Cold-shock domain
Encyclopedia
Im molecular biology, the cold-shock domain (CSD) is a protein domain
of about 70 amino acid
s which has been found in prokaryotic
and eukaryotic DNA
-binding proteins
. Part of this domain is highly similar to the RNP-1 RNA
-binding motif.
When Escherichia coli
is exposed to a temperature drop from 37 to 10 degrees Celsius, a 4-5 hour lag phase occurs, after which growth
is resumed at a reduced rate
. During the lag phase, the expression of around 13 proteins, which contain cold shock domains is increased 2-10 fold. These so-called 'cold shock' protein
s are thought to help the cell to survive in temperatures lower than optimum growth temperature, by contrast with heat shock
proteins, which help the cell
to survive in temperatures greater than the optimum, possibly by condensation of the chromosome
and organisation of the prokaryotic nucleoid
.
Protein domain
A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...
of about 70 amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s which has been found in prokaryotic
Prokaryote
The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...
and eukaryotic DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
-binding proteins
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
. Part of this domain is highly similar to the RNP-1 RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
-binding motif.
When Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
is exposed to a temperature drop from 37 to 10 degrees Celsius, a 4-5 hour lag phase occurs, after which growth
Cell growth
The term cell growth is used in the contexts of cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"...
is resumed at a reduced rate
Rate
In mathematics, a rate is a ratio between two measurements, often with different units. If the unit or quantity in respect of which something is changing is not specified, usually the rate is per unit time. However, a rate of change can be specified per unit time, or per unit of length or mass or...
. During the lag phase, the expression of around 13 proteins, which contain cold shock domains is increased 2-10 fold. These so-called 'cold shock' protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s are thought to help the cell to survive in temperatures lower than optimum growth temperature, by contrast with heat shock
Heat shock
In biochemistry, heat shock is the effect of subjecting a cell to a higher temperature than that of the ideal body temperature of the organism from which the cell line was derived.-Heat shock response:...
proteins, which help the cell
Cell
-Science and technology:*Cell , the functional basic unit of life*Cell , a term used in an electronic circuit design schematics*Cell , a three-dimensional element, part of a higher-dimensional object*Cell , a scientific journal...
to survive in temperatures greater than the optimum, possibly by condensation of the chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
and organisation of the prokaryotic nucleoid
Nucleoid
The nucleoid is an irregularly-shaped region within the cell of a prokaryote that contains all or most of the genetic material. In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane. The genome of prokaryotic organisms generally is a circular, double-stranded...
.