1
|
Li P, Zhang J, Deng Z, Gao F, Ou HY. Identification and characterization of a central replication origin of the mega-plasmid pSCATT of Streptomyces cattleya. Microbiol Res 2022; 257:126975. [DOI: 10.1016/j.micres.2022.126975] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/17/2022] [Accepted: 01/20/2022] [Indexed: 11/25/2022]
|
2
|
Novakova R, Rückert C, Knirschova R, Feckova L, Busche T, Csolleiova D, Homerova D, Rezuchova B, Javorova R, Sevcikova B, Kalinowski J, Kormanec J. The linear plasmid pSA3239 is essential for the replication of the Streptomyces lavendulae subsp. lavendulae CCM 3239 chromosome. Res Microbiol 2021; 172:103870. [PMID: 34487842 DOI: 10.1016/j.resmic.2021.103870] [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: 05/19/2021] [Revised: 07/16/2021] [Accepted: 07/22/2021] [Indexed: 10/20/2022]
Abstract
We previously reported the complete genome of Streptomyces lavendulae subsp. lavendulae CCM 3239, containing the linear chromosome and the large linear plasmid pSA3239. Although the chromosome exhibited replication features characteristic for the archetypal end-patching replication, it lacked the tap/tpg gene pair for two proteins essential for this process. However, this archetypal tpgSa-tapSa operon is present in pSA3239. Complete genomic sequence of the S. lavendulae Del-LP strain lacking this plasmid revealed the circularization of its chromosome with a large deletion of both arms. These results suggest an essential role of pSA3239-encoded TapSa/TpgSa in the end-patching replication of the chromosome.
Collapse
Affiliation(s)
- Renata Novakova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Christian Rückert
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany.
| | - Renata Knirschova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Lubomira Feckova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Tobias Busche
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany.
| | - Dominika Csolleiova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Dagmar Homerova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Bronislava Rezuchova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Rachel Javorova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Beatrica Sevcikova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany.
| | - Jan Kormanec
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| |
Collapse
|
3
|
Tidjani AR, Bontemps C, Leblond P. Telomeric and sub-telomeric regions undergo rapid turnover within a Streptomyces population. Sci Rep 2020; 10:7720. [PMID: 32382084 PMCID: PMC7205883 DOI: 10.1038/s41598-020-63912-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/07/2020] [Indexed: 11/09/2022] Open
Abstract
Genome dynamics was investigated within natural populations of the soil bacterium Streptomyces. The exploration of a set of closely related strains isolated from micro-habitats of a forest soil exhibited a strong diversity of the terminal structures of the linear chromosome, i.e. terminal inverted repeats (TIRs). Large insertions, deletions and translocations could be observed along with evidence of transfer events between strains. In addition, the telomere and its cognate terminal protein complexes required for terminal replication and chromosome maintenance, were shown to be variable within the population probably reflecting telomere exchanges between the chromosome and other linear replicons (i.e., plasmids). Considering the close genetic relatedness of the strains, these data suggest that the terminal regions are prone to a high turnover due to a high recombination associated with extensive horizontal gene transfer.
Collapse
Affiliation(s)
| | - Cyril Bontemps
- Université de Lorraine, INRAE, DynAMic, F-54000, Nancy, France.
| | - Pierre Leblond
- Université de Lorraine, INRAE, DynAMic, F-54000, Nancy, France.
| |
Collapse
|
4
|
Hashimoto Y, Taniguchi M, Uesaka K, Nomura T, Hirakawa H, Tanimoto K, Tamai K, Ruan G, Zheng B, Tomita H. Novel Multidrug-Resistant Enterococcal Mobile Linear Plasmid pELF1 Encoding vanA and vanM Gene Clusters From a Japanese Vancomycin-Resistant Enterococci Isolate. Front Microbiol 2019; 10:2568. [PMID: 31798546 PMCID: PMC6863802 DOI: 10.3389/fmicb.2019.02568] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/23/2019] [Indexed: 11/13/2022] Open
Abstract
Vancomycin-resistant enterococci are troublesome pathogens in clinical settings because of few treatment options. A VanA/VanM-type vancomycin-resistant Enterococcus faecium clinical isolate was identified in Japan. This strain, named AA708, harbored five plasmids, one of which migrated during agarose gel electrophoresis without S1 nuclease treatment, which is indicative of a linear topology. We named this plasmid pELF1. Whole genome sequencing (WGS) analysis of the AA708 strain revealed that the complete sequence of pELF1 was 143,316 bp long and harbored both the vanA and vanM gene clusters. Furthermore, mfold analysis and WGS data show that the left end of pELF1 presumably forms a hairpin structure, unlike its right end. The pELF1 plasmid was not digested by lambda exonuclease, indicating that terminal proteins were bound to the 5′ end of the plasmid, similar to the Streptomyces linear plasmids. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis results were also consistent with the exonuclease assay results. In retardation assays, DNAs containing the right end of proteinase K-untreated pELF1 did not appear to move as well as the proteinase K-treated pELF1, suggesting that terminal proteins might be attached to the right end of pELF1. Palindromic sequences formed hairpin structures at the right terminal sequence of pELF1; however, sequence similarity with the well-known linear plasmids of Streptomyces spp. was not high. pELF1 was unique as it possessed two different terminal structures. Conjugation experiments revealed that pELF1 could be transferred to E. faecalis, E. faecium, E. casseliflavus, and E. hirae. These transconjugants exhibited not only high resistance levels to vancomycin, but also resistance to streptomycin, kanamycin, and erythromycin. These results indicate that pELF1 has the ability to confer multidrug resistance to Enterococcus spp. simultaneously, which might lead to clinical hazards.
Collapse
Affiliation(s)
- Yusuke Hashimoto
- Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Makoto Taniguchi
- Oral Microbiome Center, Taniguchi Dental Clinic, Takamatsu, Japan
| | - Kazuma Uesaka
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Takahiro Nomura
- Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Hidetada Hirakawa
- Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Koichi Tanimoto
- Laboratory of Bacterial Drug Resistance, Gunma University Graduate School of Medicine, Maebashi, Japan
| | | | - Genjie Ruan
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, China
| | - Bo Zheng
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, China
| | - Haruyoshi Tomita
- Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Japan.,Laboratory of Bacterial Drug Resistance, Gunma University Graduate School of Medicine, Maebashi, Japan
| |
Collapse
|
5
|
Yano H, Shintani M, Tomita M, Suzuki H, Oshima T. Reconsidering plasmid maintenance factors for computational plasmid design. Comput Struct Biotechnol J 2018; 17:70-81. [PMID: 30619542 PMCID: PMC6312765 DOI: 10.1016/j.csbj.2018.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/08/2018] [Accepted: 12/09/2018] [Indexed: 12/18/2022] Open
Abstract
Plasmids are genetic parasites of microorganisms. The genomes of naturally occurring plasmids are expected to be polished via natural selection to achieve long-term persistence in the microbial cell population. However, plasmid genomes are extremely diverse, and the rules governing plasmid genomes are not fully understood. Therefore, computationally designing plasmid genomes optimized for model and nonmodel organisms remains challenging. Here, we summarize current knowledge of the plasmid genome organization and the factors that can affect plasmid persistence, with the aim of constructing synthetic plasmids for use in gram-negative bacteria. Then, we introduce publicly available resources, plasmid data, and bioinformatics tools that are useful for computational plasmid design.
Collapse
Affiliation(s)
- Hirokazu Yano
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Masaki Shintani
- Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1, Hamamatsu 432-8561, Japan
- Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 3-5-1, Hamamatsu 432-8561, Japan
| | - Masaru Tomita
- Institute for Advanced Biosciences, Keio University, 14-1, Baba-cho, Tsuruoka, Yamagata 997-0035, Japan
- Faculty of Environment and Information Studies, Keio University, 5322, Endo, Fujisawa, Kanagawa 252-0882, Japan
| | - Haruo Suzuki
- Institute for Advanced Biosciences, Keio University, 14-1, Baba-cho, Tsuruoka, Yamagata 997-0035, Japan
- Faculty of Environment and Information Studies, Keio University, 5322, Endo, Fujisawa, Kanagawa 252-0882, Japan
| | - Taku Oshima
- Department of Biotechnology, Toyama Prefectural University, 5180, Kurokawa, Imizu, Toyama 939-0398, Japan
| |
Collapse
|
6
|
Mingyar E, Novakova R, Knirschova R, Feckova L, Bekeova C, Kormanec J. Unusual features of the large linear plasmid pSA3239 from Streptomyces aureofaciens CCM 3239. Gene 2017; 642:313-323. [PMID: 29155332 DOI: 10.1016/j.gene.2017.11.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 11/17/2022]
Abstract
We previously identified the aur1 gene cluster, responsible for the production of the angucycline antibiotic auricin in Streptomyces aureofaciens CCM 3239. Pulse-field gel electrophoresis showed a single, 241kb linear plasmid, pSA3239, in this strain, and several approaches confirmed the presence of the aur1 cluster in this plasmid. We report here the nucleotide sequence of this 241,076-bp plasmid. pSA3239 contains an unprecedentedly small (13bp) telomeric sequence CCCGCGGAGCGGG, which is identical to the conserved Palindrome I sequence involved in the priming of end-patching replication. A bioinformatics analysis revealed 234 open reading frames with high number (28) of regulatory genes from various families. In contrast to most other linear plasmids, pSA3239 contains a pair of replication initiation genes (sa76 and sa75) located at its extreme left end, adjacent to the telomere. Together with similar proteins from several other linear plasmids (pFRL2, pSLA2-M, pSV2, pSDA1, and SAP1), they constitute a new family of replication initiation proteins. This left end also contains two genes, tpgSa and tapSa, encoding the terminal protein and the telomere associated-protein involved in telomere end-patching replication. pSA3239 also contains two genes homologous to the parAB partitioning system, and deletion of the parA homologue (sa43) affects structural stability of the plasmid. pSA3239 carries five potential secondary metabolite gene clusters. In addition to aur1 and a non-ribosomal peptide synthase (NRPS) gene cluster for the blue pigment indigoidine, it also contains a partial type II polyketide synthase (PKS) gene cluster, a partial type I PKS gene cluster, and a NRPS/PKSI gene cluster for unknown secondary metabolites. The last gene cluster contains a subcluster of seven genes (sa91-sa97), highly similar to part of the valanimycin biosynthetic cluster vlm. A S. aureofaciens strain lacking pSA3239 was prepared. This deletion did not substantially affect growth and differentiation. A comparative analysis of secondary metabolites between both strains did not identify any product, except auricin and indigoidine, which is dependent upon pSA3239. Thus, the other three identified gene clusters are likely silent under these conditions.
Collapse
Affiliation(s)
- Erik Mingyar
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic
| | - Renata Novakova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic
| | - Renata Knirschova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic
| | - Lubomira Feckova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic
| | - Carmen Bekeova
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic
| | - Jan Kormanec
- Institute of Molecular Biology, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic.
| |
Collapse
|
7
|
Yang CC, Tseng SM, Pan HY, Huang CH, Chen CW. Telomere associated primase Tap repairs truncated telomeres of Streptomyces. Nucleic Acids Res 2017; 45:5838-5849. [PMID: 28369604 PMCID: PMC5449611 DOI: 10.1093/nar/gkx189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/11/2017] [Indexed: 01/01/2023] Open
Abstract
Replication of the linear chromosomes of soil bacteria Streptomyces proceeds from an internal origin towards the telomeres, followed by patching of the resulting terminal single-strand overhangs by DNA synthesis using terminal proteins as the primer, which remains covalently bound to the 5΄ ends of the DNA. In most Streptomyces chromosomes, the end patching requires the single-strand overhangs, terminal protein Tpg, and terminal associated protein Tap. The telomere overhangs contain several palindromic sequences capable of forming stable hairpins. Previous in vitro deoxynucleotidylation studies indicated that Tap adds the Palindrome I sequence to Tpg, which is extended by a polymerase to fill the gap. In this study, the stringency of Palindrome I sequence was examined by an in vitro deoxynucleotidylation system and in vivo replication. Several nt in Palindrome I were identified to be critical for priming. While the first 3 G on the template were required for deoxynucleotidylation in vitro, deletions of them could be suppressed by the presence of dGTP. In vivo, deletions of these G were also tolerated, and the telomere sequence was restored in the linear plasmid DNA. Our results indicated that the truncated telomeres were repaired by extension synthesis by Tap on the foldback Palindrome I sequence.
Collapse
Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
- To whom correspondence should be addressed. Tel: +886 3 2653303; Fax: +886 3 2653399;
| | - Shu-Min Tseng
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Hung-Yin Pan
- Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Chih-Hung Huang
- Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Carton W. Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
| |
Collapse
|
8
|
Salas M, Holguera I, Redrejo-Rodríguez M, de Vega M. DNA-Binding Proteins Essential for Protein-Primed Bacteriophage Φ29 DNA Replication. Front Mol Biosci 2016; 3:37. [PMID: 27547754 PMCID: PMC4974454 DOI: 10.3389/fmolb.2016.00037] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/20/2016] [Indexed: 01/25/2023] Open
Abstract
Bacillus subtilis phage Φ29 has a linear, double-stranded DNA 19 kb long with an inverted terminal repeat of 6 nucleotides and a protein covalently linked to the 5′ ends of the DNA. This protein, called terminal protein (TP), is the primer for the initiation of replication, a reaction catalyzed by the viral DNA polymerase at the two DNA ends. The DNA polymerase further elongates the nascent DNA chain in a processive manner, coupling strand displacement with elongation. The viral protein p5 is a single-stranded DNA binding protein (SSB) that binds to the single strands generated by strand displacement during the elongation process. Viral protein p6 is a double-stranded DNA binding protein (DBP) that preferentially binds to the origins of replication at the Φ29 DNA ends and is required for the initiation of replication. Both SSB and DBP are essential for Φ29 DNA amplification. This review focuses on the role of these phage DNA-binding proteins in Φ29 DNA replication both in vitro and in vivo, as well as on the implication of several B. subtilis DNA-binding proteins in different processes of the viral cycle. We will revise the enzymatic activities of the Φ29 DNA polymerase: TP-deoxynucleotidylation, processive DNA polymerization coupled to strand displacement, 3′–5′ exonucleolysis and pyrophosphorolysis. The resolution of the Φ29 DNA polymerase structure has shed light on the translocation mechanism and the determinants responsible for processivity and strand displacement. These two properties have made Φ29 DNA polymerase one of the main enzymes used in the current DNA amplification technologies. The determination of the structure of Φ29 TP revealed the existence of three domains: the priming domain, where the primer residue Ser232, as well as Phe230, involved in the determination of the initiating nucleotide, are located, the intermediate domain, involved in DNA polymerase binding, and the N-terminal domain, responsible for DNA binding and localization of the TP at the bacterial nucleoid, where viral DNA replication takes place. The biochemical properties of the Φ29 DBP and SSB and their function in the initiation and elongation of Φ29 DNA replication, respectively, will be described.
Collapse
Affiliation(s)
- Margarita Salas
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas), Universidad Autónoma de Madrid Madrid, Spain
| | - Isabel Holguera
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas), Universidad Autónoma de Madrid Madrid, Spain
| | - Modesto Redrejo-Rodríguez
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas), Universidad Autónoma de Madrid Madrid, Spain
| | - Miguel de Vega
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas), Universidad Autónoma de Madrid Madrid, Spain
| |
Collapse
|
9
|
Yang CC, Tseng SM, Chen CW. Telomere-associated proteins add deoxynucleotides to terminal proteins during replication of the telomeres of linear chromosomes and plasmids in Streptomyces. Nucleic Acids Res 2015; 43:6373-83. [PMID: 25883134 PMCID: PMC4513846 DOI: 10.1093/nar/gkv302] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/17/2015] [Accepted: 03/25/2015] [Indexed: 12/15/2022] Open
Abstract
Typical telomeres of linear chromosomes and plasmids of soil bacteria Streptomyces consist of tightly packed palindromic sequences with a terminal protein ('TP') covalently attached to the 5' end of the DNA. Replication of these linear replicons is initiated internally and proceeds bidirectionally toward the telomeres, which leaves single-strand overhangs at the 3' ends. These overhangs are filled by DNA synthesis using the TPs as the primers ('end patching'). The gene encoding for typical TP, tpg, forms an operon with tap, encoding an essential telomere-associated protein, which binds TP and the secondary structures formed by the 3' overhangs. Previously one of the two translesion synthesis DNA polymerases, DinB1 or DinB2, was proposed to catalyze the protein-primed synthesis. However, using an in vitro end-patching system, we discovered that Tpg and Tap alone could carry out the protein-primed synthesis to a length of 13 nt. Similarly, an 'atypical' terminal protein, Tpc, and its cognate telomere-associated protein, Tac, of SCP1 plasmid, were sufficient to achieve protein-primed synthesis in the absence of additional polymerase. These results indicate that these two telomere-associated proteins possess polymerase activities alone or in complex with the cognate TPs.
Collapse
Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li 32023, Taiwan
| | - Shu-Min Tseng
- Department of Chemistry, Chung-Yuan Christian University, Chung-li 32023, Taiwan
| | - Carton W Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 11221, Taiwan
| |
Collapse
|
10
|
Raftis EJ, Forde BM, Claesson MJ, O'Toole PW. Unusual genome complexity in Lactobacillus salivarius JCM1046. BMC Genomics 2014; 15:771. [PMID: 25201645 PMCID: PMC4165912 DOI: 10.1186/1471-2164-15-771] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/26/2014] [Indexed: 12/31/2022] Open
Abstract
Background Lactobacillus salivarius strains are increasingly being exploited for their probiotic properties in humans and animals. Dissemination of antibiotic resistance genes among species with food or probiotic-association is undesirable and is often mediated by plasmids or integrative and conjugative elements. L. salivarius strains typically have multireplicon genomes including circular megaplasmids that encode strain-specific traits for intestinal survival and probiotic activity. Linear plasmids are less common in lactobacilli and show a very limited distribution in L. salivarius. Here we present experimental evidence that supports an unusually complex multireplicon genome structure in the porcine isolate L. salivarius JCM1046. Results JCM1046 harbours a 1.83 Mb chromosome, and four plasmids which constitute 20% of the genome. In addition to the known 219 kb repA-type megaplasmid pMP1046A, we identified and experimentally validated the topology of three additional replicons, the circular pMP1046B (129 kb), a linear plasmid pLMP1046 (101 kb) and pCTN1046 (33 kb) harbouring a conjugative transposon. pMP1046B harbours both plasmid-associated replication genes and paralogues of chromosomally encoded housekeeping and information-processing related genes, thus qualifying it as a putative chromid. pLMP1046 shares limited sequence homology or gene synteny with other L. salivarius plasmids, and its putative replication-associated protein is homologous to the RepA/E proteins found in the large circular megaplasmids of L. salivarius. Plasmid pCTN1046 harbours a single copy of an integrated conjugative transposon (Tn6224) which appears to be functionally intact and includes the tetracycline resistance gene tetM. Conclusion Experimental validation of sequence assemblies and plasmid topology resolved the complex genome architecture of L. salivarius JCM1046. A high-coverage draft genome sequence would not have elucidated the genome complexity in this strain. Given the expanding use of L. salivarius as a probiotic, it is important to determine the genotypic and phenotypic organization of L. salivarius strains. The identification of Tn6224-like elements in this species has implications for strain selection for probiotic applications. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-771) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
| | | | | | - Paul W O'Toole
- School of Microbiology University College Cork, Cork, Ireland.
| |
Collapse
|
11
|
Gella P, Salas M, Mencía M. Improved artificial origins for phage Φ29 terminal protein-primed replication. Insights into early replication events. Nucleic Acids Res 2014; 42:9792-806. [PMID: 25081208 PMCID: PMC4150772 DOI: 10.1093/nar/gku660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The replication machinery of bacteriophage Φ29 is a paradigm for protein-primed replication and it holds great potential for applied purposes. To better understand the early replication events and to find improved origins for DNA amplification based on the Φ29 system, we have studied the end-structure of a double-stranded DNA replication origin. We have observed that the strength of the origin is determined by a combination of factors. The strongest origin (30-fold respect to wt) has the sequence CCC at the 3' end of the template strand, AAA at the 5' end of the non-template strand and 6 nucleotides as optimal unpairing at the end of the origin. We also show that the presence of a correctly positioned displaced strand is important because origins with 5' or 3' ssDNA regions have very low activity. Most of the effect of the improved origins takes place at the passage between the terminal protein-primed and the DNA-primed modes of replication by the DNA polymerase suggesting the existence of a thermodynamic barrier at that point. We suggest that the template and non-template strands of the origin and the TP/DNA polymerase complex form series of interactions that control the critical start of terminal protein-primed replication.
Collapse
Affiliation(s)
- Pablo Gella
- Centro de Biología Molecular "Severo Ochoa" (Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Margarita Salas
- Centro de Biología Molecular "Severo Ochoa" (Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Mario Mencía
- Centro de Biología Molecular "Severo Ochoa" (Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| |
Collapse
|
12
|
Holguera I, Redrejo-Rodríguez M, Salas M, Muñoz-Espín D. New insights in the ϕ29 terminal protein DNA-binding and host nucleoid localization functions. Mol Microbiol 2013; 91:232-41. [PMID: 24205926 DOI: 10.1111/mmi.12456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2013] [Indexed: 11/30/2022]
Abstract
Protein-primed DNA replication constitutes a strategy to initiate viral DNA synthesis in a variety of prokaryotic and eukaryotic organisms. Although the main function of viral terminal proteins (TPs) is to provide a free hydroxyl group to start initiation of DNA replication, there are compelling evidences that TPs can also play other biological roles. In the case of Bacillus subtilis bacteriophage ϕ29, the N-terminal domain of the TP organizes viral DNA replication at the bacterial nucleoid being essential for an efficient phage DNA replication, and it contains a nuclear localization signal (NLS) that is functional in eukaryotes. Here we provide information about the structural properties of the ϕ29 TP N-terminal domain, which possesses sequence-independent DNA-binding capacity, and dissect the amino acid residues important for its biological function. By mutating all the basic residues of the TP N-terminal domain we identify the amino acids responsible for its interaction with the B. subtilis genome, establishing a correlation between the capacity of DNA-binding and nucleoid localization of the protein. Significantly, these residues are important to recruit the DNA polymerase at the bacterial nucleoid and, subsequently, for an efficient phage DNA replication.
Collapse
Affiliation(s)
- Isabel Holguera
- Instituto de Biología Molecular 'Eladio Viñuela' (Consejo Superior de Investigaciones Científicas), Centro de Biología Molecular 'Severo Ochoa' (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049, Madrid, Spain
| | | | | | | |
Collapse
|
13
|
Peng S, Zeng A, Zhong L, Zhang R, Zhou M, Cheng Q, Zhao L, Wang T, Tan H, Qin Z. Three functional replication origins of the linear and artificially circularized plasmid SCP1 of Streptomyces coelicolor. Microbiology (Reading) 2013; 159:2127-2140. [DOI: 10.1099/mic.0.067363-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Shiyuan Peng
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Ana Zeng
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Li Zhong
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Ran Zhang
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Min Zhou
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Qiuxiang Cheng
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Liqian Zhao
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Tao Wang
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Huarong Tan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Zhongjun Qin
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, PR China
| |
Collapse
|
14
|
Nindita Y, Nishikawa T, Arakawa K, Wang G, Ochi K, Qin Z, Kinashi H. Chromosomal circularization of the model Streptomyces species, Streptomyces coelicolor A3(2). FEMS Microbiol Lett 2013; 347:149-55. [PMID: 23915258 DOI: 10.1111/1574-6968.12228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/10/2013] [Accepted: 07/30/2013] [Indexed: 12/14/2022] Open
Abstract
Streptomyces linear chromosomes frequently cause deletions at both ends spontaneously or by various mutagenic treatments, leading to chromosomal circularization and arm replacement. However, chromosomal circularization has not been confirmed at a sequence level in the model species, Streptomyces coelicolor A3(2). In this work, we have cloned and sequenced a fusion junction of a circularized chromosome in an S. coelicolor A3(2) mutant and found a 6-bp overlap between the left and right deletion ends. This result shows that chromosomal circularization occurred by nonhomologous recombination of the deletion ends in this species, too. At the end of the study, we discuss on stability and evolution of Streptomyces chromosomes.
Collapse
Affiliation(s)
- Yosi Nindita
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan
| | | | | | | | | | | | | |
Collapse
|
15
|
Zhang R, Xia H, Xu Q, Dang F, Qin Z. Recombinational cloning of the antibiotic biosynthetic gene clusters in linear plasmid SCP1 ofStreptomyces coelicolorA3(2). FEMS Microbiol Lett 2013; 345:39-48. [DOI: 10.1111/1574-6968.12183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 04/19/2013] [Accepted: 05/17/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
- Ran Zhang
- Key laboratory of Synthetic Biology; Shanghai Institute of Plant Physiology and Ecology; Shanghai Institutes for Biological Sciences; the Chinese Academy of Sciences; Shanghai; China
| | - Haiyang Xia
- Key laboratory of Synthetic Biology; Shanghai Institute of Plant Physiology and Ecology; Shanghai Institutes for Biological Sciences; the Chinese Academy of Sciences; Shanghai; China
| | - Qingyu Xu
- Key laboratory of Synthetic Biology; Shanghai Institute of Plant Physiology and Ecology; Shanghai Institutes for Biological Sciences; the Chinese Academy of Sciences; Shanghai; China
| | - Fujun Dang
- Key laboratory of Synthetic Biology; Shanghai Institute of Plant Physiology and Ecology; Shanghai Institutes for Biological Sciences; the Chinese Academy of Sciences; Shanghai; China
| | - Zhongjun Qin
- Key laboratory of Synthetic Biology; Shanghai Institute of Plant Physiology and Ecology; Shanghai Institutes for Biological Sciences; the Chinese Academy of Sciences; Shanghai; China
| |
Collapse
|
16
|
PH1: an archaeovirus of Haloarcula hispanica related to SH1 and HHIV-2. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2013; 2013:456318. [PMID: 23585730 PMCID: PMC3622292 DOI: 10.1155/2013/456318] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/07/2013] [Indexed: 11/24/2022]
Abstract
Halovirus PH1 infects Haloarcula hispanica and was isolated from an Australian salt lake. The burst size in single-step growth conditions was 50–100 PFU/cell, but cell density did not decrease until well after the rise (4–6 hr p.i.), indicating that the virus could exit without cell lysis. Virions were round, 51 nm in diameter, displayed a layered capsid structure, and were sensitive to chloroform and lowered salt concentration. The genome is linear dsDNA, 28,064 bp in length, with 337 bp terminal repeats and terminal proteins, and could transfect haloarchaeal species belonging to five different genera. The genome is predicted to carry 49 ORFs, including those for structural proteins, several of which were identified by mass spectroscopy. The close similarity of PH1 to SH1 (74% nucleotide identity) allowed a detailed description and analysis of the differences (divergent regions) between the two genomes, including the detection of repeat-mediated deletions. The relationship of SH1-like and pleolipoviruses to previously described genomic loci of virus and plasmid-related elements (ViPREs) of haloarchaea revealed an extensive level of recombination between the known haloviruses. PH1 is a member of the same virus group as SH1 and HHIV-2, and we propose the name halosphaerovirus to accommodate these viruses.
Collapse
|
17
|
Novakova R, Knirschova R, Farkasovsky M, Feckova L, Rehakova A, Mingyar E, Kormanec J. The gene clusteraur1for the angucycline antibiotic auricin is located on a large linear plasmid pSA3239 inStreptomyces aureofaciensCCM 3239. FEMS Microbiol Lett 2013; 342:130-7. [DOI: 10.1111/1574-6968.12095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/28/2013] [Indexed: 11/28/2022] Open
Affiliation(s)
- Renata Novakova
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Renata Knirschova
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Marian Farkasovsky
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Lubomira Feckova
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Alena Rehakova
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Erik Mingyar
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| | - Jan Kormanec
- Institute of Molecular Biology; Slovak Academy of Sciences; Bratislava; Slovak Republic
| |
Collapse
|
18
|
Wang T, Chen Z, Cheng Q, Zhou M, Tian X, Xie P, Zhong L, Shen M, Qin Z. Characterization of replication and conjugation of plasmid pWTY27 from a widely distributed Streptomyces species. BMC Microbiol 2012; 12:253. [PMID: 23134842 PMCID: PMC3583192 DOI: 10.1186/1471-2180-12-253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 10/26/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Streptomyces species are widely distributed in natural habitats, such as soils, lakes, plants and some extreme environments. Replication loci of several Streptomyces theta-type plasmids have been reported, but are not characterized in details. Conjugation loci of some Streptomyces rolling-circle-type plasmids are identified and mechanism of conjugal transferring are described. RESULTS We report the detection of a widely distributed Streptomyces strain Y27 and its indigenous plasmid pWTY27 from fourteen plants and four soil samples cross China by both culturing and nonculturing methods. The complete nucleotide sequence of pWTY27 consisted of 14,288 bp. A basic locus for plasmid replication comprised repAB genes and an adjacent iteron sequence, to a long inverted-repeat (ca. 105 bp) of which the RepA protein bound specifically in vitro, suggesting that RepA may recognize a second structure (e.g. a long stem-loop) of the iteron DNA. A plasmid containing the locus propagated in linear mode when the telomeres of a linear plasmid were attached, indicating a bi-directional replication mode for pWTY27. As for rolling-circle plasmids, a single traA gene and a clt sequence (covering 16 bp within traA and its adjacent 159 bp) on pWTY27 were required for plasmid transfer. TraA recognized and bound specifically to the two regions of the clt sequence, one containing all the four DC1 of 7 bp (TGACACC) and one DC2 (CCCGCCC) and most of IC1, and another covering two DC2 and part of IC1, suggesting formation of a high-ordered DNA-protein complex. CONCLUSIONS This work (i) isolates a widespread Streptomyces strain Y27 and sequences its indigenous theta-type plasmid pWTY27; (ii) identifies the replication and conjugation loci of pWTY27 and; (iii) characterizes the binding sequences of the RepA and TraA proteins.
Collapse
Affiliation(s)
- Tao Wang
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Guo P, Cheng Q, Xie P, Fan Y, Jiang W, Qin Z. Characterization of the multiple CRISPR loci on Streptomyces linear plasmid pSHK1. Acta Biochim Biophys Sin (Shanghai) 2011; 43:630-9. [PMID: 21705768 DOI: 10.1093/abbs/gmr052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The complete nucleotide sequence including the novel telomere sequence of Streptomyces linear plasmid pSHK1 consists of 187,263-bp, 158 genes, in which 51 genes resemble those of the linear plasmid SCP1 of Streptomyces coelicolor A3(2), and 20 genes encode transposases. Strikingly, the repetitive CRISPRs (clustered regularly interspaced short palindromic repeats) and cas (CRISPR-associated) genes were found, including a cluster of eight cas genes, in the order cas2B-cas1B-cas3B-cas5-cas4-cas2A-cas1A-cas3A, bracketed by a pair of divergent CRISPRs, and five other dispersed CRISPRs. The cas2B-cas1B-cas3B-cas5 or cas4-cas2A-cas1A genes were co-transcribed. Protein-protein interactions between Cas5 and Cas1A, 2A, 2B, 3B were detected by yeast two-hybrids, indicating a critical role of Cas5 for the formation of protein complexes. By polymerase chain reaction and Southern hybridization, 12 cas4 genes including three on linear plasmids were found among 75 newly isolated Streptomyces strains. The paired-CRISPRs and bracketed cas were also conserved in several other Streptomyces or actinomycete species. However, unlike other bacteria, the CRISPRs-cas in pSHK1 could not provide immunity against introduction of phage ΦC31 and plasmid containing the particular spacers in Streptomyces.
Collapse
Affiliation(s)
- Peng Guo
- Key Laboratory of Synthetic Biology, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | | | | | | | | | | |
Collapse
|
20
|
pSLA2-M of Streptomyces rochei is a composite linear plasmid characterized by self-defense genes and homology with pSLA2-L. Biosci Biotechnol Biochem 2011; 75:1147-53. [PMID: 21670526 DOI: 10.1271/bbb.110054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The 113,463-bp nucleotide sequence of the linear plasmid pSLA2-M of Streptomyces rochei 7434AN4 was determined. pSLA2-M had a 69.7% overall GC content, 352-bp terminal inverted repeats with 91% (321/352) identity at both ends, and 121 open reading frames. The rightmost 14.6-kb sequence was almost (14,550/14,555) identical to that of the coexisting 211-kb linear plasmid pSLA2-L. Adjacent to this homologous region an 11.8-kb CRISPR cluster was identified, which is known to function against phage infection in prokaryotes. This cluster region as well as another one containing two large membrane protein genes (orf78 and orf79) were flanked by direct repeats of 194 and 566 bp respectively. Hence the insertion of circular DNAs containing each cluster by homologous recombination was suggested. In addition, the orf71 encoded a Ku70/Ku80-like protein, known to function in the repair of double-strand DNA breaks in eukaryotes, but disruption of it did not affect the radiation sensitivity of the mutant. A pair of replication initiation genes (orf1-orf2) were identified at the extreme left end. Thus, pSLA2-M proved to be a composite linear plasmid characterized by self-defense genes and homology with pSLA2-L that might have been generated by multiple recombination events.
Collapse
|
21
|
Wagenknecht M, Meinhardt F. Replication-involved genes of pAL1, the linear plasmid of Arthrobacter nitroguajacolicus Rü61a--phylogenetic and transcriptional analysis. Plasmid 2010; 65:176-84. [PMID: 21185858 DOI: 10.1016/j.plasmid.2010.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 12/16/2010] [Accepted: 12/17/2010] [Indexed: 11/28/2022]
Abstract
The 113-kb pAL1 is the only Arthrobacter linear plasmid known; it has terminal inverted repeats and 5' covalently attached terminal proteins (TPs). The latter and a telomere-associated protein (Tap) are encoded by plasmid ORFs 102 and 101, respectively. As for Streptomyces linear replicons, in which both above proteins are instrumental in telomere patching, they are involved in pAL1 replication as well. However, the alignment of actinobacterial Taps and TPs revealed that pAL1 and the linear elements from Rhodococci comprise a discrete phylogenetic group, clearly delineated from the streptomycetes linear plasmids. In line with such findings is the same genetic arrangement of ORF 101 and 102 counterparts in the rhodococcal elements. Furthermore, the adjacent gene (ORF100) has matches in the rhodococcal plasmids as well. In linear elements of Streptomyces there is no ORF100 homolog. Two alternative annotations are possible for ORF100 gene products. As RT-PCR revealed cotranscription of ORFs 100-102, the ORF100 gene product is presumably involved in replicative processes. Taken also into consideration the likely absence of an internal replication origin (other than in Streptomyces linear elements), we assume a distinct replication/telomere patching mechanism for pAL1 type replicons.
Collapse
Affiliation(s)
- Martin Wagenknecht
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstr. 3, D-48149 Münster, Germany
| | | |
Collapse
|
22
|
Tsai HH, Huang CH, Tessmer I, Erie DA, Chen CW. Linear Streptomyces plasmids form superhelical circles through interactions between their terminal proteins. Nucleic Acids Res 2010; 39:2165-74. [PMID: 21109537 PMCID: PMC3064793 DOI: 10.1093/nar/gkq1204] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Linear chromosomes and linear plasmids of Streptomyces possess covalently bound terminal proteins (TPs) at the 5′ ends of their telomeres. These TPs are proposed to act as primers for DNA synthesis that patches the single-stranded gaps at the 3′ ends during replication. Most (‘archetypal’) Streptomyces TPs (designated Tpg) are highly conserved in size and sequence. In addition, there are a number of atypical TPs with heterologous sequences and sizes, one of which is Tpc that caps SCP1 plasmid of Streptomyces coelicolor. Interactions between the TPs on the linear Streptomyces replicons have been suggested by electrophoretic behaviors of TP-capped DNA and circular genetic maps of Streptomyces chromosomes. Using chemical cross-linking, we demonstrated intramolecular and intermolecular interactions in vivo between Tpgs, between Tpcs and between Tpg and Tpc. Interactions between the chromosomal and plasmid telomeres were also detected in vivo. The intramolecular telomere interactions produced negative superhelicity in the linear DNA, which was relaxed by topoisomerase I. Such intramolecular association between the TPs poses a post-replicational complication in the formation of a pseudo-dimeric structure that requires resolution by exchanging TPs or DNA.
Collapse
Affiliation(s)
- Hsiu-Hui Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan
| | | | | | | | | |
Collapse
|
23
|
A novel replicative enzyme encoded by the linear Arthrobacter plasmid pAL1. J Bacteriol 2010; 192:4935-43. [PMID: 20675469 DOI: 10.1128/jb.00614-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The soil bacterium Arthrobacter nitroguajacolicus Rü61a contains the linear plasmid pAL1, which codes for the degradation of 2-methylquinoline. Like other linear replicons of actinomycetes, pAL1 is characterized by short terminal inverted-repeat sequences and terminal proteins (TPpAL1) covalently attached to its 5' ends. TPpAL1, encoded by the pAL1.102 gene, interacts in vivo with the protein encoded by pAL1.101. Bioinformatic analysis of the pAL1.101 protein, which comprises 1,707 amino acids, suggested putative zinc finger and topoisomerase-primase domains and part of a superfamily 2 helicase domain in its N-terminal and central regions, respectively. Sequence motifs characteristic of the polymerization domain of family B DNA polymerases are partially conserved in a C-terminal segment. The purified recombinant protein catalyzed the deoxycytidylation of TPpAL1 in the presence of single-stranded DNA templates comprising the 3'-terminal sequence (5'-GCAGG-3'), which in pAL1 forms the terminal inverted repeat, but also at templates with 5'-(G/T)CA(GG/GC/CG)-3' ends. Enzyme assays suggested that the protein exhibits DNA topoisomerase, DNA helicase, and DNA- and protein-primed DNA polymerase activities. The pAL1.101 protein, therefore, may act as a replicase of pAL1.
Collapse
|
24
|
Two internal origins of replication in Streptomyces linear plasmid pFRL1. Appl Environ Microbiol 2010; 76:5676-83. [PMID: 20601502 DOI: 10.1128/aem.02905-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous reports showed that Streptomyces linear plasmids usually contain one internal replication locus. Here, we identified two new replication loci on pFRL1, one (rep1A-ncs1) next to a telomere and another (rep2A-ncs2) approximately 10 kb from it. The rep1A-ncs1 locus was able to direct replication independently in both linear and circular modes, whereas rep2A-ncs2 required an additional locus, rlrA-rorA, in order to direct propagation in linear mode. Rep1A protein bound to ncs1 in vitro. By quantitative reverse transcription-PCR and Northern hybridization, we showed that transcription of rep1A and rep2A varied during development and that each dominated at different time points. pFRL1-derived linear plasmids were inherited through spores more stably than circular plasmids and were more stable with pSLA2 telomeres than with pFRL1 telomeres in Streptomyces lividans.
Collapse
|
25
|
Wang J, Pettis GS. The tra locus of streptomycete plasmid pIJ101 mediates efficient transfer of a circular but not a linear version of the same replicon. MICROBIOLOGY-SGM 2010; 156:2723-2733. [PMID: 20522498 DOI: 10.1099/mic.0.036467-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Conjugal transfer of circular plasmids in Streptomyces involves a unique mechanism employing few plasmid-encoded loci and the transfer of double-stranded DNA by an as yet uncharacterized intercellular route. Efficient transfer of the circular streptomycete plasmid pIJ101 requires only two plasmid loci: the pIJ101 tra gene, and as a cis-acting function known as clt. Here, we compared the ability of the pIJ101 transfer apparatus to promote conjugal transfer of circular versus linear versions of the same replicon. While the pIJ101 tra locus readily transferred the circular form of the replicon, the linear version was transferred orders of magnitude less efficiently and all plasmids isolated from the transconjugants were circular, regardless of their original configuration in the donor. Additionally, relatively rare circularization of linear plasmids was detectable in the donor cells, which is consistent with the notion that this event was a prerequisite for transfer by TraB(pIJ101). Linear versions of this same replicon did transfer efficiently, in that configuration, from strains containing the conjugative linear plasmid SLP2. Our data indicate that functions necessary and sufficient for transfer of circular DNA were insufficient for transfer of a related linear DNA molecule. The results here suggest that the conjugation mechanisms of linear versus circular DNA in Streptomyces spp. are inherently different and/or that efficient transfer of linear DNA requires additional components.
Collapse
Affiliation(s)
- Jing Wang
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Gregg S Pettis
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| |
Collapse
|
26
|
Kolkenbrock S, Fetzner S. Identification and in vitro deoxynucleotidylation of the terminal protein of the linear plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a. FEMS Microbiol Lett 2010; 304:169-76. [PMID: 20141532 DOI: 10.1111/j.1574-6968.2010.01900.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a is a linear replicon, characterized by inverted terminal repeats and terminal proteins (TPs) covalently bound to its 5'-ends. Previous sequence analysis and predictions of possible secondary structures formed by telomeric 3'-overhangs indicated significant differences of the 'left' and 'right' telomere of pAL1, raising the question of whether each terminus is recognized by a specific protein. The genes pAL1.102 and pAL1.103, located close to a terminus, code for possible DNA-binding proteins; however, only the pORF102 protein encoded by pAL1.102 shows a weak similarity to known TPs of Streptomyces linear replicons. pORF102, purified from recombinant A. nitroguajacolicus Rü61a as a fusion with maltose-binding protein (MBP), was specifically associated with terminal pAL1 DNA, whereas MBP-pORF103 was devoid of DNA, suggesting that pORF102 represents the protein attached to both ends of the linear plasmid. In electrophoretic mobility shift assays, the MBP-pORF102 protein was not capable of specifically recognizing telomeric DNA sequences. Consistent with its proposed role as a protein primer in DNA synthesis, pORF102 was deoxynucleotidylated in vitro with dCMP, complementary to the 3'-ends (... GCAGG) of pAL1.
Collapse
Affiliation(s)
- Stephan Kolkenbrock
- Institute of Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany
| | | |
Collapse
|
27
|
Lin YR, Hahn MY, Roe JH, Huang TW, Tsai HH, Lin YF, Su TS, Chan YJ, Chen CW. Streptomyces telomeres contain a promoter. J Bacteriol 2009; 191:773-81. [PMID: 19060156 PMCID: PMC2632112 DOI: 10.1128/jb.01299-08] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 11/19/2008] [Indexed: 11/20/2022] Open
Abstract
Bidirectional replication of the linear chromosomes and plasmids of Streptomyces spp. results in single-strand overhangs at their 3' ends, which contain extensive complex palindromic sequences. The overhangs are believed to be patched by DNA synthesis primed by a terminal protein that remains covalently bound to the 5' ends of the telomeres. We discovered that in vitro a conserved 167-bp telomere DNA binds strongly to RNA polymerase holoenzyme and exhibits promoter activities stronger than those of an rRNA operon. In vivo, the telomere DNA exhibited promoter activity in both orientations on a circular plasmid in Streptomyces. The telomere promoter is also active on a linear plasmid during exponential growth. Such promoter activity in a telomere has not hitherto been observed in eukaryotic or prokaryotic replicons. Streptomyces telomere promoters may be involved in priming the terminal Okazaki fragment (during replication) replicative transfer (during conjugation), or expression of downstream genes (including a conserved ttrA helicase-like gene involved in conjugal transfer). Interestingly, the Streptomyces telomeres also function as a promoter in Escherichia coli and as a transcription enhancer in yeast.
Collapse
Affiliation(s)
- Yuh-ru Lin
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Zhang R, Xia H, Guo P, Qin Z. Variation in the replication loci of Streptomyces linear plasmids. FEMS Microbiol Lett 2008; 290:209-16. [PMID: 19054078 DOI: 10.1111/j.1574-6968.2008.01432.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Streptomyces linear plasmids start replication at centrally located loci, usually consisting of iterons and adjacent rep genes. Here, we identified four new replication loci from Streptomyces linear plasmids. A discontinuous locus, consisting of two genes and iterons separated by two nonessential genes, was required for replication of pRL2 in both linear and circular modes. A temperature-sensitive plasmid, pRL4, contained a replication locus, a noncoding sequence and a SAP1.35-like gene. A telomere-adjacent locus, another noncoding sequence and SAP1.1-like gene, was identified for replication of the large plasmid pFRL2. The replication locus of pSHK1 consisted of SCP1-rep-like genes and iterons. These results indicate an unexpected variety of components, positions and combinations of replication loci among Streptomyces linear plasmids.
Collapse
Affiliation(s)
- Ran Zhang
- Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | | | | | | |
Collapse
|
29
|
Kube M, Schneider B, Kuhl H, Dandekar T, Heitmann K, Migdoll AM, Reinhardt R, Seemüller E. The linear chromosome of the plant-pathogenic mycoplasma 'Candidatus Phytoplasma mali'. BMC Genomics 2008; 9:306. [PMID: 18582369 PMCID: PMC2459194 DOI: 10.1186/1471-2164-9-306] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 06/26/2008] [Indexed: 11/28/2022] Open
Abstract
Background Phytoplasmas are insect-transmitted, uncultivable bacterial plant pathogens that cause diseases in hundreds of economically important plants. They represent a monophyletic group within the class Mollicutes (trivial name mycoplasmas) and are characterized by a small genome with a low GC content, and the lack of a firm cell wall. All mycoplasmas, including strains of 'Candidatus (Ca.) Phytoplasma asteris' and 'Ca. P. australiense', examined so far have circular chromosomes, as is the case for almost all walled bacteria. Results Our work has shown that 'Ca. Phytoplasma mali', the causative agent of apple proliferation disease, has a linear chromosome. Linear chromosomes were also identified in the closely related provisional species 'Ca. P. pyri' and 'Ca. P. prunorum'. The chromosome of 'Ca. P. mali' strain AT is 601,943 bp in size and has a GC content of 21.4%. The chromosome is further characterized by large terminal inverted repeats and covalently closed hairpin ends. Analysis of the protein-coding genes revealed that glycolysis, the major energy-yielding pathway supposed for 'Ca. P. asteris', is incomplete in 'Ca. P. mali'. Due to the apparent lack of other metabolic pathways present in mycoplasmas, it is proposed that maltose and malate are utilized as carbon and energy sources. However, complete ATP-yielding pathways were not identified. 'Ca. P. mali' also differs from 'Ca. P. asteris' by a smaller genome, a lower GC content, a lower number of paralogous genes, fewer insertions of potential mobile DNA elements, and a strongly reduced number of ABC transporters for amino acids. In contrast, 'Ca. P. mali' has an extended set of genes for homologous recombination, excision repair and SOS response than 'Ca. P. asteris'. Conclusion The small linear chromosome with large terminal inverted repeats and covalently closed hairpin ends, the extremely low GC content and the limited metabolic capabilities reflect unique features of 'Ca. P. mali', not only within phytoplasmas, but all mycoplasmas. It is expected that the genome information obtained here will contribute to a better understanding of the reduced metabolism of phytoplasmas, their fastidious nutrition requirements that prevented axenic cultivation, and the mechanisms involved in pathogenicity.
Collapse
Affiliation(s)
- Michael Kube
- Max Planck Institute for Molecular Genetics, Ihnestr, 63, D-14195 Berlin, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Tsai HH, Huang CH, Lin AM, Chen CW. Terminal proteins of Streptomyces chromosome can target DNA into eukaryotic nuclei. Nucleic Acids Res 2008; 36:e62. [PMID: 18480119 PMCID: PMC2425503 DOI: 10.1093/nar/gkm1170] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Streptomyces species are highly abundant soil bacteria that possess linear chromosomes (and linear plasmids). The 5′ ends of these molecules are covalently bound by terminal proteins (TPs), that are important for integrity and replication of the telomeres. There are at least two types of TPs, both of which contain a DNA-binding domain and a classical eukaryotic nuclear localization signal (NLS). Here we show that the NLS motifs on these TPs are highly efficient in targeting the proteins along with covalently bound plasmid DNA into the nuclei of human cells. The TP-mediated nuclear targeting resembles the inter-kingdom gene transfer mediated by Ti plasmids of Agrobacterium tumefaciens, in which a piece of the Ti plasmid DNA is targeted to the plant nuclei by a covalently bound NLS-containing protein. The discovery of the nuclear localization functions of the Streptomyces TPs not only suggests possible inter-kingdom gene exchanges between Streptomyces and eukaryotes in soil but also provides a novel strategy for gene delivery in humans and other eukaryotes.
Collapse
Affiliation(s)
- Hsiu-Hui Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan
| | | | | | | |
Collapse
|
31
|
Characterization of replication and conjugation of Streptomyces circular plasmids pFP1 and pFP11 and their ability to propagate in linear mode with artificially attached telomeres. Appl Environ Microbiol 2008; 74:3368-76. [PMID: 18390681 DOI: 10.1128/aem.00402-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many Streptomyces species harbor circular plasmids (8 to 31 kb) as well as linear plasmids (12 to 1,700 kb). We report the characterization of two newly detected circular plasmids, pFP11 (35,139 bp) and pFP1 (39,360 bp). As on linear plasmids, their replication loci comprise repA genes and adjacent iterons, to which RepA proteins bind specifically in vitro. Plasmids containing the minimal iterons plus the repA locus of pFP11 were inherited extremely unstably; par and additional loci were required for stable inheritance. Surprisingly, plasmids containing replication loci from pFP11 or Streptomyces circular plasmid SCP2 but not from pFP1, SLP1, or pIJ101 propagated in a stable linear mode when the telomeres of a linear plasmid were attached. These results indicate bidirectional replication for pFP11 and SCP2. Both pFP11 and pFP1 contain, for plasmid transfer, a major functional traB gene (encoding a DNA translocase typical for Streptomyces plasmids) as well as, surprisingly, a putative traA gene (encoding a DNA nickase, characteristic of single-stranded DNA transfer of gram-negative plasmids), but this did not appear to be functional, at least in isolation.
Collapse
|
32
|
DNA polymerase I is not required for replication of linear chromosomes in streptomyces. J Bacteriol 2007; 190:755-8. [PMID: 17993519 DOI: 10.1128/jb.01335-07] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Both polA (encoding DNA polymerase I; Pol I) and a paralog were deleted from Streptomyces strains. Despite the UV sensitivity and slow growth caused by the DeltapolA mutation, the double mutant was viable. Thus, in contrast to a previous postulate, Pol I and its paralog are not essential for replication of Streptomyces chromosomes.
Collapse
|
33
|
Baker S, Holt K, Whitehead S, Goodhead I, Perkins T, Stocker B, Hardy J, Dougan G. A linear plasmid truncation induces unidirectional flagellar phase change in H:z66 positive Salmonella Typhi. Mol Microbiol 2007; 66:1207-18. [PMID: 17976161 PMCID: PMC2652032 DOI: 10.1111/j.1365-2958.2007.05995.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The process by which bacteria regulate flagellar expression is known as phase variation and in Salmonella enterica this process permits the expression of one of two flagellin genes, fliC or fljB, at any one time. Salmonella Typhi (S. Typhi) is normally not capable of phase variation of flagellar antigen expression as isolates only harbour the fliC gene (H:d) and lacks an equivalent fljB locus. However, some S. Typhi isolates, exclusively from Indonesia, harbour an fljB equivalent encoded on linear plasmid, pBSSB1 that drives the expression of a novel flagellin named H:z66. H:z66+S. Typhi isolates were stimulated to change flagellar phase and genetically analysed for the mechanism of variation. The phase change was demonstrated to be unidirectional, reverting to expression from the resident chromosomal fliC gene. DNA sequencing demonstrated that pBSSB1 linear DNA was still detectable but that these derivatives had undergone deletion and were lacking fljA(z66) (encoding a flagellar repressor) and fljB(z66). The deletion end-point was found to involve one of the plasmid termini and a palindromic repeat sequence within fljB(z66), distinct to that found at the terminus of pBSSB1. These data demonstrate that, like some Streptomyces linear elements, at least one of the terminal inverted repeats of pBSSB1 is non-essential, but that a palindromic repeat sequence may be necessary for replication.
Collapse
Affiliation(s)
- Stephen Baker
- The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK.
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Huang CH, Tsai HH, Tsay YG, Chien YN, Wang SL, Cheng MY, Ke CH, Chen CW. The telomere system of the Streptomyces linear plasmid SCP1 represents a novel class. Mol Microbiol 2007; 63:1710-8. [PMID: 17367390 DOI: 10.1111/j.1365-2958.2007.05616.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Linear plasmids and chromosomes of Streptomyces carry terminal proteins (TPs) covalently attached to the 5' ends of the DNA. Most known telomeres are conserved in primary sequence and in the potential secondary structures formed during replication. The TP that caps these telomeres is also highly conserved and its coding gene, tpg, is present in all Streptomyces chromosomes and some linear plasmids. Linear plasmid SCP1 contains atypical telomere sequences and no tpg homologue, and can replicate in the absence of tpg, suggesting that it carries a novel TP gene. To isolate the TP on the SCP1 telomeres, we constructed a multicopy mini-SCP1 plasmid. The TP capping the plasmid was isolated and subjected to tryptic digestion and mass spectrometric analysis, and the results indicated that the TP was encoded by an open reading frame (ORF), SCP1.127 (tpc), on SCP1. Of the two ORFs upstream of tpc, SCP1.125 (tac) but not SCP1.126 was essential for replication of mini-SCP1. The Tac-Tpc system of SCP1 represents a convergently evolved novel telomere-capping system of Streptomyces linear replicons.
Collapse
Affiliation(s)
- Chih-Hung Huang
- Institute of Biotechnology, National Taipei University of Technology, Taipei 106, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Baker S, Hardy J, Sanderson KE, Quail M, Goodhead I, Kingsley RA, Parkhill J, Stocker B, Dougan G. A novel linear plasmid mediates flagellar variation in Salmonella Typhi. PLoS Pathog 2007; 3:e59. [PMID: 17500588 PMCID: PMC1876496 DOI: 10.1371/journal.ppat.0030059] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Accepted: 03/06/2007] [Indexed: 11/20/2022] Open
Abstract
Unlike the majority of Salmonella enterica serovars, Salmonella Typhi (S. Typhi), the etiological agent of human typhoid, is monophasic. S. Typhi normally harbours only the phase 1 flagellin gene (fliC), which encodes the H:d antigen. However, some S. Typhi strains found in Indonesia express an additional flagellin antigen termed H:z66. Molecular analysis of H:z66+ S. Typhi revealed that the H:z66 flagellin structural gene (fljBz66) is encoded on a linear plasmid that we have named pBSSB1. The DNA sequence of pBSSB1 was determined to be just over 27 kbp, and was predicted to encode 33 coding sequences. To our knowledge, pBSSB1 is the first non-bacteriophage–related linear plasmid to be described in the Enterobacteriaceae. Flagella are whip-like structures found on the surface of bacterial cells that mediate swimming. Flagella contain a protein called flagellin, which is recognised as a danger signal by the immune system. Salmonella Typhi, the bacteria that causes typhoid fever, normally have flagella called H:d, but some strains only from Indonesia express distinct flagella, called H:z66. In this study we have located and sequenced the genes responsible for expressing these alternative flagella. Remarkably, these genes are located on a linear plasmid, an extra-chromosomal element that we have named pBSSB1. The significance of this finding is that linear plasmids are relatively common in bacterial species such as Streptomyces and Borrelia. However, such a linear element has never previously been described in enteric bacteria such as Escherichia coli and Salmonella. The identification of this novel linear plasmid in genetically tractable bacteria will facilitate future studies on the biology of linear plasmids and the pathogenicity of both flagella and Salmonella Typhi.
Collapse
Affiliation(s)
- Stephen Baker
- The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom.
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
The 8-9-Mb Streptomyces chromosome is linear, with a "core" containing essential genes and "arms" carrying conditionally adaptive genes that can sustain large deletions in the laboratory. Bidirectional chromosome replication from a central oriC is completed by "end-patching," primed from terminal proteins covalently bound to the free 5'-ends. Plasmid-mediated conjugation involves movement of double-stranded DNA by proteins resembling other bacterial motor proteins, probably via hyphal tip fusion, mediated by these transfer proteins. Circular plasmids probably transfer chromosomes by transient integration, but linear plasmids may lead the donor chromosome end-first into the recipient by noncovalent association of ends. Transfer of complete chromosomes may be the rule. The recipient mycelium is colonized by intramycelial spreading of plasmid copies, under the control of plasmid-borne "spread" genes. Chromosome partition into prespore compartments of the aerial mycelium is controlled in part by actin- and tubulin-like proteins, resembling MreB and FtsZ of other bacteria.
Collapse
Affiliation(s)
- David A Hopwood
- Department of Molecular Microbiology, John Innes Centre, Colney, Norwich, NR4 7UH, United Kingdom.
| |
Collapse
|
37
|
Zhang R, Yang Y, Fang P, Jiang C, Xu L, Zhu Y, Shen M, Xia H, Zhao J, Chen T, Qin Z. Diversity of telomere palindromic sequences and replication genes among Streptomyces linear plasmids. Appl Environ Microbiol 2006; 72:5728-33. [PMID: 16957187 PMCID: PMC1563600 DOI: 10.1128/aem.00707-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptomyces sp. linear plasmids and linear chromosomes usually contain conserved terminal palindromic sequences bound by the conserved telomeric proteins Tap and Tp, encoded by the tap and tpg genes, respectively, as well as plasmid loci required for DNA replication in circular mode when the telomeres are deleted. These consist of iterons and an adjacent rep gene. By using PCR, we found that 8 of 17 newly detected linear plasmids in Streptomyces strains lack typical telomeric tap and tpg sequences. Instead, two novel telomeres in plasmids pRL1 and pRL2 from the eight strains and one conserved telomere in pFRL1 from the other strains were identified, while multiple short palindromes were also found in the plasmids. The complete nucleotide sequence of pRL2 revealed a gene encoding a protein containing two domains, resembling Tap of Streptomyces and a helicase of Thiobacillus, and an adjacent gene encoding a protein similar to Tpg of Streptomyces and a portion of the telomere terminal protein pTP of adenoviruses. No typical iterons-rep loci were found in the three plasmids. These results indicate an unexpected diversity of telomere palindromic sequences and replication genes among Streptomyces linear plasmids.
Collapse
Affiliation(s)
- Ran Zhang
- Shanghai Institute of Plant Physiology, Shanghai Institutes of Biological Science, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Yang CC, Chen YH, Tsai HH, Huang CH, Huang TW, Chen CW. In vitro deoxynucleotidylation of the terminal protein of Streptomyces linear chromosomes. Appl Environ Microbiol 2006; 72:7959-61. [PMID: 17056688 PMCID: PMC1694218 DOI: 10.1128/aem.01857-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-stranded gaps at the 3' ends of Streptomyces linear replicons are patched by DNA synthesis primed by terminal proteins (TP) during replication. We devised an in vitro system that specifically incorporated dCMP, the first nucleotide at the 5' ends, onto a threonine residue of the TP of Streptomyces coelicolor.
Collapse
Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | | | | | | | | | | |
Collapse
|
39
|
Xu M, Zhu Y, Zhang R, Shen M, Jiang W, Zhao G, Qin Z. Characterization of the genetic components of Streptomyces lividans linear plasmid SLP2 for replication in circular and linear modes. J Bacteriol 2006; 188:6851-7. [PMID: 16980488 PMCID: PMC1595531 DOI: 10.1128/jb.00873-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleotide sequence of Streptomyces lividans linear plasmid SLP2 consists of 50,410 bp (C. H. Huang, C. Y. Chen, H. H. Tsai, C. Chen, Y. S. Lin, and C. W. Chen, Mol. Microbiol. 47:1563-1576, 2003). Here we report that the basic SLP2 locus for plasmid replication in circular mode resembles that of Streptomyces linear plasmids pSLA2 and SCP1 and comprises iterons(SLP2) and the adjacent rep(SLP2) gene. More efficient replication additionally required the 47-bp sequence between bp 581 and 628 upstream of the iterons. Replacement of either the iterons or the rep gene of SLP2 by the corresponding genes of pSLA2 or SCP1 still allows propagation in Streptomyces, although the transformation frequencies were 3 orders of magnitude lower than the original plasmids, suggesting that these plasmids share similar replication mechanisms. To replicate SLP2 in linear mode, additional SLP2 loci--either mtap(SLP2)/tpg(SLP2) or mtap(SLP2)/ilrA(SLP2)--were required. IlrA(SLP2) protein binds specifically to the iterons(SLP2) in vitro. Interactions were detected between these SLP2-borne replication proteins (Mtap(SLP2), Tpg(SLP2), and IlrA(SLP2)) and the telomeric replication proteins (TpgL, TapL, and TpgL) of the S. lividans chromosome, respectively, but the SLP2 proteins failed to interact. These results suggest that SLP2 recruits chromosomally encoded replication proteins for its telomere replication.
Collapse
Affiliation(s)
- Mingxuan Xu
- Shanghai Institute of Plant Physiology, Shanghai Institutes of Biological Sciences, The Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032 People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
40
|
Wu W, Leblanc SKD, Piktel J, Jensen SE, Roy KL. Prediction and functional analysis of the replication origin of the linear plasmid pSCL2 inStreptomyces clavuligerus. Can J Microbiol 2006; 52:293-300. [PMID: 16699579 DOI: 10.1139/w05-126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
pSCL2 (120 kb), one of the linear plasmids found in Streptomyces clavuligerus NRRL3585, was isolated and partially sequenced. Computational analysis of the central region of pSCL2 revealed the presence of two open reading frames that appear to encode proteins highly homologous to RepL1 and RepL2, replication proteins from pSLA2-L, the large linear plasmid in Streptomyces rochei. The S. clavuligerus open reading frames were designated repC1 and repC2, encoding the proteins RepC1 (150 amino acids) and RepC2 (102 amino acids), respectively. The RepC and RepL proteins have identical translation features and very similar predicted secondary and tertiary structures. Functional analysis confirmed that RepC1 is essential for replication initiation of pSCL2, whereas RepC2 is dispensable but may play a role in copy number control. The RepC and RepL proteins do not show similarity to any other bacterial plasmid replication proteins. Three regions of DNA sequence, Box 1 (1050–850 bp), Box 2 (723–606 bp), and Box 3 (224–168 bp), located upstream of repC1, were also shown to be essential or very important for replication of pSCL2.Key words: pSCL2, Streptomyces clavuligerus, replication origin.
Collapse
Affiliation(s)
- Wei Wu
- Department of Biological Sciences, CW 405 Biological Sciences Bldg., University of Alberta, Edmonton, Canada
| | | | | | | | | |
Collapse
|
41
|
Abstract
Chromosomes may be either circular or linear, the latter being prone to erosion caused by incomplete replication, degradation and inappropriate repair. Despite these problems, the linear form of DNA is frequently found in viruses, bacteria, eukaryotic nuclei and organelles. The high incidence of linear chromosomes and/or genomes evokes why and how they emerged in evolution. Here we suggest that the primordial terminal structures (telomeres) of linear chromosomes in eukaryotic nuclei were derived from selfish element(s), which caused the linearization of ancestral circular genome. The telomeres were then essential in solving the emerged problems. Molecular fossils of such elements were recently identified in phylogenetically distant genomes and were shown to generate terminal arrays of tandem repeats. These arrays might mediate the formation of higher order structures at chromosomal termini that stabilize the linear chromosomal form by fulfilling essential telomeric functions.
Collapse
Affiliation(s)
- Jozef Nosek
- Department of Biochemistry, Comenius University, Bratislava, Slovakia.
| | | | | |
Collapse
|
42
|
Overhage J, Sielker S, Homburg S, Parschat K, Fetzner S. Identification of large linear plasmids in Arthrobacter spp. encoding the degradation of quinaldine to anthranilate. MICROBIOLOGY-SGM 2005; 151:491-500. [PMID: 15699198 DOI: 10.1099/mic.0.27521-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Arthrobacter nitroguajacolicus Rü61a, which utilizes quinaldine as sole source of carbon and energy, was shown to contain a conjugative linear plasmid of approximately 110 kb, named pAL1. It exhibits similarities with other linear plasmids from Actinomycetales in that it has proteins covalently attached to its 5' ends. Southern hybridization with probes for the genes encoding quinaldine 4-oxidase and N-acetylanthranilate amidase indicated that pAL1 contains the gene cluster encoding the degradation of quinaldine to anthranilate. A mutant of strain Rü61a that had lost pAL1 indeed could not convert quinaldine, but was still able to grow on anthranilate. Conjugative transfer of pAL1 to the plasmid-less mutant of strain Rü61a and to Arthrobacter nicotinovorans DSM 420 (pAO1) occurred at frequencies of 5.4x10(-4) and 2.0x10(-4) per recipient, respectively, and conferred the ability to utilize quinaldine. Five other quinaldine-degrading Gram-positive strains were isolated from soil samples; 16S rDNA sequence analysis suggested the closest relationship to different Arthrobacter species. Except for strain K2-29, all isolates contained a pAL1-like linear plasmid carrying genes encoding quinaldine conversion. A 478 bp fragment that on pAL1 represents an intergenic region showed 100 % sequence identity in all isolates harbouring a pAL1-like plasmid, suggesting horizontal dissemination of the linear plasmid among the genus Arthrobacter.
Collapse
Affiliation(s)
- Jörg Overhage
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, D-48149 Münster, Germany
| | - Sonja Sielker
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, D-48149 Münster, Germany
| | - Stefan Homburg
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, D-48149 Münster, Germany
| | - Katja Parschat
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, D-48149 Münster, Germany
| | - Susanne Fetzner
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, D-48149 Münster, Germany
| |
Collapse
|
43
|
Abstract
Recent advances in DNA-sequencing technologies have made available an enormous resource of data for the study of bacterial genomes. The broad sample of complete genomes currently available allows us to look at variation in the gross features and characteristics of genomes while the detail of the sequences reveal some of the mechanisms by which these genomes evolve. This review aims to describe bacterial genome structures according to current knowledge and proposed hypotheses. We also describe examples where mechanisms of genome evolution have acted in the adaptation of bacterial species to particular niches.
Collapse
Affiliation(s)
- Stephen D Bentley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire CB10 1SA, UK.
| | | |
Collapse
|
44
|
Warren R, Hsiao WWL, Kudo H, Myhre M, Dosanjh M, Petrescu A, Kobayashi H, Shimizu S, Miyauchi K, Masai E, Yang G, Stott JM, Schein JE, Shin H, Khattra J, Smailus D, Butterfield YS, Siddiqui A, Holt R, Marra MA, Jones SJM, Mohn WW, Brinkman FSL, Fukuda M, Davies J, Eltis LD. Functional characterization of a catabolic plasmid from polychlorinated- biphenyl-degrading Rhodococcus sp. strain RHA1. J Bacteriol 2004; 186:7783-95. [PMID: 15516593 PMCID: PMC524921 DOI: 10.1128/jb.186.22.7783-7795.2004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhodococcus sp. strain RHA1, a potent polychlorinated-biphenyl (PCB)-degrading strain, contains three linear plasmids ranging in size from 330 to 1,100 kb. As part of a genome sequencing project, we report here the complete sequence and characterization of the smallest and least-well-characterized of the RHA1 plasmids, pRHL3. The plasmid is an actinomycete invertron, containing large terminal inverted repeats with a tightly associated protein and a predicted open reading frame (ORF) that is similar to that of a mycobacterial rep gene. The pRHL3 plasmid has 300 putative genes, almost 21% of which are predicted to have a catabolic function. Most of these are organized into three clusters. One of the catabolic clusters was predicted to include limonene degradation genes. Consistent with this prediction, RHA1 grew on limonene, carveol, or carvone as the sole carbon source. The plasmid carries three cytochrome P450-encoding (CYP) genes, a finding consistent with the high number of CYP genes found in other actinomycetes. Two of the CYP genes appear to belong to novel families; the third belongs to CYP family 116 but appears to belong to a novel class based on the predicted domain structure of its reductase. Analyses indicate that pRHL3 also contains four putative "genomic islands" (likely to have been acquired by horizontal transfer), insertion sequence elements, 19 transposase genes, and a duplication that spans two ORFs. One of the genomic islands appears to encode resistance to heavy metals. The plasmid does not appear to contain any housekeeping genes. However, each of the three catabolic clusters contains related genes that appear to be involved in glucose metabolism.
Collapse
|
45
|
Lue NF, Jiang S. Reverse transcriptase at bacterial telomeres. Proc Natl Acad Sci U S A 2004; 101:14307-8. [PMID: 15454610 PMCID: PMC521969 DOI: 10.1073/pnas.0406018101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Neal F Lue
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
| | | |
Collapse
|
46
|
Bao K, Cohen SN. Reverse transcriptase activity innate to DNA polymerase I and DNA topoisomerase I proteins of Streptomyces telomere complex. Proc Natl Acad Sci U S A 2004; 101:14361-6. [PMID: 15353591 PMCID: PMC521936 DOI: 10.1073/pnas.0404386101] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Replication of Streptomyces linear chromosomes and plasmids proceeds bidirectionally from a central origin, leaving recessed 5' termini that are extended by a telomere binding complex. This complex contains both a telomere-protecting terminal protein (Tpg) and a telomere-associated protein that interacts with Tpg and the DNA ends of linear Streptomyces replicons. By using histidine-tagged telomere-associated protein (Tap) as a scaffold, we identified DNA polymerase (PolA) and topoisomerase I (TopA) proteins as other components of the Streptomyces telomere complex. Biochemical characterization of these proteins indicated that both PolA and TopA exhibit highly efficient reverse transcriptase (RT) activity in addition to their predicted functions. Although RT activity innate to other DNA-dependent DNA polymerases has been observed previously, its occurrence in a topoisomerase is unprecedented. Deletion mapping and sequence analysis showed that the RT activity of Streptomcyces TopA resides in a peptide region containing motifs that are absent from most bacterial topoisomerases but are highly conserved in a novel subfamily of eubacterial topoisomerases found largely in Actinobacteria. Within one of these motifs, and essential to the RT function of Streptomyces TopA, is an Asp-Asp doublet sequence required also for the RT activities of human immunodeficiency virus and eukaryotic cell telomerases.
Collapse
Affiliation(s)
- Kai Bao
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305-5120, USA
| | | |
Collapse
|
47
|
Hosted TJ, Wang T, Horan AC. Characterization of the Streptomyces lavendulae IMRU 3455 linear plasmid pSLV45. Microbiology (Reading) 2004; 150:1819-1827. [PMID: 15184568 DOI: 10.1099/mic.0.26994-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Streptomyces lavendulae IMRU 3455 contains two large linear plasmids designated pSLV45 (45 kb) and pSLV195 (195 kb). A cosmid, pSPRX604, containing 42 kb from pSLV45 was cloned and sequenced. pSLV45 was tagged with a hygromycin-resistance marker by homologous recombination to generate the derivatives pSLV45.680 and pSLV45.681. An apramycin-resistance marker was introduced into S. lavendulae IMRU 467 using the pSPR910 integration vector to yield the recipient strain SPW910. The self-transmissible nature of pSLV45 was determined by transfer of pSLV45.680 and pSLV45.681 from the donor strains SPW680 and SPW681 into the recipient strain SPW910. Southern analysis indicated the presence of hygromycin- and pSLV45-hybridizing sequences within SPW910 exconjugants. PFGE analysis confirmed pSLV45.680 and pSLV45.681 were transferred intact and formed freely replicating linear plasmids. Sequence analysis of pSPRX604 revealed genes predicted to be involved in plasmid transfer, partitioning and regulation. The transfer of the linear plasmid pSLV45 from S. lavendulae IMRU 3455 into S. lavendulae IMRU 467 may allow the development of pSLV45 as an actinomycete-to-actinomycete conjugative shuttle vector.
Collapse
Affiliation(s)
- Thomas J Hosted
- New Lead Discovery, Schering Plough Research Institute, 2015 Galloping Hill Road, K15-C321-MS3600, Kenilworth, NJ 07033, USA
| | - Tim Wang
- New Lead Discovery, Schering Plough Research Institute, 2015 Galloping Hill Road, K15-C321-MS3600, Kenilworth, NJ 07033, USA
| | - Ann C Horan
- New Lead Discovery, Schering Plough Research Institute, 2015 Galloping Hill Road, K15-C321-MS3600, Kenilworth, NJ 07033, USA
| |
Collapse
|
48
|
Qin Z, Shen M, Cohen SN. Identification and characterization of a pSLA2 plasmid locus required for linear DNA replication and circular plasmid stable inheritance in Streptomyces lividans. J Bacteriol 2003; 185:6575-82. [PMID: 14594830 PMCID: PMC262113 DOI: 10.1128/jb.185.22.6575-6582.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptomyces linear plasmids and linear chromosomes can replicate also in a circular form when their telomeres are deleted. The 17-kb linear plasmid pSLA2 has been a useful model in studies of such replicons. Here we report that the minimal origin initiating replication of pSLA2-derived plasmids as circular molecules cannot propagate these plasmids in a linear mode unless they also contain a novel plasmid-encoded locus, here named rlrA (required for linear replication). In contrast with the need for rlrA to accomplish replication of telomere-containing linear plasmids, expression of rlrA, which encodes two LuxR family regulatory domains, interferes with the establishment of pSLA2 in circular form in Streptomyces lividans transformants. The additional presence of an adjacent divergently transcribed locus, rorA (rlrA override), which strongly resembles the kor (kil override) transcription control genes identified previously on Streptomyces plasmids, reversed the detrimental effects of rlrA on plasmid establishment and additionally stabilized circular plasmid inheritance by spores during the S. lividans life cycle. While the effects of the rlrA/rorA locus of pSLA2 were seen also on linear plasmids derived from the unrelated SLP2 replicon, they did not extend to plasmids whose replication was initiated at a cloned chromosomal origin. Our results establish the existence of, and provide the initial description of, a novel plasmid-borne regulatory system that differentially affects the propagation of linear and circular plasmids in Streptomyces.
Collapse
Affiliation(s)
- Zhongjun Qin
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305-5120, USA
| | | | | |
Collapse
|
49
|
Paradkar A, Trefzer A, Chakraburtty R, Stassi D. Streptomyces genetics: a genomic perspective. Crit Rev Biotechnol 2003; 23:1-27. [PMID: 12693442 DOI: 10.1080/713609296] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Streptomycetes are gram-positive, soil-inhabiting bacteria of the order Actinomycetales. These organisms exhibit an unusual, developmentally complex life cycle and produce many economically important secondary metabolites, such as antibiotics, immunosuppressants, insecticides, and anti-tumor agents. Streptomyces species have been the subject of genetic investigation for over 50 years, with many studies focusing on the developmental cycle and the production of secondary metabolites. This information provides a solid foundation for the application of structural and functional genomics to the actinomycetes. The complete DNA sequence of the model organism, Streptomyces coelicolor M145, has been published recently, with others expected to follow soon. As more genomic sequences become available, the rational genetic manipulation of these organisms to elucidate metabolic and regulatory networks, to increase the production of commercially important compounds, and to create novel secondary metabolites will be greatly facilitated. This review presents the current state of the field of genomics as it is being applied to the actinomycetes.
Collapse
Affiliation(s)
- Ashish Paradkar
- Small Molecule Discovery, Diversa Corporation, 4955 Directors Place, San Diego, CA 92121, USA
| | | | | | | |
Collapse
|
50
|
Mochizuki S, Hiratsu K, Suwa M, Ishii T, Sugino F, Yamada K, Kinashi H. The large linear plasmid pSLA2-L of Streptomyces rochei has an unusually condensed gene organization for secondary metabolism. Mol Microbiol 2003; 48:1501-10. [PMID: 12791134 DOI: 10.1046/j.1365-2958.2003.03523.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The complete nucleotide sequence of the large linear plasmid pSLA2-L in Streptomyces rochei strain 7434AN4 has been determined. pSLA2-L was found to be 210 614 bp long with a GC content of 72.8% and carries 143 open reading frames. It is especially noteworthy that three-quarters of the pSLA2-L DNA is occupied by secondary metabolism-related genes, namely two type I polyketide synthase (PKS) gene clusters for lankacidin and lankamycin, a mithramycin synthase-like type II PKS gene cluster, a carotenoid biosynthetic gene cluster and many regulatory genes. In particular, the lankacidin PKS is unique, because it may be a mixture of modular- and iterative-type PKSs and carries a fusion protein of non-ribosomal peptide synthetase and PKS. It is also interesting that all the homologues of the afsA, arpA, adpA and strR genes in the A-factor regulatory cascade in Streptomyces griseus were found on pSLA2-L, and disruption of the afsA homologue caused non-production of both lankacidin and lankamycin. These results, together with the finding of three possible replication origins at 50-63 kb from the right end, suggest that the present form of pSLA2-L might have been generated by a series of insertions of the biosynthetic gene clusters into the left side of the original plasmid.
Collapse
Affiliation(s)
- Susumu Mochizuki
- Department of Molecular Biotechnology, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | | | | | | | | | | | | |
Collapse
|