Structural genes encoding the thermophilic alpha-amylases of Bacillus stearothermophilus and Bacillus licheniformis.

The genes encoding the thermostable alpha-amylases of Bacillus stearothermophilus and B. licheniformis were cloned in Escherichia coli, and their DNA sequences were determined. The coding and deduced polypeptide sequences are 59 and 62% homologous to each other, respectively. The B. stearothermophilus protein differs most significantly from that of B. licheniformis in that it possesses a 32-residue COOH-terminal tail. Transformation of E. coli with vectors containing either gene resulted in the synthesis and secretion of active enzymes similar to those produced by the parental organisms. A plasmid was constructed in which the promoter and the NH2-terminal two-thirds of the B. stearothermophilus coding sequence was fused out of frame to the entire mature coding sequence of the B. licheniformis gene. Approximately 1 in 5,000 colonies transformed with this plasmid was found to secrete an active amylase. Hybridization analysis of plasmids isolated from these amylase-positive colonies indicated that the parental coding sequences had recombined by homologous recombination. DNA sequence analysis of selected hybrid genes revealed symmetrical, nonrandom distribution of loci at which the crossovers had resolved. Several purified hybrid alpha-amylases were characterized and found to differ with respect to thermostability and specific activity

Regulation of purine metabolism connects KCTD13 to a metabolic disorder with autistic features

Genetic variation of the 16p11.2 deletion locus containing the KCTD13 gene and of CUL3 is linked with autism. This genetic connection suggested that substrates of a CUL3-KCTD13 ubiquitin ligase may be involved in disease pathogenesis. Comparison of Kctd13 mutant (Kctd13(-/-)) and wild-type neuronal ubiquitylomes identified adenylosuccinate synthetase (ADSS), an enzyme that catalyzes the first step in adenosine monophosphate (AMP) synthesis, as a KCTD13 ligase substrate. In Kctd13(-/-) neurons, there were increased levels of succinyl-adenosine (S-Ado), a metabolite downstream of ADSS. Notably, S-Ado levels are elevated in adenylosuccinate lyase deficiency, a metabolic disorder with autism and epilepsy phenotypes. The increased S-Ado levels in Kctd13(-/-)neurons were decreased by treatment with an ADSS inhibitor. Lastly, functional analysis of human KCTD13 variants suggests that KCTD13 variationmay alter ubiquitination of ADSS. These data suggest that succinyl-AMP metabolites accumulate in Kctd13(-/-) neurons, and this observation may have implications for our understanding of 16p11.2 deletion syndrome.ISSN:2589-004