Related Experiment Video

Updated: May 11, 2026

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues
12:07

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues

Published on: November 22, 2014

The endosymbiont Amoebophilus asiaticus encodes an S-adenosylmethionine carrier that compensates for its missing

Ilka Haferkamp1, Thomas Penz, Melanie Geier

  • 1Zelluläre Physiologie/Membrantransport, Technische Universität Kaiserslautern, Kaiserslautern, Germany.

Journal of Bacteriology
|May 14, 2013
PubMed

Insights

Certain bacteria, like Amoebophilus asiaticus, lack S-adenosylmethionine (SAM) synthesis and use a proton-driven transporter to import SAM, compensating for their lost methylation cycle.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • S-adenosylmethionine (SAM) is essential for all organisms as a methyl donor.
  • Some parasitic bacteria and amoeba symbionts cannot synthesize SAM and must import it.
  • Amoebophilus asiaticus, an amoeba symbiont, was found to lack SAM synthesis capabilities.

Purpose of the Study:

  • To identify and functionally characterize the SAM transporter in A. asiaticus.
  • To elucidate the mechanism of SAM transport in A. asiaticus.
  • To understand the prevalence and evolutionary significance of SAM transport in bacteria.

Main Methods:

  • Genome analysis to identify a putative SAM transporter gene in A. asiaticus.
  • Heterologous expression and functional characterization of the transporter in Escherichia coli.
  • SAM and S-adenosylhomocysteine (SAH) import assays.
  • Membrane potential dependency studies and proton-driven antiport mechanism investigation.

Main Results:

  • A. asiaticus encodes a specific SAM transporter.
  • The transporter mediates the uptake of SAM and SAH, functioning as a SAM/SAH antiporter.
  • Transport is driven by a proton gradient, indicating a proton-driven antiport mechanism.
  • SAM transport is crucial for compensating the missing methylation cycle in A. asiaticus.

Conclusions:

  • The identified SAM transporter in A. asiaticus is vital for its survival by enabling SAM uptake.
  • SAM/SAH antiport mechanism is a key strategy for organisms lacking SAM synthesis.
  • The presence of SAM transporters in Bacteroidetes expands the known phyla harboring this mechanism, alongside Proteobacteria and Chlamydiae.

More Related Videos

In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 (Ehmeth) Enzyme12:36

In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 (Ehmeth) Enzyme

Published on: October 19, 2010

Profiling of Methyltransferases and Other S-adenosyl-L-homocysteine-binding Proteins by Capture Compound Mass Spectrometry (CCMS)17:12

Profiling of Methyltransferases and Other S-adenosyl-L-homocysteine-binding Proteins by Capture Compound Mass Spectrometry (CCMS)

Published on: December 20, 2010

Related Concept Videos

Sulfur Assimilation01:20

Sulfur Assimilation

Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
Mismatch Repair01:20

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Mismatch Repair01:36

Mismatch Repair

Overview
Phase II Reactions: Methylation Reactions01:17

Phase II Reactions: Methylation Reactions

Methylation is a phase II biotransformation process involving the attachment of a methyl group to a substrate. Enzymes known as methyltransferases orchestrate this reaction.
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
Amino Acid Biosynthetic Pathways01:29

Amino Acid Biosynthetic Pathways

Amino acid biosynthesis is essential for cell growth, protein synthesis, and metabolic regulation. Cells generate essential and non-essential amino acids from metabolic intermediates to sustain vital biological functions. These intermediates originate from key metabolic pathways: glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Important precursors include α-ketoglutarate, pyruvate, oxaloacetate, phosphoenolpyruvate, and erythrose-4-phosphate, which provide...
RNA Editing02:23

RNA Editing

RNA editing is a post-transcriptional modification where a precursor mRNA (pre-mRNA) nucleotide sequence is changed by base insertion, deletion, or modification. The extent of RNA editing varies from a few hundred bases, in mitochondrial DNA of trypanosomes, to a just single base, in nuclear genes of mammals. Even a single base change in the pre-mRNA can convert a codon for one amino acid into the codon for another amino acid or a stop codon. This type of re-coding can significantly affect the...