The extreme thermostable pyrophosphatase from Sulfolobus acidocaldarius: enzymatic and comparative biophysical characterization.


Abstract

Recombinant pyrophosphatase from the hyperthermophilic archaebacterium Sulfolobus acidocaldarius (S-PPase) has been heterologously expressed in Escherichia coli and could be purified in large quantities. S-PPase, previously described as a tetrameric enzyme, was shown to be a homohexameric protein that had catalytic activity with Mg2+ > Zn2+ > Co2+ > Mn2+ > Ni2+, Ca2+. CD and FTIR spectra demonstrate a similar overall fold for S-PPase and PPases from E. coli (E-PPase) and Thermus thermophilus (T-PPase). The relative proportions of secondary structure elements in S-PPase are close to those of a previously proposed model. S-PPase is extremely heat resistant. Even at 95 degrees C the half-life of catalytic activity is 2.5 h, which is dramatically increased in the presence of divalent cations. More than one Mg2+ per monomer is needed for catalysis, but no more than one Mg2+ per monomer is sufficient for thermal stabilization. The Tm values for S-PPase are 89 degrees C (+EDTA), 99 degrees C (+Mg2+), and >100 degrees C (+Mn2+), compared to 58 degrees C (+EDTA), 84 degrees C (+Mg2+), and 93 degrees C (+Mn2+) for E-PPase and 86 degrees C (+EDTA), 99 degrees C (+Mg2+), and 96 degrees C (+Mn2+) for T-PPase. The guanidium hydrochloride-induced unfolding follows an unknown mechanism with a biphasic kinetic and an unstable intermediate. Unfolding curves of the S-, E-, and T-PPase are independent of the method applied (CD spectroscopy and fluorescence) and show a sigmoidal and monophasic transition, indicating a change in global structure during unfolding, which can be described by a two-state process comprising dissociation and denaturation of the folded hexamer into six monomers. The respective DeltaGN-->D(25 degrees C) values of the three PPases vary from 220 to 290 kJ/mol for the overall process and are not significantly higher for the two thermophilic PPases. The stabilizing effect of Mg2+ DeltaDeltaG(25 degrees C) is 16 kJ/mol for E-PPase and 5.5-8 kJ/mol for S-PPase and T-PPase. Study holds ProTherm entries: 12946, 12947, 12948, 12949, 12950, 12951, 12952, 12953, 12954, 12955, 12956, 12957, 12958, 12959, 12960, 12961, 12962, 12963, 12964, 12965 Extra Details: EDTA(5 mM) was added in the experiment pyrophosphatase; stability GdnHCl; denaturation; Mg2+; hexamer

Submission Details

ID: whvmgAkk3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:44 p.m.

Version: 1

Publication Details
Hansen T;Urbanke C;Leppänen VM;Goldman A;Brandenburg K;Schäfer G,Arch. Biochem. Biophys. (1999) The extreme thermostable pyrophosphatase from Sulfolobus acidocaldarius: enzymatic and comparative biophysical characterization. PMID:10049508
Additional Information

Number of data points 44
Proteins Inorganic pyrophosphatase ; Inorganic pyrophosphatase ; Inorganic pyrophosphatase ; Inorganic pyrophosphatase ; Inorganic pyrophosphatase ; Inorganic pyrophosphatase
Unique complexes 3
Assays/Quantities/Protocols Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG_H2O ; Experimental Assay: Cm temp:50.0 C, details:Additives EDTA (5 mM), ; Experimental Assay: m temp:50.0 C, details:Additives EDTA (5 mM), ; Experimental Assay: dG_H2O temp:50.0 C, details:Additives EDTA (5 mM), ; Experimental Assay: Cm temp:50.0 C ; Experimental Assay: m temp:50.0 C ; Experimental Assay: dG_H2O temp:50.0 C ; Experimental Assay: Cm details:Additives EDTA (5 mM), ; Experimental Assay: m details:Additives EDTA (5 mM), ; Experimental Assay: dG_H2O details:Additives EDTA (5 mM), ; Experimental Assay: Cm details:Additives EDTA (5 mM), ; Experimental Assay: m details:Additives EDTA (5 mM), ; Experimental Assay: dG_H2O details:Additives EDTA (5 mM), ; Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG_H2O ; Experimental Assay: Tm details:Additives Mn2+(5 mM), ; Experimental Assay: Tm details:Additives Mg2+(5 mM), ; Experimental Assay: Tm ionic:EDTA: 5 mM, details:Additives EDTA (5 mM), ; Experimental Assay: Tm details:Additives EDTA (5 mM),
Libraries Mutations for sequence SLLNVPAGKDLPEDIYVVIEIPANADPIKYEIDKESGALFVDRFMSTAMFYPCNYGYINHTLSLDGDPVDVLVPTPYPLQPGSVIRCRPVGVLKMTDEAGEDAKLVAVPHSKLSKEYDHIKDVNDLPELLKAQIAHFFEHYKDLEKGKWVKVEGWENAEAAKAEIVASFERAKNK ; Mutations for sequence ANLKSLPVGDKAPEVVHMVIEVPRGSGNKYEYDPDLGAIKLDRVLPGAQFYPGDYGFIPSTLAEDGDPLDGLVLSTYPLLPGVVVEVRVVGLLLMEDEKGGDAKVIGVVAEDQRLDHIQDIGDVPEGVKQEIQHFFETYKALEAKKGKWVKVTGWRDRKAALEEVRACIARYKG ; Mutations for sequence MKLSPGKNAPDVVNVLVEIPQGSNIKYEYDDEEGVIKVDRVLYTSMNYPFNYGFIPGTLEEDGDPLDVLVITNYQLYPGSVIEVRPIGILYMKDEEGEDAKIVAVPKDKTDPSFSNIKDINDLPQATKNKIVHFFEHYKELEPGKYVKISGWGSATEAKNRIQLAIKRVSGGQ
Sequence Assay Result Units