Comparative Biochemical Characterization of Two GroEL Homologs from the Cyanobacterium<i>Synechococcus elongatus</i>PCC 7942

Huq, Saaimatul; Sueoka, Keigo; Narumi, Shoichi; Arisaka, Fumio; Nakamoto, Hitoshi

doi:10.1271/bbb.100493

Cited by 18 publications

(21 citation statements)

References 33 publications

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“…This pattern has been observed across almost all bacterial species that have two groEL genes, one as part of a bicistronic operon and the other as a monocistronic gene. GroEL-1 exhibits higher chaperone activity as well as ATPase activity than GroEL-2 (Cpn60), both in Synechococcus elongatus PCC7942 (Huq et al, 2010) and in Anabaena (A. A. Potnis et al, unpublished results).…”

Section: The Hsr In Cyanobacteriamentioning

confidence: 97%

Cyanobacterial heat-shock response: role and regulation of molecular chaperones

2014

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Cyanobacteria constitute a morphologically diverse group of oxygenic photoautotrophic microbes which range from unicellular to multicellular, and non-nitrogen-fixing to nitrogen-fixing types. Sustained long-term exposure to changing environmental conditions, during their three billion years of evolution, has presumably led to their adaptation to diverse ecological niches. The ability to maintain protein conformational homeostasis (folding-misfolding-refolding or aggregationdegradation) by molecular chaperones holds the key to the stress adaptability of cyanobacteria. Although cyanobacteria possess several genes encoding DnaK and DnaJ family proteins, these are not the most abundant heat-shock proteins (Hsps), as is the case in other bacteria. Instead, the Hsp60 family of proteins, comprising two phylogenetically conserved proteins, and small Hsps are more abundant during heat stress. The contribution of the Hsp100 (ClpB) family of proteins and of small Hsps in the unicellular cyanobacteria (Synechocystis and Synechococcus) as well as that of Hsp60 proteins in the filamentous cyanobacteria (Anabaena) to thermotolerance has been elucidated. The regulation of chaperone genes by several cis-elements and trans-acting factors has also been well documented. Recent studies have demonstrated novel transcriptional and translational (mRNA secondary structure) regulatory mechanisms in unicellular cyanobacteria. This article provides an insight into the heat-shock response: its organization, and ecophysiological regulation and role of molecular chaperones, in unicellular and filamentous nitrogen-fixing cyanobacterial strains.

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Section: The Hsr In Cyanobacteriamentioning

confidence: 97%

Cyanobacterial heat-shock response: role and regulation of molecular chaperones

2014

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“…The GroEL1 protein (native or recombinant) formed a tetradecamer, but the GroEL2 protein formed a heptamer or dimer. Moreover, both GroEL oligomers were very unstable (Huq et al, 2010). It is not known if the other cyanobacterial Cpn60 proteins have similar physicochemical characteristics.…”

Section: Chaperonin 60: An Evolutionarily Diverse Molecular Chapementioning

confidence: 99%

“…This finding is not confined to the mycobacteria as the Cpn60 protein of the gastric pathogen, Helicobacter pylori, is also a dimer or a tetramer when analysed in solution ). In addition, the cyanobacterium Synechoccus elongatus has two Cpn60 proteins with Cpn60.1 forming an unstable tetradecamer while Cpn60.2 forms a heptamer (Huq et al, 2010). It might be proposed that bacterial growth under unusual conditions could influence the oligomerisation state of Cpn60.…”

Section: Chaperonin 60: An Evolutionarily Diverse Molecular Chapementioning

confidence: 99%

Chaperonin 60: a paradoxical, evolutionarily conserved protein family with multiple moonlighting functions

2013

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Chaperonin 60 is the prototypic molecular chaperone, an essential protein in eukaryotes and prokaryotes, whose sequence conservation provides an excellent basis for phylogenetic analysis. Escherichia coli chaperonin 60 (GroEL), the prototype of this family of proteins, has an established oligomeric-structure-based folding mechanism and a defined population of folding partners. However, there is a growing number of examples of chaperonin 60 proteins whose crystal structures and oligomeric composition are at variance with GroEL, suggesting that additional complexities in the protein-folding function of this protein should be expected. In addition, many organisms have multiple chaperonin 60 proteins, some of which have lost their protein-folding ability. It is emerging that this highly conserved protein has evolved a bewildering variety of additional biological functions - known as moonlighting functions - both within the cell and in the extracellular milieu. Indeed, in some organisms, it is these moonlighting functions that have been left after the loss of the protein-folding activity. This highlights the major paradox in the biology of chaperonin 60. This article reviews the relationship between the folding and non-folding (moonlighting) activities of the chaperonin 60 family and discusses current knowledge on their molecular evolution focusing on protein domains involved in the non-folding chaperonin functions in an attempt to understand the emerging biology of this evolutionarily ancient protein family.

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“…These studies, as well as studies in Thermosynechococcus elongatus (Sato et al. 2008) and Synechococcus elongatus PCC 7942 (Huq et al. 2010), thus suggest that the monocistronic groEL paralog has undergone a subfunctionalization while the bicistronic groEL paralog maintains a housekeeping function.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Chaperonin Gene Duplication in Stigonematalean Cyanobacteria (Subsection V)

et al. 2017

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Chaperonins promote protein folding and are known to play a role in the maintenance of cellular stability under stress conditions. The group I bacterial chaperonin complex comprises GroEL, that forms a barrel-like oligomer, and GroES that forms the lid. In most eubacteria the GroES/GroEL chaperonin is encoded by a single-copy bicistronic operon, whereas in cyanobacteria up to three groES/groEL paralogs have been documented. Here we study the evolution and functional diversification of chaperonin paralogs in the heterocystous, multi-seriate filament forming cyanobacterium Chlorogloeopsis fritschii PCC 6912. The genome of C. fritschii encodes two groES/groEL operons (groESL1, groESL1.2) and a monocistronic groEL gene (groEL2). A phylogenetic reconstruction reveals that the groEL2 duplication is as ancient as cyanobacteria, whereas the groESL1.2 duplication occurred at the ancestor of heterocystous cyanobacteria. A comparison of the groEL paralogs transcription levels under different growth conditions shows that they have adapted distinct transcriptional regulation. Our results reveal that groEL1 and groEL1.2 are upregulated during diazotrophic conditions and the localization of their promoter activity points towards a role in heterocyst differentiation. Furthermore, protein–protein interaction assays suggest that paralogs encoded in the two operons assemble into hybrid complexes. The monocistronic encoded GroEL2 is not forming oligomers nor does it interact with the co-chaperonins. Interaction between GroES1.2 and GroEL1.2 could not be documented, suggesting that the groESL1.2 operon does not encode a functional chaperonin complex. Functional complementation experiments in Escherichia coli show that only GroES1/GroEL1 and GroES1/GroEL1.2 can substitute the native operon. In summary, the evolutionary consequences of chaperonin duplication in cyanobacteria include the retention of groESL1 as a housekeeping gene, subfunctionalization of groESL1.2 and neofunctionalization of the monocistronic groEL2 paralog.

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Comparative Biochemical Characterization of Two GroEL Homologs from the CyanobacteriumSynechococcus elongatusPCC 7942

Cited by 18 publications

References 33 publications

Cyanobacterial heat-shock response: role and regulation of molecular chaperones

Cyanobacterial heat-shock response: role and regulation of molecular chaperones

Chaperonin 60: a paradoxical, evolutionarily conserved protein family with multiple moonlighting functions

Evolution of Chaperonin Gene Duplication in Stigonematalean Cyanobacteria (Subsection V)

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