The ts- swoH-1 mutant of A. nidulans was swollen and lysed during vegetative growth at restrictive temperature. The swoH gene was mapped to chromosome II and cloned by complementation. The sequence showed that the swoH gene encodes a homologue of nucleoside diphosphate kinases (NDKs). Cell extract from the swoH-1mutant is low in NDK activity. Sequence of the mutant allele and structural modeling suggested that the swoH-1 mutation distorts the enzyme active site. The swoH gene fused with 3xHA tag at the N-terminus complemented swoH-1 mutant indicating the functional integrity of the fusion protein. The tagged protein possessed the phosphate transferase activity as analyzed by TLC. Similar to other eukaryotes, SwoHp in A. nidulans forms a hexamer based on results of western blot of a native gel and subunit interactions of the modeled protein structure. Although NDK has been considered a housekeeping enzyme in nucleotide metabolism, recent evidence suggests that it is also an important regulatory protein in many cellular processes. In mammals, NDKs are involved in differentiation and tumor metastasis. In plants, NDK interacts with the phytochrome molecules. Although null mutants of E. coli, S. cerevisiae and S. pombe are viable, deletion of the swoH gene was lethal in A. nidulans suggesting that NDK plays a more important role in this filamentous fungus.
Fungal Genet. Newsl. 50 (Supl):abstract
Full conference title:
22nd Fungal Genetics Conference
- Fungal Genetics Conference 22nd (2001)