Cloning and characterisation of the hint homologue of the thermophile thermus thermophilus

Screening of a genomic library of the thermophile Thermus thermophilus revealed a novel thermophilic hint gene, homologues of which are highly conserved in genera from archaea to mammals. Hint belongs to the HIT protein super-family, which contains two broad groups, Fhit, associated with tumour suppression in eukaryotes and Hint with putatitive protein kinase C inhibitory activity. In T. thermophilus the 321bp gene has a GC content of 67% overall and 94.4% in the third nucleotide position, with unusually no thymine as a wobble base. The gene product, a small highly conserved 11996Da predicted soluble cytoplasmic protein, offers an ideal opportunity to investigate thermostabilising amino acid substitutions. Here we report on the characterisation of the novel hint sequence.