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Tezuka T. Microscopic and molecular genetic analyses of morphological development of the actinomycete Actinoplanes missouriensis. Biosci Biotechnol Biochem 2024; 88:857-863. [PMID: 38734887 DOI: 10.1093/bbb/zbae063] [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: 03/18/2024] [Accepted: 05/02/2024] [Indexed: 05/13/2024]
Abstract
The survival strategy of members of the bacterial genus Actinoplanes is fascinating from morphological and evolutionary perspectives. A brief motile phase is incorporated in the filamentous and resting stages of the life cycle of Actinoplanes missouriensis. Spores either lie dormant or swim under different external conditions. This review presents microscopic observations and molecular genetic analyses of A. missouriensis morphological development. Selected examples of the characterization of developmental genes and their products are also introduced.
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Affiliation(s)
- Takeaki Tezuka
- Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo, Japan
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Hu S, Maeda S, Tezuka T, Ohnishi Y. Involvement of a putative acyltransferase gene in sporangium formation in Actinoplanes missouriensis. Microbiol Spectr 2024; 12:e0401023. [PMID: 38501822 PMCID: PMC11064477 DOI: 10.1128/spectrum.04010-23] [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: 11/23/2023] [Accepted: 02/25/2024] [Indexed: 03/20/2024] Open
Abstract
The actinomycete Actinoplanes missouriensis forms branched substrate mycelia during vegetative growth and produces terminal sporangia, each of which contains a few hundred spherical flagellated spores, from the substrate mycelia through short sporangiophores. Based on the observation that remodeling of membrane lipid composition is involved in the morphological development of Streptomyces coelicolor A3(2), we hypothesized that remodeling of membrane lipid composition is also involved in sporangium formation in A. missouriensis. Because some acyltransferases are presumably involved in the remodeling of membrane lipid composition, we disrupted each of the 22 genes annotated as encoding putative acyltransferases in the A. missouriensis genome and evaluated their effects on sporangium formation. The atsA (AMIS_52390) null mutant (ΔatsA) strain formed irregular sporangia of various sizes. Transmission electron microscopy revealed that some ΔatsA sporangiospores did not mature properly. Phase-contrast microscopy revealed that sporangium dehiscence did not proceed properly in the abnormally small sporangia of the ΔatsA strain, whereas apparently normal sporangia opened to release the spores. Consistently, the number of spores released from ΔatsA sporangia was lower than that released from wild-type sporangia. These phenotypic changes were recovered by introducing atsA with its own promoter into the ΔatsA strain. These results demonstrate that AtsA is required for normal sporangium formation in A. missouriensis, although the involvement of AtsA in the remodeling of membrane lipid composition is unlikely because AtsA is an acyltransferase_3 (AT3) protein, which is an integral membrane protein that usually catalyzes the acetylation of cell surface structures.IMPORTANCEActinoplanes missouriensis goes through a life cycle involving complex morphological development, including mycelial growth, sporangium formation and dehiscence, swimming as zoospores, and germination to mycelial growth. In this study, we carried out a comprehensive gene disruption experiment of putative acyltransferase genes to search for acyltransferases involved in the morphological differentiation of A. missouriensis. We revealed that a stand-alone acyltransferase_3 domain-containing protein, named AtsA, is required for normal sporangium formation. Although the molecular mechanism of AtsA in sporangium formation, as well as the enzymatic activity of AtsA, remains to be elucidated, the identification of a putative acyltransferase involved in sporangium formation is significant in the study of morphological development of A. missouriensis. This finding will contribute to our understanding of a complex system for producing sporangia, a rare multicellular organism in bacteria.
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Affiliation(s)
- Shixuan Hu
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Satoshi Maeda
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Tan Z, Tezuka T, Ohnishi Y. Identification of a putative cell wall-hydrolyzing amidase involved in sporangiospore maturation in Actinoplanes missouriensis. J Bacteriol 2024; 206:e0045623. [PMID: 38426722 PMCID: PMC10955841 DOI: 10.1128/jb.00456-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 02/05/2024] [Indexed: 03/02/2024] Open
Abstract
Actinoplanes missouriensis is a filamentous bacterium that differentiates into terminal sporangia, each containing a few hundred spores. Previously, we reported that a cell wall-hydrolyzing N-acetylglucosaminidase, GsmA, is required for the maturation process of sporangiospores in A. missouriensis; sporangia of the gsmA null mutant (ΔgsmA) strain released chains of 2-20 spores under sporangium dehiscence-inducing conditions. In this study, we identified and characterized a putative cell wall hydrolase (AsmA) that is also involved in sporangiospore maturation. AsmA was predicted to have a signal peptide for the general secretion pathway and an N-acetylmuramoyl-l-alanine amidase domain. The transcript level of asmA increased during the early stages of sporangium formation. The asmA null mutant (ΔasmA) strain showed phenotypes similar to those of the wild-type strain, but sporangia of the ΔgsmAΔasmA double mutant released longer spore chains than those from the ΔgsmA sporangia. Furthermore, a weak interaction between AsmA and GsmA was detected in a bacterial two-hybrid assay using Escherichia coli as the host. Based on these results, we propose that AsmA is an enzyme that hydrolyzes peptidoglycan at septum-forming sites to separate adjacent spores during sporangiospore maturation in cooperation with GsmA in A. missouriensis.IMPORTANCEActinoplanes missouriensis produces sporangiospores as dormant cells. The spores inside the sporangia are assumed to be formed from prespores generated by the compartmentalization of intrasporangium hyphae via septation. Previously, we identified GsmA as a cell wall hydrolase responsible for the separation of adjacent spores inside sporangia. However, we predicted that an additional cell wall hydrolase(s) is inevitably involved in the maturation process of sporangiospores because the sporangia of the gsmA null mutant strain released not only tandemly connected spore chains (2-20 spores) but also single spores. In this study, we successfully identified a putative cell wall hydrolase (AsmA) that is involved in sporangiospore maturation in A. missouriensis.
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Affiliation(s)
- Zhuwen Tan
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Akutsu T, Tezuka T, Maruko M, Hirata A, Ohnishi Y. The ssgB gene is required for the early stages of sporangium formation in Actinoplanes missouriensis. J Bacteriol 2024; 206:e0042823. [PMID: 38353530 PMCID: PMC10956132 DOI: 10.1128/jb.00428-23] [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: 12/14/2023] [Accepted: 01/26/2024] [Indexed: 03/22/2024] Open
Abstract
In Streptomyces, multiple paralogs of SsgA-like proteins (SALPs) are involved in spore formation from aerial hyphae. However, the functions of SALPs have not yet been elucidated in other actinobacterial genera. Here, we report the primary function of an SsgB ortholog (AmSsgB) in Actinoplanes missouriensis, which develops terminal sporangia on the substrate mycelia via short sporangiophores. Importantly, AmSsgB is the sole SALP in A. missouriensis. The transcription of AmssgB was upregulated during sporangium formation, consistent with our previous findings that AmssgB is a member of the AmBldD regulon. The AmssgB null mutant (ΔAmssgB) strain formed non-globose irregular structures on the substrate mycelium. Transmission electron microscopy revealed that the irregular structures contained abnormally septate hypha-like cells, without an intrasporangial matrix. These phenotypic changes were restored by complementation with AmssgB. Additionally, analysis of the heterologous expression of seven SALP-encoding genes from Streptomyces coelicolor A3(2) (ssgA-G) in the ΔAmssgB strain revealed that only ssgB could compensate for AmSsgB deficiency. This indicated that SsgB of S. coelicolor A3(2) and AmSsgB have comparable functions in A. missouriensis. In contrast to the ΔAmssgB strain, the ftsZ-disrupted strain showed a severe growth defect and produced small sporangium-like structures that swelled to some extent. These findings indicate that AmSsgB is crucial for the early stages of sporangium formation, not for spore septum formation in the late stages. We propose that AmSsgB is involved in sporangium formation by promoting the expansion of the "presporangium" structures formed on the tips of the substrate hyphae. IMPORTANCE SsgB has been proposed as an archetypical SsgA-like protein with an evolutionarily conserved function in the morphological development of spore-forming actinomycetes. SsgB in Streptomyces coelicolor A3(2) is involved in spore septum formation. However, it is unclear whether this is the primary function of SsgBs in actinobacteria. This study demonstrated that the SsgB ortholog (AmSsgB) in Actinoplanes missouriensis is essential for sporangium expansion, which does not seem to be related to spore septum formation. However, the heterologous expression of ssgB from S. coelicolor A3(2) restored morphological abnormalities in the ΔAmssgB mutant. We propose that the primary function of SsgB is to initiate sporulation in differentiating cells (e.g., aerial hyphae in Streptomyces and "presporangium" cells in A. missouriensis) although its molecular mechanism remains unknown.
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Affiliation(s)
- Takuya Akutsu
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Manato Maruko
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Aiko Hirata
- Bioimaging Center, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Hu S, Tahara YO, Tezuka T, Miyata M, Ohnishi Y. Architecture of Actinoplanes missouriensis sporangia and zoospores visualized using quick-freeze deep-etch electron microscopy. Biosci Biotechnol Biochem 2024; 88:225-229. [PMID: 37974049 DOI: 10.1093/bbb/zbad159] [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: 10/05/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
The architecture of sporangia and zoospores of Actinoplanes missouriensis was analyzed at a high resolution using quick-freeze deep-etch replica electron microscopy. This analysis revealed that (i) sporangia were surrounded by at least 2 membranous layers with smooth surfaces, (ii) zoospores were enclosed by a fibrillar layer, and (iii) flagella were generated in a restricted area on the zoospore surface.
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Affiliation(s)
- Shixuan Hu
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuhei O Tahara
- Department of Biology, Graduate School of Science, Osaka Metropolitan University, Osaka, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Makoto Miyata
- Department of Biology, Graduate School of Science, Osaka Metropolitan University, Osaka, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Tezuka T, Mitsuyama K, Date R, Ohnishi Y. A unique sigma/anti-sigma system in the actinomycete Actinoplanes missouriensis. Nat Commun 2023; 14:8483. [PMID: 38123564 PMCID: PMC10733313 DOI: 10.1038/s41467-023-44291-y] [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: 09/05/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023] Open
Abstract
Bacteria of the genus Actinoplanes form sporangia that contain dormant sporangiospores which, upon contact with water, release motile spores (zoospores) through a process called sporangium dehiscence. Here, we set out to study the molecular mechanisms behind sporangium dehiscence in Actinoplanes missouriensis and discover a sigma/anti-sigma system with unique features. Protein σSsdA contains a functional sigma factor domain and an anti-sigma factor antagonist domain, while protein SipA contains an anti-sigma factor domain and an anti-sigma factor antagonist domain. Remarkably, the two proteins interact with each other via the anti-sigma factor antagonist domain of σSsdA and the anti-sigma factor domain of SipA. Although it remains unclear whether the SipA/σSsdA system plays direct roles in sporangium dehiscence, the system seems to modulate oxidative stress responses in zoospores. In addition, we identify a two-component regulatory system (RsdK-RsdR) that represses initiation of sporangium dehiscence.
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Affiliation(s)
- Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
- Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo, Japan.
| | - Kyota Mitsuyama
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Risa Date
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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Involvement of BldC in the Formation of Physiologically Mature Sporangium in Actinoplanes missouriensis. J Bacteriol 2022; 204:e0018922. [PMID: 36005811 PMCID: PMC9487487 DOI: 10.1128/jb.00189-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AmBldD is a global transcriptional regulator that represses the transcription of several genes required for sporangium formation in Actinoplanes missouriensis. Here, we characterized one of the AmBldD regulons: AMIS_1980, encoding an ortholog of BldC, which is a transcriptional regulator involved in the morphological development of Streptomyces. We determined the transcriptional start point of the bldC ortholog by high-resolution S1 nuclease mapping and found an AmBldD box in its 5'-untranslated region. Reverse transcription-quantitative PCR analysis revealed that the transcription of bldC is activated during sporangium formation. A bldC null mutant (ΔbldC) strain formed normally shaped sporangia, but they exhibited defective sporangium dehiscence; under a dehiscence-inducing condition, the number of spores released from the sporangia of the ΔbldC strain was 2 orders of magnitude lower than that from the sporangia of the wild-type strain. RNA sequencing analysis indicated that BldC functions as a transcriptional activator of several developmental genes, including tcrA, which encodes a key transcriptional activator that regulates sporangium formation, sporangium dehiscence, and spore dormancy. Using electrophoretic mobility shift assay (EMSA), we showed that a recombinant BldC protein directly binds to upstream regions of at least 18 genes, the transcription of which is downregulated in the ΔbldC strain. Furthermore, using DNase I footprinting and EMSA, we demonstrated that BldC binds to the direct repeat sequences containing an AT-rich motif. Thus, BldC is a global regulator that activates the transcription of several genes, some of which are likely to be required for sporangium dehiscence. IMPORTANCE BldC is a global transcriptional regulator that acts as a "brake" in the morphological differentiation of Streptomyces. BldC-like proteins are widely distributed throughout eubacteria, but their orthologs have not been studied outside streptomycetes. Here, we revealed that the BldC ortholog in Actinoplanes missouriensis is essential for sporangium dehiscence and that its regulon is different from the BldC regulon in Streptomyces venezuelae, suggesting that BldC has evolved to play different roles in morphological differentiation between the two genera of filamentous actinomycetes.
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Abstract
Diverse bacterial lifestyle transitions are controlled by the nucleotide second messenger c-di-GMP, including virulence, motility, and biofilm formation. To control such fundamentally distinct processes, the set of genes under c-di-GMP control must have gone through several shifts during bacterial evolution. Here we show that the same σ–(c-di-GMP)–anti-σ switch has been co-opted during evolution to regulate distinct biological functions in unicellular and filamentous bacteria, controlling type IV pilus production in the genus Rubrobacter and the differentiation of reproductive hyphae into spores in Streptomyces. Moreover, we show that the anti-σ likely originated as a homodimer and evolved to become a monomer through an intragenic duplication event. This study thus describes the structural and functional evolution of a c-di-GMP regulatory switch. Filamentous actinobacteria of the genus Streptomyces have a complex lifecycle involving the differentiation of reproductive aerial hyphae into spores. We recently showed c-di-GMP controls this transition by arming a unique anti-σ, RsiG, to bind the sporulation-specific σ, WhiG. The Streptomyces venezuelae RsiG–(c-di-GMP)2–WhiG structure revealed that a monomeric RsiG binds c-di-GMP via two E(X)3S(X)2R(X)3Q(X)3D repeat motifs, one on each helix of an antiparallel coiled-coil. Here we show that RsiG homologs are found scattered throughout the Actinobacteria. Strikingly, RsiGs from unicellular bacteria descending from the most basal branch of the Actinobacteria are small proteins containing only one c-di-GMP binding motif, yet still bind their WhiG partners. Our structure of a Rubrobacter radiotolerans (RsiG)2–(c-di-GMP)2–WhiG complex revealed that these single-motif RsiGs are able to form an antiparallel coiled-coil through homodimerization, thereby allowing them to bind c-di-GMP similar to the monomeric twin-motif RsiGs. Further data show that in the unicellular actinobacterium R. radiotolerans, the (RsiG)2–(c-di-GMP)2–WhiG regulatory switch controls type IV pilus expression. Phylogenetic analysis indicates the single-motif RsiGs likely represent the ancestral state and an internal gene-duplication event gave rise to the twin-motif RsiGs inherited elsewhere in the Actinobacteria. Thus, these studies show how the anti-σ RsiG has evolved through an intragenic duplication event from a small protein carrying a single c-di-GMP binding motif, which functions as a homodimer, to a larger protein carrying two c-di-GMP binding motifs, which functions as a monomer. Consistent with this, our structures reveal potential selective advantages of the monomeric twin-motif anti-σ factors.
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Hashiguchi Y, Tezuka T, Mouri Y, Konishi K, Fujita A, Hirata A, Ohnishi Y. Regulation of Sporangium Formation, Spore Dormancy, and Sporangium Dehiscence by a Hybrid Sensor Histidine Kinase in Actinoplanes missouriensis: Relationship with the Global Transcriptional Regulator TcrA. J Bacteriol 2020; 202:e00228-20. [PMID: 32839172 PMCID: PMC7549356 DOI: 10.1128/jb.00228-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/17/2020] [Indexed: 11/20/2022] Open
Abstract
The rare actinomycete Actinoplanes missouriensis forms terminal sporangia containing a few hundred flagellated spores. In response to water, the sporangia open and release the spores into external environments. The orphan response regulator TcrA functions as a global transcriptional activator during sporangium formation and dehiscence. Here, we report the characterization of an orphan hybrid histidine kinase, HhkA. Sporangia of an hhkA deletion mutant contained many distorted or ectopically germinated spores and scarcely opened to release the spores under sporangium dehiscence-inducing conditions. These phenotypic changes are quite similar to those observed in a tcrA deletion mutant. Comparative RNA sequencing analysis showed that genes controlled by HhkA mostly overlap TcrA-regulated genes. The direct interaction between HhkA and TcrA was suggested by a bacterial two-hybrid assay, but this was not conclusive. The phosphorylation of TcrA using acetyl phosphate as a phosphate donor markedly enhanced its affinity for the TcrA box sequences in the electrophoretic mobility shift assay. Taking these observations together with other results, we proposed that HhkA and TcrA compose a cognate two-component regulatory system, which controls the transcription of the genes involved in many aspects of morphological development, including sporangium formation, spore dormancy, and sporangium dehiscence in A. missouriensisIMPORTANCEActinoplanes missouriensis goes through complex morphological differentiation, including formation of flagellated spore-containing sporangia, sporangium dehiscence, swimming of zoospores, and germination of zoospores to filamentous growth. Although the orphan response regulator TcrA globally activates many genes required for sporangium formation, spore dormancy, and sporangium dehiscence, its partner histidine kinase remained unknown. Here, we analyzed the function of an orphan hybrid histidine kinase, HhkA, and proposed that HhkA constitutes a cognate two-component regulatory system with TcrA. That HhkA and TcrA homologues are highly conserved among the genus Actinoplanes and several closely related rare actinomycetes indicates that this possible two-component regulatory system is employed for complex morphological development in sporangium- and/or zoospore-forming rare actinomycetes.
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Affiliation(s)
- Yuichiro Hashiguchi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Yoshihiro Mouri
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Kenji Konishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Azusa Fujita
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Aiko Hirata
- Bioimaging Center, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Hashiguchi Y, Tezuka T, Ohnishi Y. Involvement of three FliA-family sigma factors in the sporangium formation, spore dormancy and sporangium dehiscence in Actinoplanes missouriensis. Mol Microbiol 2020; 113:1170-1188. [PMID: 32052506 DOI: 10.1111/mmi.14485] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/08/2020] [Accepted: 02/09/2020] [Indexed: 12/27/2022]
Abstract
The rare actinomycete Actinoplanes missouriensis forms sporangia, which open up and release zoospores in response to water. Here, we report a genetic and functional analysis of four FliA-family sigma factors, FliA1, FliA2, FliA3 and FliA4. Transcription of fliA1, fliA2 and fliA3 was directly activated by the global transcriptional activator TcrA during sporangium formation and dehiscence, while fliA4 was almost always transcribed at low levels. Gene disruption analysis showed that (a) deletion of fliA2 reduced the zoospore swimming speed by half, (b) the fliA1-fliA2 double-deletion mutant formed abnormal sporangia in which mutant spores ectopically germinated and (c) deletion of fliA3 induced no phenotypic changes in the wild-type and mutant strains of fliA1 and/or fliA2. Comparative RNA-Seq analyses among the wild-type and gene deletion mutant strains showed probable targets of each FliA-family sigma factor, indicating that FliA1- and FliA2-dependent promoters are quite similar to each other, while the FliA3-dependent promoter is somewhat different. Gene complementation experiments also indicated that the FliA1 regulon overlaps with the FliA2 regulon. These results demonstrate that A. missouriensis has developed a complex transcriptional regulatory network involving multiple FliA-family sigma factors for the accomplishment of its characteristic reproduction process, including sporangium formation, spore dormancy and sporangium dehiscence.
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Affiliation(s)
- Yuichiro Hashiguchi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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11
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Tezuka T, Nakane D, Kimura T, Ohnishi Y. Preparation of Actinoplanes missouriensis Zoospores and Assay for Their Adherence to Solid Surfaces. Bio Protoc 2019; 9:e3458. [PMID: 33654953 DOI: 10.21769/bioprotoc.3458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/17/2019] [Accepted: 11/18/2019] [Indexed: 11/02/2022] Open
Abstract
Spherical zoospores of a rare actinomycete, Actinoplanes missouriensis, adhere to various hydrophobic solid surfaces by means of type IV pili. The purpose of this protocol is to provide detailed descriptions of the preparation of A. missouriensis zoospores and an assay for the adhesion of the zoospores to solid surfaces. This adhesion assay, which measures numbers of zoospores that adhered to the dish surface and swimming zoospores in a tunnel chamber by using a phase-contrast microscope, can also be used for swimming cells of other microorganisms.
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Affiliation(s)
- Takeaki Tezuka
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Daisuke Nakane
- Department of Physics, Gakushuin University, Tokyo, Japan
| | - Tomohiro Kimura
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yasuo Ohnishi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
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Identification and Characterization of a Cell Wall Hydrolase for Sporangiospore Maturation in Actinoplanes missouriensis. J Bacteriol 2019; 201:JB.00519-19. [PMID: 31570527 DOI: 10.1128/jb.00519-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/23/2019] [Indexed: 11/20/2022] Open
Abstract
The rare actinomycete Actinoplanes missouriensis grows as substrate mycelium and forms terminal sporangia containing a few hundred spores as dormant cells. Upon contact with water, the sporangia open up and release spores to external environments. Here, we report a cell wall hydrolase, GsmA, that is required for sporangiospore maturation in A. missouriensis The gsmA gene is conserved among Actinoplanes species and several species of other rare actinomycetes. Transcription of gsmA is activated in the late stage of sporangium formation by the global transcriptional activator TcrA, which is involved in sporangium formation and dehiscence. GsmA is composed of an N-terminal signal peptide for the twin arginine translocation pathway, two tandem bacterial SH3-like domains, and a glucosaminidase domain. Zymographic analysis using a recombinant C-terminal glucosaminidase domain protein showed that GsmA is a hydrolase able to digest cell walls extracted from the vegetative mycelia of A. missouriensis and Streptomyces griseus A gsmA deletion mutant (ΔgsmA) formed apparently normal sporangia, but they released chains of 2 to 20 spores under sporangium dehiscence-inducing conditions, indicating that spores did not completely mature in the mutant sporangia. From these results, we concluded that GsmA is a cell wall hydrolase for digesting peptidoglycan at septum-forming sites to separate adjacent spores during sporangiospore maturation in A. missouriensis Unexpectedly, flagella were observed around the spore chains of the ΔgsmA mutant by transmission electron microscopy. The flagellar formation was strictly restricted to cell-cell interfaces, giving an important insight into the polarity of the flagellar biogenesis in a spherical spore.IMPORTANCE In streptomycetes, an aerial hypha is compartmentalized by multiple septations into prespores, which become spores through a series of maturation processes. However, little is known about these maturation processes. The rare actinomycete Actinoplanes missouriensis produces sporangiospores, which are assumed to be formed also from prespores generated by the compartmentalization of intrasporangium hyphae via septation. The identification of GsmA as a cell wall hydrolase for the separation of adjacent spores sheds light on the almost unknown processes of sporangiospore formation in A. missouriensis Furthermore, the fact that GsmA orthologues are conserved within the genus Actinoplanes but not in streptomycetes indicates that Actinoplanes has developed an original strategy for the spore maturation in a specific environment, that is, inside a sporangium.
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