Cotesia plutellae Bracovirus Suppresses Expression of an Antimicrobial Peptide, Cecropin, in the Diamondback Moth, Plutella xylostella, Challenged by Bacteria

Barandoc, Karen P.,Kim, Jae-Hyun,Kim, Yong-Gyun 한국미생물학회 2010 The journal of microbiology Vol.48 No.1

An endoparasitoid wasp, Cotesia plutellae, induces significant immunosuppression of host insect, Plutella xylostella. This study was focused on suppression in humoral immune response of P. xylostella parasitized by C. plutellae. An EST database of P. xylostella provided a putative cecropin gene (PxCec) which is 627 bp long and encodes 66 amino acids. A signal peptide (22 amino acids) is predicted and two putative O-glycosylation sites in threonine are located at positions 58 and 64. Without bacterial infection, PxCec was expressed in pupa and adult stages but not in the egg and larval stages. Upon bacterial challenge, however, the larvae expressed PxCec as early as 3 h post infection (PI) and maintained high expression levels at 12-24 h PI. By 48 h PI, its expression noticeably diminished. All tested tissues of bacteria-infected P. xylostella showed PxCec expression. However, other microbes, such as virus and fungus, did not induce the PxCec expression. Parasitization by C. plutellae suppressed the expression of PxCec in response to bacterial challenge. Among the parasitic factors of C. plutellae, its symbiotic virus (C. plutellae bracovirus: CpBV) alone was able to inhibit the expression of PxCec of P. xylostella challenged by bacteria. These results indicate that PxCec expression is regulated by both immune and developmental processes in P. xylostella. The parasitization by C. plutellae inhibited the expression of PxCec by the wasp's symbiotic virus.

A Cysteine- rich Protein Encoded in Cotesia plutellae Bracovirus Genome is an Immunosuppressant

Karen P. Barandoc,Yonggyun Kim 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.05

A cysteine- rich protein encoded by Cotesia plutellae bacovirus (CpBV) was identified in the parasitized Plutella xylostella. The gene, called CpBV-CRP, encodes 189 amino acids with a signal peptide of 20 residues at N-terminus determined by bioinformatic analysis, suggesting a secretory protein. High CpBV-CRP expression in the parasitized P. xylostella was observed at early days after parasitization and decreased with the course of parasitization. Expression of CpBV-CRP was tissue-specific in the fat body/epidermis, but not in hemocyte and gut. Its physiological function was analyzed by transient expression of a CpBV segment containing CpBV-CRP. The treated larvae underwent an immunosuppression in terms of hemocyte-spreading behavior. When the treated larvae were also co-injected with dsRNA against CpBV-CRP, the suppressed hemocyte behavior was significantly recovered. This study reports a cysteine-rich protein encoded in CpBV genome and its physiological function to be an immunosuppressant.

A SERI technique reveals an immunosuppressive activity of a serine-rich protein encoded in Cotesia plutellae bracovirus

( Karen P. Barandoc ),( Jay Young Park ),( Yong Gyun Kim ) 한국생화학분자생물학회 (구 한국생화학회) 2010 BMB Reports Vol.43 No.4

Polydnavirus genome is segmented and dispersed on host wasp chromosome. After replication, the segments form double-stranded circular DNAs and embedded in viral coat proteins. These viral particles are delivered into a parasitized host along with parasitoid eggs. A serine-rich protein (SRP) is predicted in a polydnavirus, Cotesia plutellae bracovirus (CpBV), genome in its segment no. 33 (CpBV-S33), creating CpBV- SRP1. This study explored its expression and physiological function in the diamondback moth, Plutella xylostella, larvae parasitized by C. plutellae. CpBV-SRP1 encodes 122 amino acids with 26 serines and several predicted phosphorylation sites. It is persistently expressed in all tested tissues of parasitized P. xylostella including hemocyte, fat body, and gut. Its physiological function was analyzed by injecting CpBV-S33 and inducing its expression in nonparasitized P. xylostella by a technique called SERI (segment expression and RNA interference). The expression of CpBV-SRP1 significantly impaired the spreading behavior and total cell count of hemocytes of treated larvae. Subsequent RNA interference of CpBV-SRP1 rescued the immunosuppressive response. This study reports the persistent expression of CpBV-SRP1 in a parasitized host and its parasitic role in suppressing the host immune response by altering hemocyte behavior and survival. [BMB reports 2010; 43(4): 279-283]

Proteomic analysis of Cotesia-associated Host Translation Inhibitory Factors

Karen P. Barandoc,Yonggyun Kim 한국응용곤충학회 2009 한국응용곤충학회 학술대회논문집 Vol.2009 No.05

Upon oviposition, parasitoid wasps inject their eggs along with venom, teratocytes and polydnavirus (PDV) on the host. Among these parasitic factors, PDVs are known to suppress the host immune system and utilize the host translational mechanisms allowing the juvenile parasitoid to develop. Polydnavirusencoded genes can selectively inhibit host translation and still use the translation machinery of the host to synthesize their own proteins. In this study, we utilize a proteomic approach involving two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) that couples isoelectric focusing (IEF) and SDS-PAGE to resolve complex protein mixtures that results from the parastization of Cotesia plutellae on the lepidopteran host, Plutella xylostella. We specifically analyze the changes in protein synthesis using this technique after treatment of HTIFs that has been previously identified on C. plutellae. The difference in protein profile due to parasitization was confirmed by in vitro translation assay using rabbit reticulosyte lysate.

Characterization of the Interaction of Sulfiredoxin (Srx1) with a Vacoular Protein α-Mannosidase (Ams1) in Saccharomyces cerevisiae

Karen P. Barandoc,Kim, Il-Han 배재대학교 자연과학연구소 2006 自然科學論文集 Vol.17 No.1

산화-환원 활성 단백질중에 하나인 설피레독신과의 결합 단배질을 효모 Two-hybrid 기법을 이용하여 탐색한 결과, 알파-만노시다제가 설피레독신과 특이적으로 결합함을 밝혔다. 알파-만노시다제는 D-만노스 당을 비환원성 말단으로부터 유리시키는 가수분해 효소로서, 세포 원형질에 다량체 형태로 존재한다. 본 연구에서는 설피레독신과 알파-만노시다제간의 단백질결합을 설피레독신의 새로운 생리기능 관점에서 토의했다. Most redox-active proteins have thiol-bearing cysteine residues that are sensitive to oxidation. Cysteine thiols oxidized to sulfenic acid are generally unstable, either forming a disulfide with a nearby thiol or being further oxidized to a stable sulfinic acid, which have been viewed as an irreversible protein modification. However, recent studies showed that cysteine residues of certain thiol peroxidases (Prxs) undergo reversible oxidation to sulfinic acid and the reduction reaction is catalyzed by sulfiredoxin (Srx1). Specific Cys residues of various other proteins are also oxidized to sulfinic acid (Cys-SO_(2)H). Srx1 is considered one of the oxidant proteins with a role in signaling through catalytic reduction of oxidative modification like in the reduction of glutathionylation, a post-translational, oxidative modification that occurs on numerous proteins. In this study, the role of sulfiredoxin in cellular processes, was investigated by studying its interaction with other proteins. Through the yeast two-hybrid system (Y2HS) technique, we have found that Ams1 is a potential and novel interacting protein partner of Srx1. α-mannosidase (Ams1) is a resident vacuolar hydrolase which aids in recycling macromolecular components of the cell through hydrolysis of terminal, non-reducing α-D-mannose residues. It forms an oligomer in the cytoplasm and under nutrient rich condition and is delivered to the vacuole by the Cytoplasm to Vacuole (Cvt) pathway. Aside from the role of Srx1 as a catalyst in the reduction of cysteine sulfenic acid groups, it may play a completely new function in the cellular process as indicated by its interaction with Ams1 of the yeast Saccharomyces cerevisiae.