilenced larvae had 100% mortality. Overall, our results show that Cry1Ca relies on APN1 binding through domain III β16 to impart toxicity to S. frugiperda. IMPORTANCE Bacillus thuringiensis Cry toxins rely on receptor binding to exert toxicity. Cry1Ca is toxic to different populations of S. frugiperda, a major corn pest in America. Nevertheless, the S. frugiperda midgut proteins that are involved in Cry1Ca toxicity have not been identified. Here we identified aminopeptidase N1 (APN1) as a functional receptor of Cry1Ca. Moreover, we showed that Cry1Ca domain III β16 is involved in APN1 binding. These results give insights on potential target sites for improving Cry1Ca toxicity to S. frugiperda.

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