title: GroEL from the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC 125: molecular characterization and gene cloning.
abstract: The heat shock response of the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC 125 (PhTAC 125) gives rise to the production of several inducible proteins. Among these, the protein corresponding to a 55-kDa band on SDS-PAGE was purified to homogeneity and identified as a GroEL-like protein. The gene coding for this protein (PhGroEL) was cloned and sequenced; the deduced amino acid sequence shows 82% sequence identity to GroEL from Escherichia coli (EcGroEL). The ORF found in the 5' upstream region codes for a homologue of the GroES from E. coli (PhGroES, 71% sequence identity to EcGroES). PhGroEL shows a chaperone activity and can use GroES from E. coli as a co-chaperone. PhGroEL melting temperature, 6 degrees C lower than that of EcGroEL, and equilibrium unfolding experiments in urea showed a less stable protein architecture for the psychrophilic GroEL. The data herein reported demonstrate that PhGroEL cold adaptation consists in a shift of the protein properties toward lower temperatures without increasing catalytic efficiency at low temperatures. Primary extension analysis depicted a complex organization of regulative elements for the operon containing the genes coding for PhgroES and PhgroEL (PhgroE), suggesting that a fine-tuning of transcription can also be involved in thermal adaptation of PhTAC 125.
authors.affiliation: Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cynthia 4, 80126 Naples, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tosco
authors.forename: Leila
authors.initials: L
authors.lastname: Birolo
authors.forename: Stefania
authors.initials: S
authors.lastname: Madonna
authors.forename: Graziano
authors.initials: G
authors.lastname: Lolli
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sannia
authors.forename: Gennaro
authors.initials: G
authors.lastname: Marino
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D018835:Chaperonin 10 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018834:Chaperonin 60 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D011489:Protein Denaturation; D031161:Pseudoalteromonas / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; D004269:DNA, Bacterial; D000251:Adenosine Triphosphatases