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The chaperonins, GroEL and GroES, are present ubiquitously and provide a paradigm in the understanding of assisted protein
folding. Due to its essentiality of function, GroEL exhibits high sequence conservation across species. Complete genome sequencing
has shown the occurrence of duplicate or multiple copies of groEL genes in bacteria such as Mycobacterium tuberculosis and Corynebacterium glutamicum. Monophyly of each bacterial clade in the phylogenetic tree generated for the GroEL protein suggests a lineage-specific duplication.
The duplicated groEL gene in Actinobacteria is not accompanied by the operonic groES despite the presence of upstream regulatory elements. Our analysis suggests that in these bacteria the duplicated groEL genes have undergone rapid evolution and divergence to function in a GroES-independent manner. Evaluation of multiple sequence
alignment demonstrates that the duplicated genes have acquired mutations at functionally significant positions including those
involved in substrate binding, ATP binding, and GroES binding and those involved in inter-ring and intra-ring interactions.
We propose that the duplicate groEL genes in different bacterial clades have evolved independently to meet specific requirements of each clade. We also propose
that the groEL gene, although essential and conserved, accumulates nonconservative substitutions to exhibit structural and functional variations.
Electronic Supplementary Material Electronic Supplementary material is available for this article at
and accessible for authorised users.
[Reviewing Editor: Dr. Debashish Bhattacharya] 相似文献
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Chang LJ Chen WH Minion FC Shiuan D 《Biochemical and biophysical research communications》2008,367(1):213-218
Mycoplasmas in general are rarely exposed to severe environmental changes except during its colonization and infection processes. Genomic analysis indicates that Mycoplasma hyopneumoniae possesses the genes of a single sigma factor and the HrcA repressor of negative regulation of the heat-shock response. A perfect inverted repeat sequence (5′-CTGGCACTT-N9-AAGTGCCAA-3′) upstream of the DnaK gene has also been identified. In the present study, we demonstrate the functionality of HrcA-CIRCE interactions using the gel electrophoretic mobility shift assay. The presence of the unique sigma factor, HrcA repressor, and the CIRCE-like sequences reveals that mycoplasmal species may all use the negative regulatory mechanism in the heat-shock response. It is conceivable that mycoplasmas may have evolved a single HrcA repressor-based mechanism which might be the most simple and economical way of controlling HSP gene expression. 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(5):1176-1180
The groESL operon of the halophilic lactic acid bacterium Tetragenococcus halophila was cloned by a PCR-based method. The molecular masses of GroES and GroEL proteins were calculated to be 10,153 and 56,893 Da, respectively. The amount of groESL mRNA was increased 3.8-fold by heat shock (45°C), and 4-fold by high NaCl (3-4 M). The Bacillus subtilis σA-like constitutive promoter existed in front of groES, and was used under both normal and stress (heat shock and high salinity) conditions. 相似文献
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