The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection.
Lsr2 is a small DNA-binding protein present in mycobacteria and related actinobacteria that regulates gene expression and influences the organization of bacterial chromatin. Lsr2 is a dimer that binds to AT-rich regions of chromosomal DNA and physically protects DNA from damage by reactive oxygen in...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2012-01-01
|
| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3374832?pdf=render |
| _version_ | 1818510530155905024 |
|---|---|
| author | Emma L Summers Kathrin Meindl Isabel Usón Alok K Mitra Mazdak Radjainia Roberto Colangeli David Alland Vickery L Arcus |
| author_facet | Emma L Summers Kathrin Meindl Isabel Usón Alok K Mitra Mazdak Radjainia Roberto Colangeli David Alland Vickery L Arcus |
| author_sort | Emma L Summers |
| collection | DOAJ |
| description | Lsr2 is a small DNA-binding protein present in mycobacteria and related actinobacteria that regulates gene expression and influences the organization of bacterial chromatin. Lsr2 is a dimer that binds to AT-rich regions of chromosomal DNA and physically protects DNA from damage by reactive oxygen intermediates (ROI). A recent structure of the C-terminal DNA-binding domain of Lsr2 provides a rationale for its interaction with the minor groove of DNA, its preference for AT-rich tracts, and its similarity to other bacterial nucleoid-associated DNA-binding domains. In contrast, the details of Lsr2 dimerization (and oligomerization) via its N-terminal domain, and the mechanism of Lsr2-mediated chromosomal cross-linking and protection is unknown. We have solved the structure of the N-terminal domain of Lsr2 (N-Lsr2) at 1.73 Å resolution using crystallographic ab initio approaches. The structure shows an intimate dimer of two ß-ß-a motifs with no close homologues in the structural databases. The organization of individual N-Lsr2 dimers in the crystal also reveals a mechanism for oligomerization. Proteolytic removal of three N-terminal residues from Lsr2 results in the formation of an anti-parallel β-sheet between neighboring molecules and the formation of linear chains of N-Lsr2. Oligomerization can be artificially induced using low concentrations of trypsin and the arrangement of N-Lsr2 into long chains is observed in both monoclinic and hexagonal crystallographic space groups. In solution, oligomerization of N-Lsr2 is also observed following treatment with trypsin. A change in chromosomal topology after the addition of trypsin to full-length Lsr2-DNA complexes and protection of DNA towards DNAse digestion can be observed using electron microscopy and electrophoresis. These results suggest a mechanism for oligomerization of Lsr2 via protease-activation leading to chromosome compaction and protection, and concomitant down-regulation of large numbers of genes. This mechanism is likely to be relevant under conditions of stress where cellular proteases are known to be upregulated. |
| first_indexed | 2024-12-10T23:21:14Z |
| format | Article |
| id | doaj.art-b8bce0e5ae9a46aeb8db490a5a85e151 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-10T23:21:14Z |
| publishDate | 2012-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-b8bce0e5ae9a46aeb8db490a5a85e1512022-12-22T01:29:42ZengPublic Library of Science (PLoS)PLoS ONE1932-62032012-01-0176e3854210.1371/journal.pone.0038542The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection.Emma L SummersKathrin MeindlIsabel UsónAlok K MitraMazdak RadjainiaRoberto ColangeliDavid AllandVickery L ArcusLsr2 is a small DNA-binding protein present in mycobacteria and related actinobacteria that regulates gene expression and influences the organization of bacterial chromatin. Lsr2 is a dimer that binds to AT-rich regions of chromosomal DNA and physically protects DNA from damage by reactive oxygen intermediates (ROI). A recent structure of the C-terminal DNA-binding domain of Lsr2 provides a rationale for its interaction with the minor groove of DNA, its preference for AT-rich tracts, and its similarity to other bacterial nucleoid-associated DNA-binding domains. In contrast, the details of Lsr2 dimerization (and oligomerization) via its N-terminal domain, and the mechanism of Lsr2-mediated chromosomal cross-linking and protection is unknown. We have solved the structure of the N-terminal domain of Lsr2 (N-Lsr2) at 1.73 Å resolution using crystallographic ab initio approaches. The structure shows an intimate dimer of two ß-ß-a motifs with no close homologues in the structural databases. The organization of individual N-Lsr2 dimers in the crystal also reveals a mechanism for oligomerization. Proteolytic removal of three N-terminal residues from Lsr2 results in the formation of an anti-parallel β-sheet between neighboring molecules and the formation of linear chains of N-Lsr2. Oligomerization can be artificially induced using low concentrations of trypsin and the arrangement of N-Lsr2 into long chains is observed in both monoclinic and hexagonal crystallographic space groups. In solution, oligomerization of N-Lsr2 is also observed following treatment with trypsin. A change in chromosomal topology after the addition of trypsin to full-length Lsr2-DNA complexes and protection of DNA towards DNAse digestion can be observed using electron microscopy and electrophoresis. These results suggest a mechanism for oligomerization of Lsr2 via protease-activation leading to chromosome compaction and protection, and concomitant down-regulation of large numbers of genes. This mechanism is likely to be relevant under conditions of stress where cellular proteases are known to be upregulated.http://europepmc.org/articles/PMC3374832?pdf=render |
| spellingShingle | Emma L Summers Kathrin Meindl Isabel Usón Alok K Mitra Mazdak Radjainia Roberto Colangeli David Alland Vickery L Arcus The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. PLoS ONE |
| title | The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. |
| title_full | The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. |
| title_fullStr | The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. |
| title_full_unstemmed | The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. |
| title_short | The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. |
| title_sort | structure of the oligomerization domain of lsr2 from mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection |
| url | http://europepmc.org/articles/PMC3374832?pdf=render |
| work_keys_str_mv | AT emmalsummers thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT kathrinmeindl thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT isabeluson thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT alokkmitra thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT mazdakradjainia thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT robertocolangeli thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT davidalland thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT vickerylarcus thestructureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT emmalsummers structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT kathrinmeindl structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT isabeluson structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT alokkmitra structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT mazdakradjainia structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT robertocolangeli structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT davidalland structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection AT vickerylarcus structureoftheoligomerizationdomainoflsr2frommycobacteriumtuberculosisrevealsamechanismforchromosomeorganizationandprotection |