| Structural highlights
Function
[LSR2_MYCTU] DNA-bridging protein that has both architectural and regulatory roles. Influences the organization of chromatin and gene expression by binding non-specifically to DNA, with a preference for AT-rich sequences, and bridging distant DNA segments. Represses expression of multiple genes involved in a broad range of cellular processes, including major virulence factors or antibiotic-induced genes, such as iniBAC or efpA. May coordinate global gene regulation and virulence. Also protects mycobacteria against reactive oxygen intermediates during macrophage infection by acting as a physical barrier to DNA degradation.[1] [2] [3] [4]
Publication Abstract from PubMed
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 A 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 beta-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.
The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection.,Summers EL, Meindl K, Uson I, Mitra AK, Radjainia M, Colangeli R, Alland D, Arcus VL PLoS One. 2012;7(6):e38542. doi: 10.1371/journal.pone.0038542. Epub 2012 Jun 13. PMID:22719899[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Colangeli R, Helb D, Vilcheze C, Hazbon MH, Lee CG, Safi H, Sayers B, Sardone I, Jones MB, Fleischmann RD, Peterson SN, Jacobs WR Jr, Alland D. Transcriptional regulation of multi-drug tolerance and antibiotic-induced responses by the histone-like protein Lsr2 in M. tuberculosis. PLoS Pathog. 2007 Jun;3(6):e87. PMID:17590082 doi:http://dx.doi.org/10.1371/journal.ppat.0030087
- ↑ Chen JM, Ren H, Shaw JE, Wang YJ, Li M, Leung AS, Tran V, Berbenetz NM, Kocincova D, Yip CM, Reyrat JM, Liu J. Lsr2 of Mycobacterium tuberculosis is a DNA-bridging protein. Nucleic Acids Res. 2008 Apr;36(7):2123-35. doi: 10.1093/nar/gkm1162. Epub 2008, Jan 10. PMID:18187505 doi:http://dx.doi.org/10.1093/nar/gkm1162
- ↑ Colangeli R, Haq A, Arcus VL, Summers E, Magliozzo RS, McBride A, Mitra AK, Radjainia M, Khajo A, Jacobs WR Jr, Salgame P, Alland D. The multifunctional histone-like protein Lsr2 protects mycobacteria against reactive oxygen intermediates. Proc Natl Acad Sci U S A. 2009 Mar 17;106(11):4414-8. doi:, 10.1073/pnas.0810126106. Epub 2009 Feb 23. PMID:19237572 doi:http://dx.doi.org/10.1073/pnas.0810126106
- ↑ Gordon BR, Li Y, Wang L, Sintsova A, van Bakel H, Tian S, Navarre WW, Xia B, Liu J. Lsr2 is a nucleoid-associated protein that targets AT-rich sequences and virulence genes in Mycobacterium tuberculosis. Proc Natl Acad Sci U S A. 2010 Jan 20. PMID:20133735
- ↑ Summers EL, Meindl K, Uson I, Mitra AK, Radjainia M, Colangeli R, Alland D, Arcus VL. The structure of the oligomerization domain of Lsr2 from Mycobacterium tuberculosis reveals a mechanism for chromosome organization and protection. PLoS One. 2012;7(6):e38542. doi: 10.1371/journal.pone.0038542. Epub 2012 Jun 13. PMID:22719899 doi:http://dx.doi.org/10.1371/journal.pone.0038542
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