Related Experiment Video
Updated: Aug 5, 2026
14:58
High-Throughput Transcriptome Analysis for Investigating Host-Pathogen Interactions
Published on: March 5, 2022
Histone modification crosstalk between host and pathogen
Biorxiv : the Preprint Server for Biology
|July 29, 2026
Summary
Bacterial pathogens use effector proteins to alter host cells. This study reveals that the Legionella effector RomA
Area of Science:
- Molecular Biology
- Epigenetics
- Microbiology
- Host-Pathogen Interactions
Background:
- Bacterial pathogens secrete effector proteins to manipulate host cell functions, including chromatin modification.
- The impact of the host epigenetic landscape on bacterial effector activity is largely unknown.
- RomA from Legionella pneumophila is a histone methyltransferase targeting H3K14 to suppress host immunity.
Purpose of the Study:
- To investigate how pre-existing host histone modifications regulate the activity of the bacterial effector RomA.
- To elucidate the mechanisms by which host epigenetics constrain bacterial effector function.
Main Methods:
- Biochemical assays to assess RomA activity in the presence of various histone modifications.
- Cryo-electron microscopy (cryo-EM) to determine the structural basis of RomA-nucleosome interactions.
- Analysis of cis- and trans-histone crosstalk mechanisms influencing RomA function.
Main Results:
- RomA activity is inhibited by specific histone post-translational modifications (PTMs) associated with active transcription, such as H3K4 trimethylation and acetylation, and H4K12 mono-methylation.
- RomA selectively binds and methylates unmodified histone H3 tails.
- Both cis- (on the same H3 tail) and trans-histone (across nucleosomes) crosstalk mechanisms regulate RomA activity, mirroring eukaryotic chromatin regulation.
- RomA interacts with histone tails rather than the nucleosome acidic patch.
Conclusions:
- The host epigenetic landscape actively constrains bacterial effector function, representing a novel layer of host-pathogen interaction.
- Legionella effector RomA exhibits selectivity based on the host's epigenetic state, utilizing mechanisms previously observed only in eukaryotic systems.
- This study reveals an unexpected form of host-pathogen crosstalk where bacterial effector activity is modulated by host epigenetic modifications.
Related Concept Videos
02:25Spreading of Chromatin Modifications
The histone proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are methylation, acetylation, phosphorylation, and ubiquitination of lysine amino acids in the histone H3 tail region. These histone modifications have specific meaning for the cell. Hence, they are called "histone code". The protein complex involved in histone modification is termed as "reader-writer" complex.
Writers
The writer is an enzyme that can...
Writers
The writer is an enzyme that can...
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
01:25Colonisation of Pathogens
Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
01:22Microbial Interactions: Parasitism
Parasitism is a form of microbial interaction in which parasitic microbes exploit a host organism for nutrients and shelter, often at the host's expense. Unlike mutualistic relationships, where both organisms benefit, parasitism benefits only the parasite and harms the host.Classification of ParasitesMicrobial parasites are broadly classified based on their location relative to the host.Ectoparasites remain on the host’s surface, such as the skin or outer tissues, drawing nutrients...
01:12The Nucleosome Core Particle
Nucleosomes are the DNA-histone complex, where the DNA strand is wound around the histone core. The histone core is an octamer containing two copies of H2A, H2B, H3, and H4 histone proteins.
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...
Nucleosomes, paradoxically, perform two opposite functions simultaneously. On the one hand, their primary aim is to protect the delicate DNA strands from physical damage and help achieve a higher compaction ratio. On the other hand, they must allow polymerase enzymes to access histone-bound DNA during...