6.3.3.4	-	639035	
6.3.3.4	homologous to Class B asparagine synthases	639031	
6.3.3.4	Streptomyces venezuelae YJ028 is utilized as the heterologous host for the expression of four structural clavulanic acid biosynthesis genes, which encode carboxyethylarginine synthase (ceas2), beta-lactam synthetase (bls2), clavaminate synthase (cas2), and proclavaminate amidinohydrolase (pah2). The genes are cloned into pIBR25 expression vector containing ermE promoter to generate pBS4. The cas2 gene is also cloned into pSET152 to generate pCas2. It is then integrated into the genome of Streptomyces venezuelae YJ028	742159