Biomaterial Database

The 68 kDa DNA compacting nucleoid protein from soybean chloroplasts inhibits DNA synthesis in vitro. 1999

G C Cannon, and L N Ward, and C I Case, and S Heinhorst

Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg 39406-4043, USA.

Nucleoids were purified from chloroplasts of dividing soybean cells and their polypeptide composition analyzed by SDS-polyacrylamide gel electrophoresis. Of the 15-20 nucleoid-associated polypeptides, several demonstrated DNA binding activity. Upon disruption of the nucleoids with high concentrations of NaCl, a subset of these proteins and the majority of chloroplast DNA were recovered in the supernatant after centrifugation. Removal of the salt by dialysis resulted in formation of nucleoprotein complexes resembling genuine nucleoids. Purification of these structures revealed three major proteins of 68, 35 and 18 kDa. After purification of the 68 kDa protein to homogeneity, this protein was able to compact purified chloroplast DNA into a nucleoid-like structure in a protein concentration-dependent fashion. Addition of the 68 kDa protein to an in vitro chloroplast DNA replication system resulted in complete inhibition of nucleotide incorporation at concentrations above 300 ng of 68 kDa protein per microg of template DNA. These results led to in situ immunofluorescence studies of chloroplasts replicating DNA which suggested that newly synthesized DNA is not co-localized with nucleoids. Presumably, either the plastid replication machinery has means of removing nucleoid proteins prior to replication or the concentration of nucleoid proteins is tightly regulated and the proteins turned over in order to allow replication to proceed.

UI	MeSH Term	Description	Entries
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010940	Plant Proteins	Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which PLANT PROTEINS, DIETARY is available.	Plant Protein,Protein, Plant,Proteins, Plant
D011092	Polyethylene Glycols	Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.	Macrogols,Polyoxyethylenes,Carbowax,Macrogol,Polyethylene Glycol,Polyethylene Oxide,Polyethyleneoxide,Polyglycol,Glycol, Polyethylene,Glycols, Polyethylene,Oxide, Polyethylene,Oxides, Polyethylene,Polyethylene Oxides,Polyethyleneoxides,Polyglycols,Polyoxyethylene
D002458	Cell Fractionation	Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.	Cell Fractionations,Fractionation, Cell,Fractionations, Cell
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D002499	Centrifugation, Density Gradient	Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Centrifugations, Density Gradient,Density Gradient Centrifugation,Density Gradient Centrifugations,Gradient Centrifugation, Density,Gradient Centrifugations, Density
D002736	Chloroplasts	Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.	Chloroplast,Etioplasts,Etioplast
D003902	Detergents	Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.	Cleansing Agents,Detergent Pods,Laundry Detergent Pods,Laundry Pods,Syndet,Synthetic Detergent,Agent, Cleansing,Agents, Cleansing,Cleansing Agent,Detergent,Detergent Pod,Detergent Pod, Laundry,Detergent Pods, Laundry,Detergent, Synthetic,Detergents, Synthetic,Laundry Detergent Pod,Laundry Pod,Pod, Detergent,Pod, Laundry,Pod, Laundry Detergent,Pods, Detergent,Pods, Laundry,Pods, Laundry Detergent,Synthetic Detergents
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D013025	Glycine max	An annual legume. The SEEDS of this plant are edible and used to produce a variety of SOY FOODS.	Soy Beans,Soybeans,Bean, Soy,Beans, Soy,Soy Bean,Soybean