Cloning and characterization of dihydrofolate reductase from a facultative alkaliphilic and halotolerant bacillus strain

TY - JOUR

T1 - Cloning and characterization of dihydrofolate reductase from a facultative alkaliphilic and halotolerant bacillus strain

AU - Redecke, Lars

AU - Brehm, Maria A

AU - Bredehorst, Reinhard

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Elucidation of the molecular basis of the stability of enzymes from extremophilic organisms is of fundamental importance for various industrial applications. Due to the wealth of structural data from various species, dihydrofolate reductase (DHFR, EC 1.5.1.3) provides an excellent model for systematic investigations. In this report, DHFR from alkaliphilic Bacillus halodurans C-125 was cloned and expressed in E. coli. Functional analyses revealed that BhDHFR exhibits the most alkali-stable phenotype of DHFRs characterized so far. Optimal enzyme activity was observed in a slightly basic pH region ranging from 7.25 to 8.75. Alkali-stability is associated with a remarkable resistance to elevated temperatures (half-life of 60 min at 52.5 degrees C) and to high concentrations of urea (up to 3 M). Although the secondary structure shows distinct similarities to those of mesophilic DHFR molecules, BhDHFR exhibits molecular features contributing to its alkaliphilic properties. Interestingly, the unique phenotype is diminished by C-terminal addition of a His-tag sequence. Therefore, His-tag-derivatized BhDHFR offers the opportunity to obtain deeper insights into the specific mechanisms of alkaliphilic adaption by comparison of the three dimensional structure of both BhDHFR molecules.

AB - Elucidation of the molecular basis of the stability of enzymes from extremophilic organisms is of fundamental importance for various industrial applications. Due to the wealth of structural data from various species, dihydrofolate reductase (DHFR, EC 1.5.1.3) provides an excellent model for systematic investigations. In this report, DHFR from alkaliphilic Bacillus halodurans C-125 was cloned and expressed in E. coli. Functional analyses revealed that BhDHFR exhibits the most alkali-stable phenotype of DHFRs characterized so far. Optimal enzyme activity was observed in a slightly basic pH region ranging from 7.25 to 8.75. Alkali-stability is associated with a remarkable resistance to elevated temperatures (half-life of 60 min at 52.5 degrees C) and to high concentrations of urea (up to 3 M). Although the secondary structure shows distinct similarities to those of mesophilic DHFR molecules, BhDHFR exhibits molecular features contributing to its alkaliphilic properties. Interestingly, the unique phenotype is diminished by C-terminal addition of a His-tag sequence. Therefore, His-tag-derivatized BhDHFR offers the opportunity to obtain deeper insights into the specific mechanisms of alkaliphilic adaption by comparison of the three dimensional structure of both BhDHFR molecules.

KW - Adaptation, Physiological

KW - Amino Acid Sequence

KW - Bacillus

KW - Bacterial Proteins

KW - Cloning, Molecular

KW - Conserved Sequence

KW - Enzyme Stability

KW - Hydrogen-Ion Concentration

KW - Kinetics

KW - Molecular Sequence Data

KW - Potassium Chloride

KW - Protein Structure, Secondary

KW - Recombinant Proteins

KW - Sequence Alignment

KW - Sequence Analysis, Protein

KW - Sodium Chloride

KW - Temperature

KW - Tetrahydrofolate Dehydrogenase

KW - Urea

U2 - 10.1007/s00792-006-0013-6

DO - 10.1007/s00792-006-0013-6

M3 - SCORING: Journal article

C2 - 17021659

VL - 11

SP - 75

EP - 83

JO - EXTREMOPHILES

JF - EXTREMOPHILES

SN - 1431-0651

IS - 1

ER -