DK5653/DK1622 Vegetative

Isovaleryl-CoA (IV-CoA) is usually derived from the degradation of leucine using the Bkd (branched-chain ketoacid dehydrogenase) complex. In myxobacteria we have previously identified an alternative pathway for IV-CoA formation that branches from the well-known mevalonate dependent isoprenoid biosynthesis pathway and we could already identify the 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (MvaS) to be involved in this pathway in Myxococcus xanthus which is induced under leucine limiting conditions like in mutants impaired in leucine degradation or during myxobacterial fruiting body formation. Here we show that proteins involved in leucine degradation are also involved in the alternative IV-CoA biosynthesis by catalyzing the reverse reactions of that used in leucine degradation. Moreover, we conducted a global gene expression experiment comparing vegetative cells of wild type and a bkd mutant. Thus we could identify a five-gene operon which was highly upregulated in a bkd mutant and that contains the mvaS gene and other genes which might be involved in a mevalonate-shunt pathway leading from mevalonate to 3-methylglutaconyl-CoA. Additionally, several genes involved in outer membrane biosynthesis and a plethora of genes encoding regulatory proteins are decreased explaining the complex phenotype of a bkd mutant that includes a lack of adhesion in developmental submers culture. Keywords: Vegetative growth mutant vs. wild-type comparison 6 independent biological replicates. Normalized ratios to Cy3.