title: GroEL of the nitrogen-fixing cyanobacterium Anabaena sp. strain L-31 exhibits GroES and ATP-independent refolding activity.
abstract: The nitrogen-fixing cyanobacterium, Anabaena L-31 has two Hsp60 proteins, 59 kDa GroEL coded by the second gene of groESL operon and 61 kDa Cpn60 coded by cpn60 gene. Anabaena GroEL formed stable higher oligomer (>12-mer) in the presence of K(+) and prevented thermal aggregation of malate dehydrogenase (MDH). Using three protein substrates (MDH, All1541 and green fluorescent protein), it was found that the refolding activity of Anabaena GroEL was lower than that of Escherichia coli GroEL, but independent of both GroES and ATP. This correlated with in vivo data. GroEL exhibited ATPase activity which was enhanced in the presence of GroES and absence of a denatured protein, contrary to that observed for bacterial GroEL. However, a significant role for ATP could not be ascertained during in vitro folding assays. The monomeric Cpn60 exhibited much lower refolding activity than GroEL, unaffected by GroES and ATP. In vitro studies revealed inhibition of the refolding activity of Anabaena GroEL by Cpn60, which could be due to their different oligomeric status. The role of GroES and ATP may have been added during the course of evolution from the ancient cyanobacteria to modern day bacteria enhancing the refolding ability and ensuring wider scope of substrates for GroEL.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
authors.forename: Akhilesh A
authors.initials: AA
authors.lastname: Potnis
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India hemaraj@barc.gov.in.
authors.forename: Hema
authors.initials: H
authors.lastname: Rajaram
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
authors.forename: Shree K
authors.initials: SK
authors.lastname: Apte
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D017033:Anabaena / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018835:Chaperonin 10 / Q000737:chemistry / Q000378:metabolism*; D018834:Chaperonin 60 / Q000737:chemistry / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000737:chemistry; D009876:Operon; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D055503:Protein Multimerization; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D000255:Adenosine Triphosphate; D008291:Malate Dehydrogenase
keywords: Anabaena; Cpn60; GroEL; GroES; chaperone