Glycoprotein complexes,a kind of structural biomolecules,are characterized by extensive functions,such as immunomodulatory and anti-inflammatory activities.Glycosylation of protein has an important impact on conformat...Glycoprotein complexes,a kind of structural biomolecules,are characterized by extensive functions,such as immunomodulatory and anti-inflammatory activities.Glycosylation of protein has an important impact on conformational stability and active function of glycoprotein complex.Clarifying the structure of glycoprotein complex is the basis for further exploring its biological activities,and the release of sugar chains is one of the key points in the analysis of glycoprotein structures.Glycoprotein complex can affect the expression of immune-related proteins and factors by activating cell surface receptors,regulating intracellular immune signal transduction,and ultimately play an immunomodulatory role in the body.Meanwhile,the chemical structure and advanced structure of glycoprotein complex can significantly affect the immunomodulatory activity.this review focuses on chemical and advanced structural information of glycoprotein,the regulation mechanism of immunomodulation and the structure-activity relationship,which aims to provide a theoretical basis for the basic research on the immunomodulatory activity of food-derived glycoproteins and the development of related functional products.展开更多
Mammarenaviruses, including lethal pathogens such as Lassa virus and Junin virus, can cause severe hemorrhagic fever in humans. Entry is a key step for virus infection, which starts with binding of the envelope glycop...Mammarenaviruses, including lethal pathogens such as Lassa virus and Junin virus, can cause severe hemorrhagic fever in humans. Entry is a key step for virus infection, which starts with binding of the envelope glycoprotein （GP） to receptors on target cells and subsequent fusion of the virus with target cell membranes. The GP precursor is synthesized as a polypeptide, and maturation occurs by two cleavage events, yielding a tripartite GP complex （GPC） formed by a stable signal peptide （SSP）, GP1 and GP2. The unique retained SSP interacts with GP2 and plays essential roles in virion maturation and infectivity. GP1 is responsible for binding to the cell receptor, and GP2 is a class I fusion protein. The native structure of the tripartite GPC is unknown. GPC is critical for the receptor binding, membrane fusion and neutralization antibody recognition. Elucidating the molecular mechanisms underlining the structure-function relationship of the three subunits is the key for understanding their function and can facilitate novel avenues for combating virus infections. This review summarizes the basic aspects and recent research of the structure-function relationship of the three subunits. We discuss the structural basis of the receptor-binding domain in GP1, the interaction between SSP and GP2 and its role in virion maturation and membrane fusion, as well as the mechanism by which glycosylation stabilizes the GPC structure and facilitates immune evasion. Understanding the molecular mechanisms involved in these aspects will contribute to the development of novel vaccines and treatment strategies against mammarenaviruses infection.展开更多
The membrane-proximal external region(MPER)of Lassa virus(LASV)glycoprotein complex(GPC)is critical in modulating its functionality.Till now,the high-resolution structure of the intact GPC,including MPER is not availa...The membrane-proximal external region(MPER)of Lassa virus(LASV)glycoprotein complex(GPC)is critical in modulating its functionality.Till now,the high-resolution structure of the intact GPC,including MPER is not available.In this study,we used alanine substitution to scan all 16 residues located in LASV MPER.Western blotting and quantification fusion assay showed that the residues located at the C terminus of the HR2(M414 and L415)and N terminus of the MPER(K417 and Y419)are critical for GPC-mediated membrane fusion function.Furthermore,cell surface biotinylation experiments revealed that M414 A,K417 A and Y419 A expressed similar levels as WT,whereas L415 A mutant led to a reduction of mature GPC on the cell surface.Moreover,substitution of these residues with the similar residue such as M414 L,L415 I,K417 R and Y419 F would partly compensate the loss of the fusion activity caused by the alanine mutant in these sites.Results from this study showed that several key residues in the MPER region are indispensable to promote the conformational changes that drive fusion events and shed light on the structure analysis of LASV GPC and anti-LASV therapeutics.展开更多
Human cytomegalovirus virions contain three major glycoprotein complexes (gC I, II, III), all of which are required for CMV infectivity. These complexes also represent major antigenic targets for anti-viral immune res...Human cytomegalovirus virions contain three major glycoprotein complexes (gC I, II, III), all of which are required for CMV infectivity. These complexes also represent major antigenic targets for anti-viral immune responses. The gC II complex consists of two glycoproteins, gM and gN. In the current study, DNA vaccines expressing the murine cytomegalovirus (MCMV) homologs of the gM and gN proteins were evaluated for protection against lethal MCMV infection in a mouse model. Humoral and cellular immune responses, spleen viral titers, and mice survival and body-weight changes were examined. The results showed that immunization with gM or gN DNA vaccine alone was not able to offer good protection, whereas co-immunization with both gM and gN induced an effective neutralizing antibody response and cellular immune response, and provided mice with complete protection against a lethal MCMV challenge. This study provides the first in vivo evidence that the gC II (gM-gN) complex may be able to serve as a protective subunit antigen for future HCMV vaccine development.展开更多
Lassa virus(LASV)belongs to the Mammarenavirus genus(family Arenaviridae)and causes severe hemorrhagic fever in humans.The glycoprotein complex(GPC)contains eleven N-linked glycans that play essential roles in GPC fun...Lassa virus(LASV)belongs to the Mammarenavirus genus(family Arenaviridae)and causes severe hemorrhagic fever in humans.The glycoprotein complex(GPC)contains eleven N-linked glycans that play essential roles in GPC functionalities such as cleavage,transport,receptor recognition,epitope shielding,and immune response.We used three mutagenesis strategies(asparagine to glutamine,asparagine to alanine,and serine/tyrosine to alanine mutants)to abolish individual glycan chain on GPC and found that all the three strategies led to cleavage inefficiency on the 2nd(N89),5th(N119),or 8th(N365)glycosylation motif.To evaluate N to Q mutagenesis for further research,it was found that deletion of the 2nd(N89Q)or 8th(N365Q)glycan completely inhibited the transduction efficiency of pseudotyped particles.We further investigated the role of individual glycan on GPC-mediated immune response by DNA immunization of mice.Deletion of the individual 1st(N79Q),3rd(N99Q),5th(N119Q),or 6th(N167Q)glycan significantly enhanced the proportion of effector CD4+cells,whereas deletion of the 1st(N79Q),2nd(N89Q),3rd(N99Q),4th(N109Q),5th(N119Q),6th(N167Q),or 9th(N373Q)glycan enhanced the proportion of CD8+effector T cells.Deletion of specific glycan improves the Th1-type immune response,and abolishment of glycan on GPC generally increases the antibody titer to the glycan-deficient GPC.However,the antibodies from either the mutant or WT GPC-immunized mice show little neutralization effect on wild-type LASV.The glycan residues on GPC provide an immune shield for the virus,and thus represent a target for the design and development of a vaccine.展开更多
The Lassa virus(LASV)is endemic in West Africa and causes severe hemorrhagic Lassa fever in humans.The glycoprotein complex(GPC)of LASV is highly glycosylation-modified,with 11 N-glycosylation sites.All 11 N-linked gl...The Lassa virus(LASV)is endemic in West Africa and causes severe hemorrhagic Lassa fever in humans.The glycoprotein complex(GPC)of LASV is highly glycosylation-modified,with 11 N-glycosylation sites.All 11 N-linked glycan chains play critical roles in GPC cleavage,folding,receptor binding,membrane fusion,and immune evasion.In this study,we focused on the first glycosylation site because its deletion mutant(N79Q)results in an unexpected enhanced membrane fusion,whereas it exerts little effect on GPC expression,cleavage,and receptor binding.Meanwhile,the pseudotype virus bearing GPC_(N79Q)was more sensitive to the neutralizing antibody 37.7H and was attenuated in virulence.Exploring the biological functions of the key glycosylation site on LASV GPC will help elucidate the mechanism of LASV infection and provide strategies for the development of attenuated vaccines against LASV infection.展开更多
基金supported by Yunnan fundamental Research Projects(202301as070014)Yunnan Department of science and technology innovation Guidance and technology Enterprise Cultivation Plan(202204BP090031).
文摘Glycoprotein complexes,a kind of structural biomolecules,are characterized by extensive functions,such as immunomodulatory and anti-inflammatory activities.Glycosylation of protein has an important impact on conformational stability and active function of glycoprotein complex.Clarifying the structure of glycoprotein complex is the basis for further exploring its biological activities,and the release of sugar chains is one of the key points in the analysis of glycoprotein structures.Glycoprotein complex can affect the expression of immune-related proteins and factors by activating cell surface receptors,regulating intracellular immune signal transduction,and ultimately play an immunomodulatory role in the body.Meanwhile,the chemical structure and advanced structure of glycoprotein complex can significantly affect the immunomodulatory activity.this review focuses on chemical and advanced structural information of glycoprotein,the regulation mechanism of immunomodulation and the structure-activity relationship,which aims to provide a theoretical basis for the basic research on the immunomodulatory activity of food-derived glycoproteins and the development of related functional products.
文摘Mammarenaviruses, including lethal pathogens such as Lassa virus and Junin virus, can cause severe hemorrhagic fever in humans. Entry is a key step for virus infection, which starts with binding of the envelope glycoprotein （GP） to receptors on target cells and subsequent fusion of the virus with target cell membranes. The GP precursor is synthesized as a polypeptide, and maturation occurs by two cleavage events, yielding a tripartite GP complex （GPC） formed by a stable signal peptide （SSP）, GP1 and GP2. The unique retained SSP interacts with GP2 and plays essential roles in virion maturation and infectivity. GP1 is responsible for binding to the cell receptor, and GP2 is a class I fusion protein. The native structure of the tripartite GPC is unknown. GPC is critical for the receptor binding, membrane fusion and neutralization antibody recognition. Elucidating the molecular mechanisms underlining the structure-function relationship of the three subunits is the key for understanding their function and can facilitate novel avenues for combating virus infections. This review summarizes the basic aspects and recent research of the structure-function relationship of the three subunits. We discuss the structural basis of the receptor-binding domain in GP1, the interaction between SSP and GP2 and its role in virion maturation and membrane fusion, as well as the mechanism by which glycosylation stabilizes the GPC structure and facilitates immune evasion. Understanding the molecular mechanisms involved in these aspects will contribute to the development of novel vaccines and treatment strategies against mammarenaviruses infection.
基金the National Key Research and Development Program of China (2018YFA0507204)the National Natural Sciences Foundation of China (31670165)+1 种基金Wuhan National Biosafety Laboratory,Chinese Academy of Sciences Advanced Customer Cultivation Project (2019ACCP-MS03)the Open Research Fund Program of the State Key Laboratory of Virology of China (2018IOV001)。
文摘The membrane-proximal external region(MPER)of Lassa virus(LASV)glycoprotein complex(GPC)is critical in modulating its functionality.Till now,the high-resolution structure of the intact GPC,including MPER is not available.In this study,we used alanine substitution to scan all 16 residues located in LASV MPER.Western blotting and quantification fusion assay showed that the residues located at the C terminus of the HR2(M414 and L415)and N terminus of the MPER(K417 and Y419)are critical for GPC-mediated membrane fusion function.Furthermore,cell surface biotinylation experiments revealed that M414 A,K417 A and Y419 A expressed similar levels as WT,whereas L415 A mutant led to a reduction of mature GPC on the cell surface.Moreover,substitution of these residues with the similar residue such as M414 L,L415 I,K417 R and Y419 F would partly compensate the loss of the fusion activity caused by the alanine mutant in these sites.Results from this study showed that several key residues in the MPER region are indispensable to promote the conformational changes that drive fusion events and shed light on the structure analysis of LASV GPC and anti-LASV therapeutics.
基金supported by the Innovation Platform Open Fund of Hunan Provincial Education Department (11K010)a research fund from Hunan Provincial Science and Technology Development (2008TP4033-2)
文摘Human cytomegalovirus virions contain three major glycoprotein complexes (gC I, II, III), all of which are required for CMV infectivity. These complexes also represent major antigenic targets for anti-viral immune responses. The gC II complex consists of two glycoproteins, gM and gN. In the current study, DNA vaccines expressing the murine cytomegalovirus (MCMV) homologs of the gM and gN proteins were evaluated for protection against lethal MCMV infection in a mouse model. Humoral and cellular immune responses, spleen viral titers, and mice survival and body-weight changes were examined. The results showed that immunization with gM or gN DNA vaccine alone was not able to offer good protection, whereas co-immunization with both gM and gN induced an effective neutralizing antibody response and cellular immune response, and provided mice with complete protection against a lethal MCMV challenge. This study provides the first in vivo evidence that the gC II (gM-gN) complex may be able to serve as a protective subunit antigen for future HCMV vaccine development.
基金This work was supported by the National Key Research and Development Program of China(2018YFA0507204)the National Natural Sciences Foundation of China(31670165)+1 种基金Wuhan National Biosafety Laboratory,Chinese Academy of Sciences Advanced Customer Cultivation Project(2019ACCP-MS03)the Open Research Fund Program of the State Key Laboratory of Virology of China(2018IOV001).Author Contributions。
文摘Lassa virus(LASV)belongs to the Mammarenavirus genus(family Arenaviridae)and causes severe hemorrhagic fever in humans.The glycoprotein complex(GPC)contains eleven N-linked glycans that play essential roles in GPC functionalities such as cleavage,transport,receptor recognition,epitope shielding,and immune response.We used three mutagenesis strategies(asparagine to glutamine,asparagine to alanine,and serine/tyrosine to alanine mutants)to abolish individual glycan chain on GPC and found that all the three strategies led to cleavage inefficiency on the 2nd(N89),5th(N119),or 8th(N365)glycosylation motif.To evaluate N to Q mutagenesis for further research,it was found that deletion of the 2nd(N89Q)or 8th(N365Q)glycan completely inhibited the transduction efficiency of pseudotyped particles.We further investigated the role of individual glycan on GPC-mediated immune response by DNA immunization of mice.Deletion of the individual 1st(N79Q),3rd(N99Q),5th(N119Q),or 6th(N167Q)glycan significantly enhanced the proportion of effector CD4+cells,whereas deletion of the 1st(N79Q),2nd(N89Q),3rd(N99Q),4th(N109Q),5th(N119Q),6th(N167Q),or 9th(N373Q)glycan enhanced the proportion of CD8+effector T cells.Deletion of specific glycan improves the Th1-type immune response,and abolishment of glycan on GPC generally increases the antibody titer to the glycan-deficient GPC.However,the antibodies from either the mutant or WT GPC-immunized mice show little neutralization effect on wild-type LASV.The glycan residues on GPC provide an immune shield for the virus,and thus represent a target for the design and development of a vaccine.
基金the National Key Research and Development Program(2022YFC2303300,2018YFA0507204)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0490000)the Na-tional Natural Science Foundation of China(82172273,31670165).
文摘The Lassa virus(LASV)is endemic in West Africa and causes severe hemorrhagic Lassa fever in humans.The glycoprotein complex(GPC)of LASV is highly glycosylation-modified,with 11 N-glycosylation sites.All 11 N-linked glycan chains play critical roles in GPC cleavage,folding,receptor binding,membrane fusion,and immune evasion.In this study,we focused on the first glycosylation site because its deletion mutant(N79Q)results in an unexpected enhanced membrane fusion,whereas it exerts little effect on GPC expression,cleavage,and receptor binding.Meanwhile,the pseudotype virus bearing GPC_(N79Q)was more sensitive to the neutralizing antibody 37.7H and was attenuated in virulence.Exploring the biological functions of the key glycosylation site on LASV GPC will help elucidate the mechanism of LASV infection and provide strategies for the development of attenuated vaccines against LASV infection.
