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[Structural organization of the bacterial nucleoid using endonucleolysis]
Biokhimiia (Moscow, Russia)
|October 1, 1980
Summary
Bacterial deoxyribonucleoprotein (bDNP) fragmentation by endonucleases reveals an orderly DNA structure and protein composition similar to histones in gram-negative bacteria. This suggests genome-wide functional state variations.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bacterial deoxyribonucleoprotein (bDNP) structure and fragmentation mechanisms are not fully understood.
- Intracellular nucleases play a role in DNA processing and organization within bacterial cells.
Purpose of the Study:
- To investigate the in situ fragmentation of bDNP in various bacterial species using endogenous endonucleases.
- To characterize the resulting DNA fragments and associated proteins.
Main Methods:
- Spheroplasts of Escherichia coli, Serratia marcescens, Pseudomonas fluorescens, and Micrococcus luteus were treated with Ca2+ or Ca2+, Mg2+-dependent endonucleases.
- Extracted nuclease-split bDNP was analyzed using electrophoresis to determine fragment sizes and protein composition.
Main Results:
- Electrophoresis revealed high molecular weight (nuclease-resistant) and low molecular weight fragments (100-120 nucleotide pairs) of bDNP.
- Similar electrophoretic mobility of small DNA fragments across species indicated an orderly bDNP structure.
- Acid-soluble protein fractions in gram-negative bacteria showed similarities to calf thymus histones H2a and H2b.
Conclusions:
- Bacterial bDNP exhibits an orderly structure, with fragmentation yielding specific DNA fragment sizes.
- The presence of histone-like proteins suggests conserved structural roles in bacteria.
- Heterogeneity in nuclease sensitivity, membrane interaction, and protein distribution indicates differential functional states within the bacterial genome.