“TCP-1/cpn60 chaperonin family”的意思、由来-开放百科全书

TCP-1/cpn60 chaperonin family is a family of evolutionarily related proteins.

This family includes members from the HSP60 chaperone family and the TCP-1 (T-complex protein) family.

The assembly of proteins has been thought to be the sole result of properties inherent in the primary sequence of polypeptides themselves. In some cases, however, structural information from other protein molecules is required for correct folding and subsequent assembly into oligomers.^[2] These 'helper' molecules are referred to as molecular chaperones, a subfamily of which are the chaperonins,^[3] which include 10 kDa and 60 kDa proteins. These are found in abundance in prokaryotes, chloroplasts and mitochondria. They are required for normal cell growth (as demonstrated by the fact that no temperature sensitive mutants for the chaperonin genes can be found in the temperature range 20 to 43 degrees Celsius^[2]) and are stress-induced, acting to stabilise or protect disassembled polypeptides under heat-shock conditions.^[3]

The 10 kDa chaperonin (cpn10 - or groES in bacteria) exists as a ring-shaped oligomer of between 6 and 8 identical subunits, whereas the 60 kDa chaperonin (cpn60 - or groEL in bacteria) forms a structure comprising 2 stacked rings, each ring containing 7 identical subunits.^[2] These ring structures assemble by self-stimulation in the presence of Mg²⁺-ATP. The cpn10 and cpn60 oligomers also require Mg²⁺-ATP in order to interact to form a functional complex, although the mechanism of this interaction is as yet unknown.^[4] This chaperonin complex is essential for the correct folding and assembly of polypeptides into oligomeric structures, of which the chaperonins themselves are not a part.^[3] The binding of cpn10 to cpn60 inhibits the weak ATPase activity of cpn60.

The 60 kDa form of chaperonin is the immunodominant antigen of patients with Legionnaire's disease,^[5] and is thought to play a role in the protection of the Legionella bacteria from oxygen radicals within macrophages. This hypothesis is based on the finding that the cpn60 gene is upregulated in response to hydrogen peroxide, a source of oxygen radicals. Cpn60 has also been found to display strong antigenicity in many bacterial species^[6] and has the potential for inducing immune protection against unrelated bacterial infections. The RuBisCO subunit binding protein (which has been implicated in the assembly of RuBisCO) and cpn60 have been found to be evolutionary homologues, the RuBisCO subunit binding protein having the C-terminal Gly-Gly-Met repeat found in all bacterial cpn60 sequences. Although the precise function of this repeat is unknown, it is thought to be important as it is also found in 70 kDa heat-shock proteins.^[5] The crystal structure of Escherichia coli GroEL has been resolved to 2.8 Å.^[7] The TCP-1 family of proteins act as molecular chaperones for tubulin, actin and probably some other proteins. They are weakly, but significantly, related to the cpn60/groEL chaperonin family.

Examples

References

1. ^{{cite journal |vauthors=Braig K, Otwinowski Z, Hegde R, etal |title=The crystal structure of the bacterial chaperonin GroEL at 2.8 A |journal=Nature |volume=371 |issue=6498 |pages=578–86 |date=October 1994 |pmid=7935790 |doi=10.1038/371578a0 |url=}}
2. ^¹²{{cite journal |doi=10.1038/333330a0 |vauthors=Hemmingsen SM, Woolford C, van der Vies SM, Tilly K, Dennis DT, Georgopoulos CP, Hendrix RW, Ellis RJ |title=Homologous plant and bacterial proteins chaperone oligomeric protein assembly |journal=Nature |volume=333 |issue=6171 |pages=330–334 |year=1988 |pmid=2897629}}
3. ^¹²{{cite journal |doi=10.1007/BF00019202 |vauthors=Prasad TK, Stewart CR |title=cDNA clones encoding Arabidopsis thaliana and Zea mays mitochondrial chaperonin HSP60 and gene expression during seed germination and heat shock |journal=Plant Mol. Biol. |volume=18 |issue=5 |pages=873–885 |year=1992 |pmid=1349837}}
4. ^{{cite journal |vauthors=Schmidt A, Schiesswohl M, Volker U, Hecker M, Schumann W |title=Cloning, sequencing, mapping, and transcriptional analysis of the groESL operon from Bacillus subtilis |journal=J. Bacteriol. |volume=174 |issue=12 |pages=3993–3999 |year=1992 |pmid=1350777 |pmc=206108}}
5. ^¹{{cite journal |vauthors=Hindersson P, Hoiby N, Bangsborg J |title=Sequence analysis of the Legionella micdadei groELS operon |journal=FEMS Microbiol. Lett. |volume=61 |issue=1 |pages=31–38 |year=1991 |pmid=1672279| doi = 10.1111/j.1574-6968.1991.tb04317.x }}
6. ^{{cite journal |vauthors=Gor D, Mayfield JE |title=Cloning and nucleotide sequence of the Brucella abortus groE operon |journal=Biochim. Biophys. Acta |volume=1130 |issue=1 |pages=120–122 |year=1992 |pmid=1347461 |doi=10.1016/0167-4781(92)90476-g}}
7. ^{{cite journal |doi=10.1038/371578a0 |vauthors=Joachimiak A, Horwich AL, Otwinowski Z, Sigler PB, Braig K, Hegde R, Boisvert DC |title=The crystal structure of the bacterial chaperonin GroEL at 2.8 Å |journal=Nature |volume=371 |issue=6498 |pages=578–586 |year=1994 |pmid=7935790}}