PMID:24449750

Citation	Lebreton, A, Job, V, Ragon, M, Le Monnier, A, Dessen, A, Cossart, P and Bierne, H (2014) Structural basis for the inhibition of the chromatin repressor BAHD1 by the bacterial nucleomodulin LntA. MBio 5:e00775-13
Abstract	The nucleus has emerged as a key target for nucleomodulins, a family of effectors produced by bacterial pathogens to control host transcription or other nuclear processes. The virulence factor LntA from Listeria monocytogenes stimulates interferon responses during infection by inhibiting BAHD1, a nuclear protein involved in gene silencing by promoting heterochromatin formation. So far, whether the interaction between LntA and BAHD1 is direct and sufficient for inhibiting BAHD1 activity is unknown. Here, we functionally characterized the molecular interface between the two proteins in vitro and in transfected or infected human cells. Based on the known tridimensional structure of LntA, we identified a dilysine motif (K180/K181) in the elbow region of LntA and a central proline-rich region in BAHD1 as crucial for the direct LntA-BAHD1 interaction. To better understand the role played by the dilysine motif in the functionality of LntA, we solved the crystal structure of a K180D/K181D mutant to a 2.2-Å resolution. This mutant highlights a drastic redistribution of surface charges in the vicinity of a groove, which likely plays a role in nucleomodulin target recognition. Mutation of the strategic dilysine motif also abolished the recruitment of LntA to BAHD1-associated nuclear foci and impaired the LntA-mediated stimulation of interferon responses upon infection. Last, the strict conservation of residues K180 and K181 in LntA sequences from 188 L. monocytogenes strains of different serotypes and origins further supports their functional importance. Together, these results provide structural and functional details about the mechanism of inhibition of an epigenetic factor by a bacterial nucleomodulin.
Links	PubMed PMC3903274 Online version:10.1128/mBio.00775-13
Keywords	Cell Line; Chromosomal Proteins, Non-Histone/antagonists & inhibitors; Crystallography, X-Ray; DNA Mutational Analysis; Humans; Interferons/secretion; Listeria monocytogenes/metabolism; Models, Molecular; Mutant Proteins/chemistry; Mutant Proteins/genetics; Mutant Proteins/metabolism; Protein Binding; Protein Conformation; Protein Interaction Mapping; Virulence Factors/chemistry; Virulence Factors/genetics; Virulence Factors/metabolism
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LISMO:LNTA		GO:0009405: pathogenesis	ECO:0000314:		P		Fig 1.	complete CACAO 11187
LISMO:LNTA		GO:0042025: host cell nucleus	ECO:0000314:		C		Figure S3A - LntA-V5 colocalizes with DAPI, a protein known to localize on the nucleus.	complete CACAO 11188

References

See Help:References for how to manage references in GONUTS.