title: Crystal structural basis for Rv0315, an immunostimulatory antigen and inactive beta-1,3-glucanase of Mycobacterium tuberculosis.
abstract: Mycobacterium tuberculosis (Mtb) remains a leading cause of morbidity and mortality worldwide, as two billion people are latently infected with Mtb. To address Mtb drug resistance and the limitations of current vaccines, the characteristics of candidate Mtb vaccines need to be explored. Here, we report the three-dimensional structure of Rv0315 at 1.70 Å resolution, a novel immunostimulatory antigen of Mtb, and demonstrate that Rv0315 is an inactive β-1,3-glucanase of the glycoside hydrolase 16 (GH16) family. Our study further elaborates the molecular basis for the lack of glucan recognition by Rv0315. Rv0315 has a large open groove, and this particular topology cannot bind oligosaccharide chains in solution, thus explaining the lack of detectable hydrolytic activity towards its substrate. Additionally, we identified Glu-176, a conserved catalytic residue in GH16 endo-β-1,3-glucanases, as essential for Rv0315 to induce immunological responses. These results indicate that Rv0315 likely diverged from a broad-specificity ancestral GH16 glucanase, and this inactive member of the GH16 family offers new insights into the GH16 glucanase. Together, our findings suggest that an inactive β-1,3-glucanase in Mtb drives T-helper 1 (Th1) immune responses, which may help develop more effective vaccines against Mtb infection.
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Wanyu
authors.initials: W
authors.lastname: Dong
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Junhua
authors.initials: J
authors.lastname: Huang
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Li
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Yubei
authors.initials: Y
authors.lastname: Tan
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Shen
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Song
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Dang
authors.initials: D
authors.lastname: Wang
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Shaobo
authors.initials: S
authors.lastname: Xiao
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Huanchun
authors.initials: H
authors.lastname: Chen
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.|Departments of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
authors.forename: Zhen F
authors.initials: ZF
authors.lastname: Fu
authors.affiliation: The National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, China.|College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Guiqing
authors.initials: G
authors.lastname: Peng
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000276:immunology; D018360:Crystallography, X-Ray; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology; D043326:Glucan 1,3-beta-Glucosidase / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D005936:Glucans / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology*; D016328:NF-kappa B / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D016415:Sequence Alignment; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D005936:Glucans; D016328:NF-kappa B; C008247:laminaran; D043326:Glucan 1,3-beta-Glucosidase