Dihydrofolate reductase of the extremely halophilic archaebacterium Halobacterium volcanii. The enzyme and its coding gene.

T. Zusman, I. Rosenshine, G. Boehm, R. Jaenicke, B. Leskiw, M. Mevarech

Research output: Contribution to journalArticlepeer-review

Abstract

Halobacterium volcanii mutants that are resistant to the dihydrofolate reductase inhibitor trimethoprim contain DNA sequence amplifications. This paper describes the cloning and nucleic acid sequencing of the amplified DNA sequence of the H. volcanii mutant WR215. This sequence contains an open reading frame that codes for an amino acid sequence that is homologous to the amino acid sequences of dihydrofolate reductases from different sources. As a result of the gene amplification, the trimethoprim-resistant mutant overproduces dihydrofolate reductase. This enzyme was purified to homogeneity using ammonium sulfate-mediated chromatographies. It is shown that the enzyme comprises 5% of the cell protein. The amino acid sequence of the first 15 amino acids of the enzyme fits the coding sequence of the gene. Preliminary biochemical characterization shows that the enzyme is unstable at salt concentrations lower than 2 M and that its activity increases with increase in the KCl or NaCl concentrations.

Original languageEnglish
Pages (from-to)18878-18883
Number of pages6
JournalThe Journal of biological chemistry
Volume264
Issue number32
StatePublished - 15 Nov 1989

Fingerprint

Dive into the research topics of 'Dihydrofolate reductase of the extremely halophilic archaebacterium Halobacterium volcanii. The enzyme and its coding gene.'. Together they form a unique fingerprint.

Cite this