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Xu J, Ma S, Huang Y, Zhang Q, Huang L, Xu H, Suleiman IM, Li P, Wang Z, Xie J. Mycobacterium marinum MMAR_0267-regulated copper utilization facilitates bacterial escape from phagolysosome. Commun Biol 2024; 7:1180. [PMID: 39300168 DOI: 10.1038/s42003-024-06860-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 09/06/2024] [Indexed: 09/22/2024] Open
Abstract
The host limits Mycobacterium tuberculosis (Mtb) by enriching copper in high concentrations. This research investigates how Mtb escapes copper stress. The membrane protein encoded by Mtb Rv0102, when its homolog in M. smegmatis (MSMEG_4702) was knocked out, resulted in a fourfold decrease in intracellular copper levels and enhanced tolerance to elevated extracellular copper concentrations. Similarly, knockout mutants of its homolog in M. marinum (MMAR_0267) showed increased virulence in zebrafish and higher bacterial load within macrophages. In THP-1 cells infected with MMAR_0267 deletion mutants, the intracellular survival of these mutants increased, along with reduced THP-1 cell apoptosis. Deficiency in copper down-regulated the transcriptional level of the virulence factor CFP-10 in M. marinum, suppressed cytosolic signaling via the macrophage STING pathway, leading to decreased production of IFN-β and reduced cell apoptosis. In conclusion, these findings highlight the significant impact of copper on the survival and reproduction of mycobacteria, underscoring the importance of studying mycobacterial adaptation mechanisms in copper-rich environments.
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Affiliation(s)
- Junqi Xu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Key Laboratory of Aquatic Science of Chongqing, Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China
| | - Shaying Ma
- Chongqing Public Health Medical Center, Chongqing, China
| | - Yu Huang
- Chongqing Emergency Medical Center, Chongqing the Fourth Hospital, Jiankang Road, Yuzhong, Chongqing, 400014, China
| | - Qiao Zhang
- Chongqing Emergency Medical Center, Chongqing the Fourth Hospital, Jiankang Road, Yuzhong, Chongqing, 400014, China
| | - Lingxi Huang
- Chongqing Emergency Medical Center, Chongqing the Fourth Hospital, Jiankang Road, Yuzhong, Chongqing, 400014, China
| | - Hongxiang Xu
- Chongqing Emergency Medical Center, Chongqing the Fourth Hospital, Jiankang Road, Yuzhong, Chongqing, 400014, China
| | - Ismail Mohamed Suleiman
- Chongqing Emergency Medical Center, Chongqing the Fourth Hospital, Jiankang Road, Yuzhong, Chongqing, 400014, China
| | - Peibo Li
- Chongqing Public Health Medical Center, Chongqing, China.
| | - Zhijian Wang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Key Laboratory of Aquatic Science of Chongqing, Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China.
| | - Jianping Xie
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Key Laboratory of Aquatic Science of Chongqing, Institute of Modern Biopharmaceuticals, School of Life Sciences, Southwest University, Chongqing, 400715, China.
- Chongqing Public Health Medical Center, Chongqing, China.
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Höhler M, Alcázar-Román AR, Schenk K, Aguirre-Huamani MP, Braun C, Zrieq R, Mölleken K, Hegemann JH, Fleig U. Direct targeting of host microtubule and actin cytoskeletons by a chlamydial pathogenic effector protein. J Cell Sci 2024; 137:jcs263450. [PMID: 39099397 PMCID: PMC11444262 DOI: 10.1242/jcs.263450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Accepted: 07/25/2024] [Indexed: 08/06/2024] Open
Abstract
To propagate within a eukaryotic cell, pathogenic bacteria hijack and remodulate host cell functions. The Gram-negative obligate intracellular Chlamydiaceae, which pose a serious threat to human and animal health, attach to host cells and inject effector proteins that reprogram host cell machineries. Members of the conserved chlamydial TarP family have been characterized as major early effectors that bind to and remodel the host actin cytoskeleton. We now describe a new function for the Chlamydia pneumoniae TarP member CPn0572, namely the ability to bind and alter the microtubule cytoskeleton. Thus, CPn0572 is unique in being the only prokaryotic protein that directly modulates both dynamic cytoskeletons of a eukaryotic cell. Ectopically expressed GFP-CPn0572 associates in a dose-independent manner with either cytoskeleton singly or simultaneously. In vitro, CPn0572 binds directly to microtubules. Expression of a microtubule-only CPn0572 variant resulted in the formation of an aberrantly thick, stabilized microtubule network. Intriguingly, during infection, secreted CPn0572 also colocalized with altered microtubules, suggesting that this protein also affects microtubule dynamics during infection. Our analysis points to a crosstalk between actin and microtubule cytoskeletons via chlamydial CPn0572.
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Affiliation(s)
- Mona Höhler
- Eukaryotic Microbiology, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | | | - Katharina Schenk
- Eukaryotic Microbiology, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | | | - Corinna Braun
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Rafat Zrieq
- Department of Public Health, College of Public Health and Health Informatics, University of Ha'il, Ha'il City 2440, Saudi Arabia
- Applied Science Research Centre, Applied Science Private University, Amman 11931, Jordan
| | - Katja Mölleken
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Johannes H Hegemann
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Ursula Fleig
- Eukaryotic Microbiology, Heinrich-Heine-University, 40225 Düsseldorf, Germany
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3
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Kocher F, Applegate V, Reiners J, Port A, Spona D, Hänsch S, Mirzaiebadizi A, Ahmadian MR, Smits SHJ, Hegemann JH, Mölleken K. The Chlamydia pneumoniae effector SemD exploits its host's endocytic machinery by structural and functional mimicry. Nat Commun 2024; 15:7294. [PMID: 39181890 PMCID: PMC11344771 DOI: 10.1038/s41467-024-51681-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 08/15/2024] [Indexed: 08/27/2024] Open
Abstract
To enter epithelial cells, the obligate intracellular pathogen Chlamydia pneumoniae secretes early effector proteins, which bind to and modulate the host-cell's plasma membrane and recruit several pivotal endocytic host proteins. Here, we present the high-resolution structure of an entry-related chlamydial effector protein, SemD. Co-crystallisation of SemD with its host binding partners demonstrates that SemD co-opts the Cdc42 binding site to activate the actin cytoskeleton regulator N-WASP, making active, GTP-bound Cdc42 superfluous. While SemD binds N-WASP much more strongly than Cdc42 does, it does not bind the Cdc42 effector protein FMNL2, indicating effector protein specificity. Furthermore, by identifying flexible and structured domains, we show that SemD can simultaneously interact with the membrane, the endocytic protein SNX9, and N-WASP. Here, we show at the structural level how a single effector protein can hijack central components of the host's endocytic system for efficient internalization.
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Affiliation(s)
- Fabienne Kocher
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute for Functional Microbial Genomics, Düsseldorf, Germany
| | - Violetta Applegate
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Center for Structural Studies, Düsseldorf, Germany
| | - Jens Reiners
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Center for Structural Studies, Düsseldorf, Germany
| | - Astrid Port
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Center for Structural Studies, Düsseldorf, Germany
| | - Dominik Spona
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute for Functional Microbial Genomics, Düsseldorf, Germany
| | - Sebastian Hänsch
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Center for Advanced Imaging, Düsseldorf, Germany
| | - Amin Mirzaiebadizi
- Institute of Biochemistry and Molecular Biology II, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Mohammad Reza Ahmadian
- Institute of Biochemistry and Molecular Biology II, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander H J Smits
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Center for Structural Studies, Düsseldorf, Germany
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Biochemistry, Düsseldorf, Germany
| | - Johannes H Hegemann
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute for Functional Microbial Genomics, Düsseldorf, Germany.
| | - Katja Mölleken
- Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute for Functional Microbial Genomics, Düsseldorf, Germany
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Wen Y, Du Y, Shi X, Zeng Z. Clinical diagnosis and treatment of seven patients diagnosed pneumonia caused by Chlamydia abortus: a case series report. Front Med (Lausanne) 2024; 11:1406737. [PMID: 38919935 PMCID: PMC11196609 DOI: 10.3389/fmed.2024.1406737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 05/27/2024] [Indexed: 06/27/2024] Open
Abstract
Background Chlamydia abortus pneumonia is very rare in normal people. At present, there is a lack of clinical data on the clinical characteristics and diagnosis and treatment experience of patients with this type of infection. Our team had recently treated 7 cases of these patients. This study aims to comprehensively summarize and analyze the clinical characteristics and treatment methods of Chlamydia abortus pneumonia, and to provide clinical evidence for the diagnosis and treatment of Chlamydia abortus pneumonia. Methods Clinical data were retrospectively collected from patients diagnosed with Chlamydia abortus pneumonia through metagenomic next-generation sequencing (mNGS) at the Department of Pulmonary and Critical Care Medicine, Meizhou People's Hospital. Results Seven patients with Chlamydia abortus pneumonia reported a history of poultry exposure, experiencing fever alongside respiratory or digestive symptoms. Marked elevation of blood inflammation markers, accompanied by hypoproteinemia and liver damage, was observed. Chest CT scans revealed pneumonia and pleural effusion. Chlamydia abortus was detected in blood or bronchoalveolar lavage fluid (BALF) through mNGS, often co-occurring with Chlamydia psittaci or other bacteria infections. Notably, Doxycycline demonstrated efficacy in treating Chlamydia abortus. Conclusion Chlamydia abortus infection is a zoonotic disease, particularly among individuals with a history of poultry exposure, and mNGS emerges as a reliable diagnostic tool for its detection. Chlamydia abortus infection manifests with systemic and lung inflammation, effectively addressed through Doxycycline therapy.
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Affiliation(s)
- Ya Wen
- Department of Pulmonary and Critical Care Medicine, Meizhou People's Hospital, Meizhou, Guangdong, China
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Nakao H, Nagao M, Yamada T, Imamura K, Nozaki K, Ikeda K, Nakano M. Impact of transmembrane peptides on individual lipid motions and collective dynamics of lipid bilayers. Colloids Surf B Biointerfaces 2023; 228:113396. [PMID: 37311269 DOI: 10.1016/j.colsurfb.2023.113396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/15/2023] [Accepted: 06/05/2023] [Indexed: 06/15/2023]
Abstract
The fluid nature of lipid bilayers is indispensable for the dynamic regulation of protein function and membrane morphology in biological membranes. Membrane-spanning domains of proteins interact with surrounding lipids and alter the physical properties of lipid bilayers. However, there is no comprehensive view of the effects of transmembrane proteins on the membrane's physical properties. Here, we investigated the effects of transmembrane peptides with different flip-flop-promoting abilities on the dynamics of a lipid bilayer employing complemental fluorescence and neutron scattering techniques. The quasi-elastic neutron scattering and fluorescence experiments revealed that lateral diffusion of the lipid molecules and the acyl chain motions were inhibited by the inclusion of transmembrane peptides. The neutron spin-echo spectroscopy measurements indicated that the lipid bilayer became more rigid but more compressible and the membrane viscosity increased when the transmembrane peptides were incorporated into the membrane. These results suggest that the inclusion of rigid transmembrane structures hinders individual and collective lipid motions by slowing down lipid diffusion and increasing interleaflet coupling. The present study provides a clue for understanding how the local interactions between lipids and proteins change the collective dynamics of the lipid bilayers, and therefore, the function of biological membranes.
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Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Michihiro Nagao
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899-6102, USA; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115, USA; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - Takeshi Yamada
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Koki Imamura
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Koichi Nozaki
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Ramos-Martín F, D'Amelio N. Biomembrane lipids: When physics and chemistry join to shape biological activity. Biochimie 2022; 203:118-138. [PMID: 35926681 DOI: 10.1016/j.biochi.2022.07.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/13/2022] [Accepted: 07/21/2022] [Indexed: 11/02/2022]
Abstract
Biomembranes constitute the first lines of defense of cells. While small molecules can often permeate cell walls in bacteria and plants, they are generally unable to penetrate the barrier constituted by the double layer of phospholipids, unless specific receptors or channels are present. Antimicrobial or cell-penetrating peptides are in fact highly specialized molecules able to bypass this barrier and even discriminate among different cell types. This capacity is made possible by the intrinsic properties of its phospholipids, their distribution between the internal and external leaflet, and their ability to mutually interact, modulating the membrane fluidity and the exposition of key headgroups. Although common phospholipids can be found in the membranes of most organisms, some are characteristic of specific cell types. Here, we review the properties of the most common lipids and describe how they interact with each other in biomembrane. We then discuss how their assembly in bilayers determines some key physical-chemical properties such as permeability, potential and phase status. Finally, we describe how the exposition of specific phospholipids determines the recognition of cell types by membrane-targeting molecules.
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Affiliation(s)
- Francisco Ramos-Martín
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, Amiens, 80039, France.
| | - Nicola D'Amelio
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, Amiens, 80039, France.
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7
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Sixt BS. Host cell death during infection with Chlamydia: a double-edged sword. FEMS Microbiol Rev 2021; 45:5902849. [PMID: 32897321 PMCID: PMC7794043 DOI: 10.1093/femsre/fuaa043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
The phylum Chlamydiae constitutes a group of obligate intracellular bacteria that infect a remarkably diverse range of host species. Some representatives are significant pathogens of clinical or veterinary importance. For instance, Chlamydia trachomatis is the leading infectious cause of blindness and the most common bacterial agent of sexually transmitted diseases. Chlamydiae are exceptionally dependent on their eukaryotic host cells as a consequence of their developmental biology. At the same time, host cell death is an integral part of the chlamydial infection cycle. It is therefore not surprising that the bacteria have evolved exquisite and versatile strategies to modulate host cell survival and death programs to their advantage. The recent introduction of tools for genetic modification of Chlamydia spp., in combination with our increasing awareness of the complexity of regulated cell death in eukaryotic cells, and in particular of its connections to cell-intrinsic immunity, has revived the interest in this virulence trait. However, recent advances also challenged long-standing assumptions and highlighted major knowledge gaps. This review summarizes current knowledge in the field and discusses possible directions for future research, which could lead us to a deeper understanding of Chlamydia's virulence strategies and may even inspire novel therapeutic approaches.
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Affiliation(s)
- Barbara S Sixt
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
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Ambroxol Treatment Suppresses the Proliferation of Chlamydia pneumoniae in Murine Lungs. Microorganisms 2021; 9:microorganisms9040880. [PMID: 33924075 PMCID: PMC8074272 DOI: 10.3390/microorganisms9040880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/16/2021] [Accepted: 04/16/2021] [Indexed: 11/25/2022] Open
Abstract
Ambroxol (Ax) is used as a mucolytics in the treatment of respiratory tract infections. Ax, at a general dose for humans, does not alter Chlamydia pneumoniae growth in mice. Therefore, we aimed to investigate the potential anti-chlamydial effect of Ax at a concentration four timed higher than that used in human medicine. Mice were infected with C. pneumoniae and 5-mg/kg Ax was administered orally. The number of recoverable C. pneumoniae inclusion-forming units (IFUs) in Ax-treated mice was significantly lower than that in untreated mice. mRNA expression levels of several cytokines, including interleukin 12 (IL-12), IL-23, IL-17F, interferon gamma (IFN-γ), and surfactant protein (SP)-A, increased in infected mice treated with Ax. The IFN-γ protein expression levels were also significantly higher in infected and Ax-treated mice. Furthermore, the in vitro results suggested that the ERK 1/2 activity was decreased, which is essential for the C. pneumoniae replication. SP-A and SP-D treatments significantly decreased the number of viable C. pneumoniae IFUs and significantly increased the attachment of C. pneumoniae to macrophage cells. Based on our results, a dose of 5 mg/kg of Ax exhibited an anti-chlamydial effect in mice, probably an immunomodulating effect, and may be used as supporting drug in respiratory infections caused by C. pneumoniae.
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Nakao H, Kimura Y, Sakai A, Ikeda K, Nakano M. Development of membrane-insertable lipid scrambling peptides: A time-resolved small-angle neutron scattering study. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2021; 8:024301. [PMID: 33758768 PMCID: PMC7980860 DOI: 10.1063/4.0000045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/26/2021] [Indexed: 05/14/2023]
Abstract
Phospholipid transbilayer movement (flip-flop) in the plasma membrane is regulated by membrane proteins to maintain cell homeostasis and interact with other cells. The promotion of flip-flop by phospholipid scramblases causes the loss of membrane lipid asymmetry, which is involved in apoptosis, blood coagulation, and viral infection. Therefore, compounds that can artificially control flip-flop in the plasma membrane are of biological and medical interest. Here, we have developed lipid scrambling transmembrane peptides that can be inserted into the membrane. Time-resolved small-angle neutron scattering measurements revealed that the addition of peptides containing a glutamine residue at the center of the hydrophobic sequence to lipid vesicles induces the flip-flop of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. Peptides without the glutamine residue had no effect on the flip-flop. Because the glutamine-containing peptides exhibited scramblase activity in monomeric form, the polar glutamine residue would be exposed to the hydrocarbon region of the membrane, perturbing the membrane and promoting the lipid flip-flop. These scrambling peptides would be valuable tools to regulate lipid flip-flop in the plasma membrane.
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Affiliation(s)
| | | | | | | | - Minoru Nakano
- Author to whom correspondence should be addressed: . Tel.: +81 76 434 7565. Fax: +81 76 434 7568
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Braun C, Hegemann JH, Mölleken K. Insights Into a Chlamydia pneumoniae-Specific Gene Cluster of Membrane Binding Proteins. Front Cell Infect Microbiol 2020; 10:565808. [PMID: 33194804 PMCID: PMC7609445 DOI: 10.3389/fcimb.2020.565808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/23/2020] [Indexed: 11/18/2022] Open
Abstract
Chlamydia pneumoniae is an obligate intracellular pathogen that causes diseases of the upper and lower respiratory tract and is linked to a number of severe and chronic conditions. Here, we describe a large, C. pneumoniae-specific cluster of 13 genes (termed mbp1-13) that encode highly homologous chlamydial proteins sharing the capacity to bind to membranes. The gene cluster is localized on the chromosome between the highly diverse adhesin-encoding pmp genes pmp15 and pmp14. Comparison of human clinical isolates to the predicted ancestral koala isolate indicates that the cluster was acquired in the ancestor and was adapted / modified during evolution. SNPs and IN/DELs within the cluster are specific to isolates taken from different human tissues and show an ongoing adaptation. Most of the cluster proteins harbor one or two domains of unknown function (DUF575 and DUF562). During ectopic expression in human cells these DUF domains are crucial for the association of cluster proteins to the endo-membrane system. Especially DUF575 which harbors a predicted transmembrane domain is important for binding to the membrane, while presence of the DUF562 seems to be of regulatory function. For Mbp1, founding member of the cluster that exhibits a very limited sequence identity to the human Rab36 protein, we found a specific binding to vesicles carrying the early endosomal marker PtdIns(3)P and the endosomal Rab GTPases Rab11 and Rab14. This binding is dependent on a predicted transmembrane domain with an α-helical / β-strand secondary structure, as the mutant version Mbp1mut, which lacks the β-strand secondary structure, shows a reduced association to PtdIns(3)P-positive membranes carrying Rab11 and Rab14. Furthermore, we could not only show that Mbp1 associates with Rab36, but found this specific Rab protein to be recruited to the early C. pneumoniae inclusion. Detection of endogenous Mbp1 and Mbp4 reveal a colocalization to the chlamydial outer membrane protein Momp on EBs. The same colocalization pattern with Momp was observed when we ectopically expressed Mbp4 in C. trachomatis. Thus, we identified a C. pneumoniae-specific cluster of 13 membrane binding proteins (Mbps) localizing to the bacterial outer membrane system.
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Affiliation(s)
- Corinna Braun
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
| | - Johannes H Hegemann
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
| | - Katja Mölleken
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Düsseldorf, Germany
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