1
|
Ferrari ML, Charova SN, Sansonetti PJ, Mylonas E, Gazi AD. Structural Insights of Shigella Translocator IpaB and Its Chaperone IpgC in Solution. Front Cell Infect Microbiol 2021; 11:673122. [PMID: 33996640 PMCID: PMC8117225 DOI: 10.3389/fcimb.2021.673122] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/12/2021] [Indexed: 12/18/2022] Open
Abstract
Bacterial Type III Secretion Systems (T3SSs) are specialized multicomponent nanomachines that mediate the transport of proteins either to extracellular locations or deliver Type III Secretion effectors directly into eukaryotic host cell cytoplasm. Shigella, the causing agent of bacillary dysentery or shigellosis, bears a set of T3SS proteins termed translocators that form a pore in the host cell membrane. IpaB, the major translocator of the system, is a key factor in promoting Shigella pathogenicity. Prior to secretion, IpaB is maintained inside the bacterial cytoplasm in a secretion competent folding state thanks to its cognate chaperone IpgC. IpgC couples T3SS activation to transcription of effector genes through its binding to MxiE, probably after the delivery of IpaB to the secretion export gate. Small Angle X-ray Scattering experiments and modeling reveal that IpgC is found in different oligomeric states in solution, as it forms a stable heterodimer with full-length IpaB in contrast to an aggregation-prone homodimer in the absence of the translocator. These results support a stoichiometry of interaction 1:1 in the IpgC/IpaB complex and the multi-functional nature of IpgC under different T3SS states.
Collapse
Affiliation(s)
- Mariana L. Ferrari
- Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, Paris, France
- INSERM U1202, Paris, France
| | - Spyridoula N. Charova
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas (IMBB-FORTH), Heraklion, Crete, Greece
| | - Philippe J. Sansonetti
- Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, Paris, France
- INSERM U1202, Paris, France
- Collège de France, Paris, France
| | - Efstratios Mylonas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas (IMBB-FORTH), Heraklion, Crete, Greece
| | - Anastasia D. Gazi
- Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, Paris, France
- INSERM U1202, Paris, France
- UtechS Ultrastructural Bio-Imaging (UBI), Institut Pasteur, Paris, France
| |
Collapse
|
2
|
Mo X, Zhang L, Liu Y, Wang X, Bai J, Lu K, Zou S, Dong H, Chen L. Three Proteins (Hpa2, HrpF and XopN) Are Concomitant Type III Translocators in Bacterial Blight Pathogen of Rice. Front Microbiol 2020; 11:1601. [PMID: 32793141 PMCID: PMC7390958 DOI: 10.3389/fmicb.2020.01601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/18/2020] [Indexed: 12/31/2022] Open
Abstract
Type III (T3) proteic effectors occupy most of the virulence determinants in eukaryote-pathogenic Gram-negative bacteria. During infection, bacteria may deploy a nanomachinery called translocon to deliver T3 effectors into host cells, wherein the effectors fulfill their pathological functions. T3 translocon is hypothetically assembled by bacterial translocators, which have been identified as one hydrophilic and two hydrophobic proteins in animal-pathogenic bacteria but remain unclear in plant pathogens. Now we characterize Hpa2, HrpF, and XopN proteins as concomitant T3 translocators in rice bacterial blight pathogen by analyzing pathological consequences of single, double, and triple gene knockout or genetic complementation. Based on these genetic analyses, Hpa2, HrpF, and XopN accordingly contribute to 46.9, 60.3, and 69.8% proportions of bacterial virulence on a susceptible rice variety. Virulence performances of Hpa2, HrpF, and XopN were attributed to their functions in essentially mediating from-bacteria-into-rice-cell translocation of PthXo1, the bacterial T3 effector characteristic of transcription factors targeting plant genes. On average, 61, 62, and 71% of PthXo1 translocation are provided correspondingly by Hpa2, HrpF, and XopN, while they cooperate to support PthXo1 translocation at a greater-than-95% extent. As a result, rice disease-susceptibility gene SWEET11, which is the regulatory target of PthXo1, is activated to confer bacterial virulence and induce the leaf blight disease in rice. Furthermore, the three translocators also undergo translocation, but only XopN is highly translocated to suppress rice defense responses, suggesting that different components of a T3 translocon deploy distinct virulence mechanisms in addition to the common function in mediating bacterial effector translocation.
Collapse
Affiliation(s)
- Xuyan Mo
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Liyuan Zhang
- College of Plant Protection, Shandong Agricultural University, Tai’an, China
- Crop Molecular Biology Research Group, State Key Laboratory of Crop Biology, Tai’an, China
| | - Yan Liu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Xuan Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Jiaqi Bai
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Kai Lu
- College of Plant Protection, Shandong Agricultural University, Tai’an, China
| | - Shenshen Zou
- College of Plant Protection, Shandong Agricultural University, Tai’an, China
- Crop Molecular Biology Research Group, State Key Laboratory of Crop Biology, Tai’an, China
| | - Hansong Dong
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- College of Plant Protection, Shandong Agricultural University, Tai’an, China
- Crop Molecular Biology Research Group, State Key Laboratory of Crop Biology, Tai’an, China
| | - Lei Chen
- College of Plant Protection, Shandong Agricultural University, Tai’an, China
- Crop Molecular Biology Research Group, State Key Laboratory of Crop Biology, Tai’an, China
| |
Collapse
|