Primary structure of Serratia marcescens anthranilate synthase component II.

The amino acid sequence of anthranilate synthase component II (AS II) from Serratia marcescens was determined. The cysteine residue essential for glutamine utilization was alkylated selectively by iodo [1-14C]acetamide prior to separation of the two protein components of anthranilate synthase. The isolated AS II then was subjected to cleavage by cyanogen bromide and by trypsin after citraconylation to obtain overlapping fragments. AS II is a single polypeptide chain of 192 residues having a calculated molecular weight of 20,956. The active site region is virtually identical to that of the Pseudomonas putida AS II enzyme (Kawamura, M., Keim, P.S., Goto, Y., Zalkin, H., and Heinrikson, R.L. (1978) J. Biol. Chem. 253, 4659-4668). Overall amino acid sequence similarity is 43%.