Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:5.99.1.2 (
topoisomerase
)
9,166
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
DNA methylation plays a crucial role for gene regulation among eukaryotes, but its regulatory function is less documented in bacteria. In the cyanobacterium
Synechocystis
sp.
PCC
6803 five DNA methyltransferases have been identified. Among them, M.Ssp6803II is responsible for the specific methylation of the first cytosine in the frequently occurring motif GGCC, leading to N4-methylcytosine (GG
m4
CC). The mutation of the corresponding gene
sll0729
led to lowered chlorophyll/phycocyanin ratio and slower growth. Transcriptomics only showed altered expression of
sll0470
and
sll1526
, two genes encoding hypothetical proteins. Moreover, prolonged cultivation revealed instability of the initially obtained phenotype. Colonies with normal pigmentation and wild-type-like growth regularly appeared on agar plates. These colonies represent suppressor mutants, because the
sll0729
gene was still completely inactivated and the GGCC sites remained unmethylated. The suppressor strains showed smaller cell size, lowered DNA content per cell, and decreased tolerance against UV compared to wild type. Promoter assays revealed that the transcription of the
sll0470
gene was still stimulated in the suppressor clones. Proteomics identified decreased levels of
DNA topoisomerase
4 subunit A in suppressor cells. Collectively, these results indicate that GG
m4
CC methylation is involved in the regulation of gene expression, in the fine-tuning of DNA replication, and DNA repair mechanisms.
...
PMID:Cytosine N4-Methylation via M.Ssp6803II Is Involved in the Regulation of Transcription, Fine- Tuning of DNA Replication and DNA Repair in the Cyanobacterium
Synechocystis
sp. PCC 6803. 3123 31
